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MANUAL  OF  ANATOMY 

SYSTEMATIC  AND  PRACTICAL,  INCLUDING 
EMBRYOLOGY 


MANUAL  OF  ANATOMY 


SYSTEMATIC  AND  PRACTICAL,  INCLAJDING 
EMBRYOLOGY 


BY 


A.  M.  BUCHANAN,  M.A.,  M.D.,  CM,  LR.F.P.S.  Glas. 

PROFESSOR   OF   ANATOMY   IN  ANDERSON'S  COLLEGE,   GLASGOW;   EXAMINER   IN  ANATOMY   FOR 
THE    TRIPLE    QUALIFICATION    OF  THE    SCOTTISH    LICENSING    BODIES  :  EXAMINER    IN  AN- 
ATOMY  FOR  THE  DENTAL    DIPLOMA.   AND    EXAMINER   IN    ANATOMY    (HUMAN   AND 
COMPARATIVE)     FOR    THE    FELLOWSHIP,   OF  THE    ROYAL    FACULTY  OF  PHY- 
SICIANS AND  SURGEONS  OF  GLASGOW:   EX-EXAMINER   IN  ANATOMY  TO 
THE     UNIVERSITY     OF     GLASGOW  ;     FORMERLY    SENIOR     DEMON- 
STRATOR OF  ANATOMY  IN  THE  UNIVERSITY    OF  GLASGOW. 


SECOND  EDITION 


VOL.  I. 


nrr/f  -ji-.n  ili.i  siu.\ri<)\s.  mostly  oitmiswh  a.\i>  i\  <uir<>i,-s 


St.  Louis 

C.  V.  MosBY  Company 

1914 


/ 


CD 
CD 

etc 


DEDICATED  BY  PERMISSION 

TO 

THE  RIGHT   HONOURABLE  LORD   LISTER, 

O.M.,  LL.D.,  D.C.L.,  F.R.S.,  Etc., 

IN    GRATEFUL    ACKNOWLEDGMENT    OF    THE 

POWERFUL    INFLUENCE    WHICH    HE    EXERCISED    OVER    THE 

INTELLECTUAL    CULTURE    OF    HIS    GLASGOW    STUDENTS,    OF    WHOM 

THE    AUTHOR   WAS   ONE. 


I 

^ 
^ 


PREFACE  TO  SECOND  IMPRESSION 

The  First  Edition  of  this  Manual  has  been  so  favourably  received, 
and  was  published  such  a  short  time  ago,  that  it  has  seemed  un- 
necessarv  to  make  any  verv  important  alterations,  or  to  effect  a 
thorough  and  complete  revisal  in  the  meantime,  in  view  of  the  early 
call  for  a  Second  Edition.  In  reprinting  this  Second  Impression  it 
has  been  considered  advisable  not  to  allow  the  Manual  to  remain 
out  of  print  (as  a  revised  edition  throughout  would  necessitate),  it 
being  the  only  text-book  of  its  kind  which  adheres  to  the  old 
anatomical  nomenclature. 

The  feeling  among  many  teachers  of  anatomy  seems  to  be  setting 
against  the  adoption  of  the  Basle  nomenclature  in  its  entirety. 
Moreover,  among  students  there  is  a  great  deal  of  dissatisfaction  at 
its  use  on  account  of  its  being  so  cumbrous,  and  occasionally  not 
quite  accurate.  It  has  therefore  been  considered  advisable  to  retain 
the  old  nomenclature,  which  is  so  simple  and  so  correct  for  all 
practical  purposes,  until  such  time  as  a  standard  nomenclature 
has  been  fixed  and  generally  accepted.  The  Appendix  containing  a 
large  number  of  the  terms  of  the  Basle  nomenclature  has,  however, 
been  retained  for  the  use  of  those  who  may  desire  to  refer  to  it. 

The  errata  and  omissions,  noted  in  the  First  Edition,  have  been 
put  right,  and  certain  critical  remarks  have  received  willing 
attention. 

The  subject  of  the  ossification  of  bones,  now  so  much  modified, 
has  been  made  more  in  conformity  with  the  views  of  recent 
investigators,  and  in  certain  cases  will  be  doubtless  more  acceptable 
to  students  than  previous  accounts. 

Anderson's  College,  Glasgow, 
May,   1914. 


PREFACE    TO    FIRST    EDITION 

In  the  preparation  of  this  work  the  object  of  the  author  has  been 
to  combine  a  manual  of  practical  anatomy  with  a  text-book  of 
systematic  anatomy,  and  so  furnish  students  with  a  complete 
treatise  on  the  subject,  written  entirely  by  himself. 

The  section  on  osteology  is  treated  of  in  an  exhaustive  manner, 
and  an  account  of  the  ossification  of  each  bone  follows  its  description. 

The  joints  are  described  in  the  order  in  which  they  are  met  with 
in  the  course  of  dissection.  Each  of  the  sections  of  the  upper  limb, 
lower  limb,  abdomen,  thorax,  and  head  and  neck  has  appended  to 
it  a  complete  guide  to  its  dissection,  giving  full  information  as  to 
the  manner  in  which  the  dissections  should  be  carried  out,  and 
detailing  the  structures  which  should  be  exposed. 

The  minute  anatomy  of  the  viscera  and  organs  is  fully  described, 
and  illustrated  by  drawings  from  microscopical  preparations  in  the 
possession  of  the  author. 

vSpecial  sections  are  devoted  to  the  nervous  system,  the  eye,  the 
ear,  and  the  nose,  and  these  are  also  fully  illustrated. 

The  subject  of  embryology  is  dealt  with  by  appending  to  the 
description  of  each  viscus  and  organ  a  concise  account  of  its  develop- 
ment, in  the  hope  that  this  method  may  enhst  the  attention  of 
students  in  this  very  important  subject. 

The  work  is  amply  illustrated  by  drawings  which  have  been 
executed  by  the  well-known  anatomical  artist,  Mr.  James  T. 
Murray,  of  Edinburgh,  who  has  done  his  work  with  the  greatest 
care  and  excellence,  and  whom  the  author  desires  to  thank  cordially. 
Most  of  the  drawings  are  coloured  (many  of  them  in  three  tints), 
and  the  drawings  of  the  bones  have  the  origins  and  insertions  of  the 
muscles  delineated  in  different  colours,  the  origins  being  in  red  and 
the  insertions  in  blue.  The  majority  of  the  drawings  have  been 
specially  executed  for  this  work,  and  the  sources  from  which  the 
others  have  been  taken  are  duly  acknowledged.     The  author  begs 


PREFACE  ix 

to  thank  all  who  have  generously  and  kindly  granted  permission  to 
use  their  drawings. 

Throughout  the  whole  of  the  work  the  author,  from  his  long  ex- 
perience, not  only  as  a  teacher  but  also  as  an  examiner  on  various 
Boards,  has  kept  constantly  in  view  the  examinational  requirements 
of  students,  for  whom  this  work  is  specially  intended. 

He  has  to  acknowledge  with  deep  gratitude  the  valuable  assist- 
ance which  he  has  received  from  Dr.  J.  Archibald  Campbell,  Senior 
Demonstrator  of  Anatomy  in  Anderson's  College,  and  from  Mr. 
Hugh  F.  Watson,  Junior  Demonstrator.  He  has  also  gratefully  to 
thank  the  publishers  for  the  immense  amount  of  labour  which  they 
have  kindly  undertaken  in  various  directions,  for  the  very  great 
care  which  they  have  bestow^ed  upon  the  publication  of  this  work, 
and  for  their  uniform  courtesy.  Finally,  he  has  gratefully  to  thank 
Mr.  Alexander  Duncan,  B.A.,  LL.D.,  Librarian  to  the  Faculty  of 
Physicians  and  Surgeons  of  Glasgow,  for  many  acts  of  kind  and 
much  appreciated  aid. 

Anderson's  College,  Glasgow, 
May,  1906. 


ERRATA 

Page     40,  line  29,  for  vertical  read  vertebral. 
,,       112,    ,,    22,  for  mesaticocephalic  read  mesaticephalic. 
,,      134,    ,,    3,  for  zygomatic  read  external. 
,,      875,    ,,    14  from  bottom,  for  thyroid  read  thymus. 
,,      918,    ,,    4  from  bottom, /or  vestibuli  yeai^  terminalis. 
„    1033,    ,,    3  and  4  from  bottom,  transpose  "prevertebral  "  and 

"  pretracheal." 
.."    1303.    .,    26,  for  cinerea  read  terminalis. 
,,    1318,    ,,    2  from  bottom, /or  cinerea  j-eflc^  terminalis. 
,,    1325,    ,,    18  and  20, /or  cinerea  rea(f  terminalis. 


C  O  N  T  E  N  T  S 

PAGE 

Osteology         -------  1 

Arthrology       -------  260 

Upper  Limb                  ---...  ^^(^ 

Guide  to  dissection  of  the  upper  limb       -              -              -  386 

Lower  Limb    -------  399 

Guide  to  dissection  of  the  lower  limb       -              -              -  556 


A   MANUAL  OF   ANATOMY 


OSTEOLOGY 

The  skeleton  is  the  hard  '  dry  '  osseous  and  cartilaginous  frame- 
work of  the  body.     It  consists  in  the  adult  of  200  bones,  exclusive 
of  the  small  bones  of  the  ear  and  sesamoid  bones,  most  of  which 
are  held  together  by  ligaments.     The  functions  of  the  bones  are 
as  follows  :  (i)  they  impart  shape  to  the  body  ;  (2)  they  support 
the  soft  parts  ;  (3)  they  protect  important  organs  ;  and  (4)  they  ' 
afford  attachment  to   the  muscles.     In  the  performance  of  this 
latter  function  the  bones  are  to  be  regarded  as  passive  organs  of 
locomotion,  the  active  organs  being  the  muscles — that  is  to  say, 
the  bones  act  as  levers  to  the  muscles.     There  are  two  varieties 
of  skeleton,  namely,  endoskeleton  and  exoskeleton.     In  the  former, 
as  in  man,  the  bones  are  covered  by  soft  parts.     In  the  latter, 
as  in  Crustacea,  the  bones  are  so  disposed  as  to  lie  upon  the  surface, 
where  they  form  a  case  which  contains  the  soft  parts  of  the  animal. 
The  human  skeleton  is  arranged  in  two  divisions,  axial  and  appen- 
dicular.    The  axial  skeleton  comprises  the  head  and  trunk,  and 
the  appendicular   represents    the   limbs.     The   head   is   composed 
of  23  bones,   including  the  hyoid  bone.     The  trunk  is  made  up 
of   the   vertebral  column,  containing  26  separate  bones  in  adult 
life ;    the    sternum  ;    and   the   ribs,    with    their   costal    cartilages, 
24  in  number,  thus  making  51  bones  in  all  in  the  trunk.      The 
appendicular  skeleton  comprises  the  two  upper  or  pectoral  limbs, 
each  containing  32  bones,  exclusive  of  sesamoid  bones,  and  the 
two  lower  or  pelvic  limbs,  each  containing  31  bones,  also  exclusive 
of  sesamoid  bones. 

Descriptive  Terms. 

Apophysis  ('  grow  from  ')  :  this  is  any  process  or  swelling  on  a 
bone. 

iJiaphysis  ('grow  between  ')  :  this  term  is  applicable  to  long 
bones.  It  is  the  shaft  of  the  bone,  or  the  part  which  grows 
between  the  epiphyses. 

Epiphysis  {'  grow  upon  ')  :  this  is  a  process  of  bone  which  has 

I 


2  A   MANUAL  OF  ANATOMY 

a  secondary  centre  of  ossification,  and  which  is  attached  for  a 
time  to  the  principal  part  of  the  bone  by  cartilage,  but  subse- 
quently becomes  consolidated. 

Spine  :  this  is  a  sharp-pointed  process,  and  in  certain  bones 
is  erroneously  applied. 

Tubercle  ('  swelling  ')  :  a  small  rounded  prominence  on  a  bone. 

Tuberosity  :  an  exaggerated  tubercle. 

Trochanter  ('  running  round  '  or  '  rolled  ')  :  a  prominence  which 
has  a  rolled  or  wheel-like  arrangement,  and  which  runs  round  a 
portion  of  a  bone. 

Head :  a  rounded  eminence,  covered  by  cartilage,  at  the  extremity 
of  a  bone. 

Capitellum  :  a  small  head. 

Neck  :  a  constricted  portion  supporting  a  head. 

Condyle  ('knuckle'):  a  small  round  eminence  covered  by 
cartilage — in  reality  a  capitellum. 

Foramen  :  an  opening  in  the  sense  of  a  hole. 

Hiatus  :  an  opening  in  the  sense  of  a  gap. 

Meatus  (pi.  meatus)  :  a  passage  or  canal. 

Fissure  :  a  cleft  or  slit. 

Fossa  :  a  shallow  depression. 

Groove  :  a  furrow  or  gutter. 

Facet  (Fr.  facette,  '  a  little  face  ')  :  a  small  plane  articular  surface; 

Sinus  or  antrttm  :  a  cavity  in  the  interior  of  a  bone. 

Glenoid  :  like  a  shallow  socket. 

Cotyloid  :  cup-like. 

Malleolus  :  a  small  hammer. 

Neural :  pertaining  to  the  nervous  system. 

Medullary  :  pertaining  to  the  medulla  or  marrow. 

Clinoid  :  like  a  bed. 

Trochlea  :  a  pulley. 

Styloid  :  pen-like. 

Ventral :  pertaining  to  the  belly  aspect  of  the  body. 

Dorsal :  pertaining  to  the  back  aspect.  In  man  ventral  and  dorsal 
are  synonymous  with  anterior  and  posterior  in  the^erect  posture. 

Cephalic  :  towards  the  head. 

Caudal :  towards  the  tail. 

Ankylosis  :  bony  union  between  two  bones  which  are  normally 
separate. 

Mesial  plane  :  this  is  the  imaginary  longitudinal  plane  which 
divides  the  body  into  two  very  nearly  symmetrical  halves,  right 
and  left.  It  extends  from  the  mesial  line  on  the  ventral  aspect 
to  the  mesial  line  on  the  dorsal  aspect. 

Sagittal :  this  means  pertaining  to  the  antero-posterior  mesial 
plane  with  which  it  is  parallel,  and  it  practically  means  dorso- 
ventral  or  antero-posterior. 

Coronal :  this  means  intersecting  the  antero-posterior  mesial 
plane  at  right  angles  in  a  vertical  direction,  and  it  is  practically 
synonymous  with  transverse. 


OSTEOLOGY  3 

Internal  or  mesial :  near  to  the  mesial  plane  ;  and  external  or 
lateral :  farther  away  from  the  mesial  plane. 

Preaxial  and  postaxial :  these  terms  were  originally  used  in 
connection  with  the  embryo.  Preaxial,  proximal,  or  cephalic 
means  towards  the  head  (superior),  and  postaxial,  distal,  or 
caudal  means  towards  the  tail  (inferior). 

Morphology.— This  is  the  science  which  investigates  the  form 
and  structure  of  parts  and  organs  in  reference  to  the  series  of 
changes  through  which  thej'  pass  during  their  development.  In  a 
morphological  sense  parts  of  man's  body  may  be  compared  with 
one  another,  or  parts  of  the  body  of  one  animal  may  be  compared 
with  apparently  similar  parts  in  the  body  of  another  animal,  and 
in  this  way  their  actual  identity  may  be  established. 

Homology. — Parts  or  organs  which  are  represented  in  different 
animals  are  said  to  be  homologous  (homogenetic)  when  they  are 
constructed  on  the  same  type  and  have  the  same  embryonic  origin, 
although  they  may  differ  in  function.  For  example,  the  upper 
limb  of  man  and  the  fore-limb  of  a  quadruped  are  homologous  (homo- 
genetic). Parts  in  the  body  of  man  are  said  to  be  serially  homologous 
(homodynamic)  when  they  are  repeated.  For  example,  the  humerus 
is  serially  homologous  with  the  femur. 

Analogy. — This  is  identity  in  function,  but  not  necessarily  in 
structure.  The  gills  of  a  fish  are  analogous  with  the  lungs  of 
man,  though  differing  in  structure. 

Segmental  Type. — This  consists  in  the  repetition  longitudinally 
of  a  series  of  segments  similar  to  each  other — e.g.,  vertebrae,  and 
ribs. 

Chemical  Composition  of  Bone. — Osseous  tissue  belongs  to  the 
connective  tissues,  and  it  consists  of  an  organic  matrix  or 
ground  substance,  impregnated  with  mineral  matter.  The  mineral 
matter  is  composed  chiefly  of  calcium  salts,  and  so  it  petrifies  the 
ground  substance.  The  organic  matrix  is  usually  spoken  of  as 
the  animal  matter,  and  it  forms  about  33  per  cent,  of  the  entire 
bone.  The  mineral  matter  is  spoken  of  as  the  earthy  matter,  and 
it  forms  about  67  per  cent,  of  the  bone. 

The  animal  matter  imparts  toughness  and  elasticity  to  the  bone, 
and  is  composed  of  very  delicate  fibres,  which  are  collected  into 
bundles,  held  together  by  cement  substance.  The  fibres  consist  of 
collagen,  which  is  converted  into  gelatin  by  boiling.  The  animal 
matter  can  be  separated  from  the  earthy  matter  by  steeping  a 
bone  for  some  time  in  dilute  hydrochloric  acid,  the  effect  of  the 
acid  being  to  dissolve  out  the  earthy  matter.  When  bone  is  so 
treated  it  is  said  to  be  decalcified.  There  is  left  a  tough,  flexible, 
elastic  substance,  which  can  be  bent  and  twisted  in  various  direc- 
tions, and  even  tied  into  a  knot,  but  no  amount  of  force  applied 
to  it,  or  pressure  laid  upon  it,  would  cause  it  to  break.  A  bone 
when  so  treated  retains  its  original  shape,  but  it  loses  weight  to 
the  extent  of  about  two-thirds,  and  it  also  loses  its  property  of 
hardness,  so  that  it  is  incapable  of  beating  weight. 

I — 2 


4  A   MANUAL  OF  ANATOMY 

The  earthy  matter  imparts  hardness  and  rigidity  to  the  bone, 
and  is  composed  principally  of  calcium  salts,  of  which  the  most 
abundant  is  calcium  phosphate,  there  being  about  57  per  cent, 
of  this  salt  present.  Besides  this  there  are  calcium  carbonate 
in  the  proportion  of  about  7  per  cent.,  and  calcium  fluoride  in 
the  proportion  of  about  i  per  cent.  In  addition  to  the  calcium 
salts  there  are  about  i  per  cent,  of  magnesium  phosphate,  and 
about  I  per  cent,  of  sodium  chloride.  The  earthy  matter  may 
be  separated  from  the  animal  matter  by  burning  a  bone.  The 
first  effect   of    the    heat  is  to  char  the  animal  matter,  which  is 


Fig.  I. 


-Longitudinal  Section  through  the  Upper  End  of  the  Femur, 
SHOWING  Compact  and  Cancellated  Osseous  Tissues. 


subsequently  consumed.  When  so  treated  a  bone  is  said  to 
be  calcined,  and  the  process  is  spoken  of  as  combustion  or 
calcination.  There  is  left  a  white,  chalk-like,  very  brittle  substance, 
which,  if  of  small  size  and  carefully  handled,  retains  its  original 
shape.  The  slightest  rough  handling,  however,  will  cause  it  to 
break,  or  crumble  into  a  coarse  powder.  Calcined  bone  undergoes 
no  change  in  shape,  but  it  loses  weight  to  the  extent  of  about 
one-third.  It  also  loses  its  toughness  and  elasticity.  The  only 
property  it  now  possesses  is  hardness.  As  stated,  it  is  also  very 
brittle,  and,  by  reason  of  this,  it  cannot  be  bent  nor  twisted  in 


OSTEOLOGY  -5 

the  slightest  degree.  The  animal  and  earthy  matter,  as  they 
form  bone,  are  intimately  combined. 

The  proportion  of  about  one-third  of  animal  matter  to  about 
two- thirds  of  earthy  matter  applies  to  the  healthy  adult.  In 
young  children  the  relative  amount  of  animal  matter  is  much 
greater,  so  that  in  them  the  bones  are  very  tough  and  elastic, 
but  not  very  hard,  and  therefore  not  capable  of  bearing  much 
weight.  In  old  age  there  is  a  relatively  large  amount  of  earthy 
matter  present.  The  bones  of  old  persons,  therefore,  are  very 
hard  and  brittle,  but  not  very  tough  and  elastic  ;  hence  the  frequency 
of  fractures  in  old  persons  from  slight  causes. 

Structure  of  Bone. — There  are  two  varieties  of  osseous  tissue, 
namely,  compact,  and  spongy  or  cancelated.  Compact  osseous 
tissue  is  so  named  because  its  constituents  are  so  closely  packed 
together  that   the  bone  appears   to  the   naked  eye  {macroscopic) 


Fig.  2. — Structure  of  Compact  Bone. 

A,    Longitudinal    section,    showing    Haversian    canals;    B,   Transverse 
section,  showing  Haversian  systems. 

to  be  dense  and  close  like  ivory.  Spongy  or  cancellated  osseous 
tissue,  on  the  other  hand,  presents  an  open  porous  appearance  like 
a  sponge.  It  is  called  cancellated  because  it  resembles  lattice- 
work. These  two  varieties  of  osseous  tissue  merge  very  gradually 
into  one  another. 

When  compact  bone  is  viewed  under  the  microscope  in  thin 
transverse  section  it  presents  a  number  of  small  round  or  oval 
openings,  and  when  viewed  in  thin  vertical  section  it  presents 
short  longitudinal  tubes,  called  Haversian  canals.  These  pervade 
every  part  of  compact  bone,  and  the  innermost  open  into  the 
marrow  canal  of  long  bones,  whilst  the  outermost  open  by  minute 
orifices  on  the  external  surface.  They  range  in  diameter  from  ^oVx)' 
to  vj^jj  inch,  the  average  being  ^,00  inch.  The  smallest  lie  nearest 
the  external  surface,  and  the  largest  are  nearest  the  marrow  canal. 
They  are  very  short  and  longitudinal  in  direction,  and  they  com- 


A  MANUAL  OF  ANATOMY 


municate  freel}^  with  one  another  by  connecting  canals,  some  of 
which  are  obUque  and  others  transverse.  These  connecting  canals 
are  very  small,  having  a  diameter  of  only  o-qVo  inch.  The  Haversian 
canals  thus  form  a  freely  intercommunicating  system  of  tubes 
throughout  compact  bone.  The  largest  canals  contain  each  an 
arteriole,  a  radicle  vein,  one  or  two  lymphatics,  and  a  small 
amount  of  marrow  tissue.  The  smallest  canals  contain  only 
one  bloodvessel,  which  is  of  the  nature  of  a  capillary.  Those 
nearest  the  external  surface  also  contain  very  delicate  thread-like 
processes  of  the  periosteum.  Nerve  fibrils  have  been  demonstrated 
in  bone  by  Kolliker,  Remy,  and  Variot. 

The  bone  around  the  Haversian  canals  is  arranged  in  the  form 
of  concentric  plates,  called  Haversian  or  concentric  bone  lamellce. 
In  transverse  section  these  appear  as  concentric  rings,  and  in  longi- 


Lacuna,  with  Bone  Cell  and 
Canaliculi 


Marrow  Tissue 


Large  Haversian  Canal  [ 

Venous  Radicle 


'  Lymphatic  Vessel 

Arteriole 
Nerve  Fibrils 


Fig.  3. — Diagram  of  a  Haversian  System,  minus  the  Concentric 
Bone  Lamella. 

tudinal  section  as  parallel  lines.  In  the  interspaces  between  the 
systems  of  Haversian  or  concentric  lamellae  there  are  intermediate, 
interstitial,  or  ground  lamellcB,  and  near  the  external  surface  there 
are  circumferential  or  peripheral  lamellcz,  which  are  parallel  with  the 
surface.  Some  of  the  canals  which  pierce  the  circumferential  lamellae 
are  devoid  of  concentric  lamellae,  and  are  known  as  Volkmann's 
canals.  In  the  interspaces  between  the  Haversian  or  concentric 
lamellae  there  are  small  fusiform  cavities,  known  as  the  hone 
lacuncB.  These  are  about  o  oVo  inch  in  length,  and,  like  the  lamellae, 
they  are  arranged  concentrically  round  the  Haversian  canals. 
Radiating  from  these  lacunae  there  are  minute  channels,  called  hone 
canaliculi,  which  pass  through  perforations  in  the  lamellae,  and  so 
serve  to  connect  the  various  lacunae  with  one  another.  Some  of 
those  radiating  from  the  innermost  ring  of  lacunae  communicate 


OSTEOLOGY  7 

directl\'  with  the  Haversian  canal.  The  canahculi  thus  constitute  a 
system  of  intercommunicating  cliannels  whicli  maintain  a  con- 
nection directly  and  indirectly  between  a  given  Haversian  canal 
and  the  lacunae  arranged  concentrically  around  it,  and  traverse 
the  lamellae  in  their  course.  Each  lacuna  contains  a  protoplasmic 
nucleated  cell,  called  the  hon^  cell,  which  almost  completely 
hlls  it,  and  sends  off  processes  into  the  canaliculi  communicating 
with  it.  The  canaliculi  contain  nutritive  fluid  derived  from  the 
arteriole.  A  given  Haversian  canal,  with  its  concentric  bone 
lamellae,  concentric  bone  lacunae,  and  canaliculi,  constitutes  a 
Haversian  system,  and  compact  bone  is  simply  an  aggregation  of 
such  systems,  with,  in  addition,  the  intermediate  and  circumfer- 
ential lamellae.  Certain  lamellae  are  perforated  perpendicularly  by 
fibres  which  thus  bind  them  together.  These  fibres  are  known 
as  the  pirf orating  fibre:^  of  Sharpey.  Some  of  them  are  composed 
of  white  fibrous  tissue,  and  others  of  elastic  tissue,  and  those 
nearest  the  periphery  are  connected  with  the  periosteum  from 
which  they  are  derived.  Others,  however,  more  deeply  placed, 
have  no  apparent  direct  connection  with  the  periosteum.  The 
perforating  fibres  are  absent  from  the  lamellae  of  the  Haversian 
systems. 

Cancellated  bone  is  composed  of  very  slender  trabeculae,  which 
are  arranged  in  a  reticular  manner  so  as  to  enclose  spaces,  known 
as  the  msdidlary  spaces.  These  spaces,  in  the  recent  state,  are 
filled  with  marrow.  The  trabeculae  consist  of  superimposed 
lamellae  of  compact  bone.  The  strongest  lamellae  are  disposed  in 
the  direction  in  which  the  greatest  pressure  has  to  be  borne,  and 
these  are  known  as  pressure  lamellce.  Other  lamellae  which  intersect 
these,  are  spoken  of  as  tension  lamellce.  The  use  of  cancellated 
bone  is  to  impart  sufficient  strength  without  adding  unduly  to 
weight. 

Classification  of  Bones. — Bones  are  arranged  in  four  classes,  as 
follows:  Long;  short;  tabular;  and  irregular. 

A  long  bone  consists  of  a  shaft  and  two  articular  extremities. 
The  shaft  is  more  or  less  cylindrical,  and  contains  a  marrow  canal, 
which  is  surrounded  principally  by  compact  bone.  The  articular 
extremities  are  composed  of  cancellated  tissue,  except  at  the  sur- 
face where  there  is  a  thin  shell  of  compact  bone.  Long  bones  are 
found  in  the  appendicular  skeleton. 

A  short  bone  consists  mainly  of  cancellated  tissue,  except  at  the 
surface  where  there  is  a  thin  covering  of  compact  bone.  Short 
bones  are  more  or  less  oblong  in  shape,  and  are  found  in  the  carpus 
and  tarsus. 

A  tabular  bone  is  composed  of  two  plates  or  tables  of  compact 
bone,  which  enclose  between  them  cancellated  tissue.  The  scapula, 
ilium,  and  tegmental  bones  of  the  skull  belong  to  this  class.  In 
the  case  of  the  latter  the  cancellated  tissue  is  called  diploe. 

An  irregular  bone  is  one  which  is  so  irregular  in  form  and  in  the 
relative  distriljution  of  the  compact  and  cancellated  tissues  as  to  be 


8  A   MANUAL  OF  ANATOMY 

excluded  from  any  of  the  preceding  classes.  The  vertebrae  belong 
to  this  class. 

Ossification.- — All  bones  are  originally  membranous.  Some  of 
them— for  example,  the  tegmental  bones  of  the  cranium  and  most 
of  the  bones  of  the  face — ossifj'  in  membrane,  but  the  majority 
pass  through  a  cartilaginous  stage  before  becoming  ossified.  There 
are,  therefore,  two  modes  of  ossification,  namely  intramembranous 
and  intracartilaginous,  and  bones  are  consequently  spoken  of  as 
membrane-  and  car  til  age-bones. 

Centres  of  Ossification. — These  are  primary  and  secondary.  The 
primary  centre,  which  as  a  rule  appears  earl}^  in  intra-uterine  life, 


Fig. 


-Ossification  in  Membrane. 


is  that  from  which  the  ossification  of  the  principal  part  of  the  bone 
proceeds.  This,  in  the  case  of  a  long  bone,  is  the  shaft  or  diaphysis. 
The  secondary  centres,  which  for  the  most  part  do  not  appear  until 
after  birth,  are  those  from  which  the  ossification  of  outgrowths  of  a 
bone  proceeds,  these  forming  what  are  known  as  the  epiphyses. 

Ossification  in  Membrane. — In  this  mode  of  ossification  the  bone  is  preceded 
by  fibrous  tissue.  The  fibres  of  this  tissue  are  known  as  osteogenetic  fibres, 
and  they  are  arranged  in  small  bundles.  The  tissue  is  verj''  vascular,  and 
contains  many  nucleated  cells,  called  osteoblasts.  At  the  centre  of  ossification 
the  osteogenetic  fibres,  which  have  a  covering  of  osteoblasts,  become  calcified, 
and  bony  spicula  are  thus  formed,  which  radiate  towards  the  circumference 
of  the  bone.     These  radiating  spicula  are  connected  at  frequent  intervals,  and 


OSTEOLOGY 


so  build  up  a  bony  reticulum.  As  the  osteogenetic  fibres  grow  and  shoot 
out.  they  earn,-  with  them  coatings  of  osteoblasts,  and  the  process  of  cal- 
careous incrustation  goes  on.  so  that  the  bony  spicula  increase  in  length, 
and  gradually  approach  the  j>eriphery.  During  this  process  of  spicular  bony 
formation  many  of  the  osteoblasts  are  left  behind,  and  become  imprisone«l 
in  the  lacunar  spaces  of  the  forming  bone,  where  they  represent  the  future 
bone  cells.  The  ossification  of  a  membrane  bone  is  thus  effected  by  means 
of  osteogenetic  fibres  plus  osteoblasts,  the  fibres  acting  as  outrunners  and 
becoming  calcified. 

Ossification  in  Cartilage. — The  cartilage  is  covered  by  a  membrane,  called 
the  pciic/undnuni.  whuch  corresponds  to  the  periosteum,  and  the  process  of 
ossification  takes  place  in  three  stages. 

First  Stage. — In  this  stage  the  ossification  is  partly  cndocliondral,  and  partly 
e:t:ch::ndral  or  on  the  surface  beneath  the  perichondrium.  In  the  endo- 
chondral form  the  cartilage  ceUs  at  the  centre  become 
enlarged,  and  the  inter\'ening  matrix  becomes  cal- 
cified. Above  and  below  the  centre  the  cartilage 
cells  are  arranged  in  long  columns,  directed  towards 
each  extremity.  The  matrix  between  these  columns 
becomes  calcified  by  an  extension  of  the  calcareous 
matter  at  the  centre,  which  now  surrounds  the  cell- 
columns.  The  spaces  in  the  calcified  matrix,  which 
contain  these  columns,  are  known  as  the  primary 
areyliF.  .\t  the  same  time,  ectochondral  cr  subperi- 
ehondral  ossification  is  proceeding  in  a  manner 
similar  to  what  takes  place  in  membranous  ossifica- 
tion, that  is  to  say.  b\'  osteogenetic  fibres,  osteo- 
blasts, and  calcareous  impregnation.  In  this  way 
s-;veral  laj'ers  cf  bone  are  laid  down  at  the  surface 
beneath  the  perichondrium,  and  these  constitute  the 
circumferential  lamella-.  During  this  process  some 
of  the  osteoblasts  are  detained  in  lacunar  spaces,  and 
form  the  boui'  cells. 

Second  Stage. — This  is  knoA\-n  as  the  stage  of  irrup- 
tion. The  inner  or  osteogenetic  layer  of  the  peri- 
chondrium bursts  in  through  openings  in  the  cir- 
cumferential lamelbe,  in  the  form  of  osteogenetic 
fibres,  osteoblasts,  and  osteoclasts  or  bone  destroyers. 
These  incursions  reach  the  calcified  matrix,  and  the 
osteoclasts  now  commence  their  destructive  work. 
The  cartilage  cells  of  the  primar\'  areolae,  as  well  as 
the  walls  of  these  areote,  are  absorbed,  and  larger 
spaces,  callefl  secondary  areolce.  are  formed  in  the 
original  calcified  matrix.  These  spaces  contain  osteo- 
genetic fibres  and  osteoblasts,  and  the  latter  now 
build  up  lamella:  of  bone. 

Third  Stage. — This  is  a  repetition  of  the  preceding 
two  stages.  The  cartilage  cells  arrange  them- 
selves  in    ro\vs  ;    the   intervening   matrix   becomes 

calcified,  and  invests  them;  the  enclosed  cartilage  cells  atrophy  and  give 
rise  to  primary  areola; ;  the  osteoclasts  produce  partial  absorption  of  the 
calcified  cartilage,  giving  rise  to  medullary  spaces;  and  the  osteogenetic 
fibres  and  osteoblasts  build  up  lamelUe  of  bone.  Simultaneously  with  these 
processes,  subperiosteal  ossification  is  going  on.  The  medullary  canal  is 
due  to  absorption  by  the  osteoclasts  of  the  osseous  tissue  in  the  centre  of  the 
shaft. 

The  ossification  of  the  epiphyses  of  a  bone  is  endochondral. 

Periosteum. — The  periosteum  is  a  fibrous,  vascular  membrane, 
wliicli  closely  invests  bones,  except  where  there  is  articular  cartilage, 


Fig.  5. — Ossification 
IN  Cartilage. 


lo  A   MANUAL  OF  ANATOMY 

at  the  margin  of  which  it  ceases.  It  consists  of  two  layers- — outer 
and  inner.  The  fibres  of  the  outer  layer  are  arranged  closely,  and 
it  is  therefore  dense.  The  inner  layer  consists  chiefly  of  ramifying 
elastic  fibres.  Between  the  inner  layer  and  the  surface  of  the 
shaft  of  a  long  bone  there  is,  especially  during  the  development 
and  growth  of  the  bone,  a  layer  of  subperiosteal  areolar  tissue. 
Within  its  meshes  cells,  called  osteoblasts,  accumulate  during  the 
period  of  growth.  These  cells  emerge  from  the  outermost  Haversian 
canals  along  the  course  of  the  entering  arteries,  and  they  represent 
the  hone  cells  of  the  bone-lacunse  of  compact  bone  which  have 
migrated  outwards.  The  osteoblasts  take  an  important  part  in 
the  formation  of  bone  during  its  growth. 

The  periosteum  is  richly  supplied  with  arteries  which,  after  ramif}^- 
ing,  enter  the  outermost  Haversian  canals,  along  with  fine  processes 
of  the  inner  periosteal  layer.  The  periosteum  serves  (i)  as  a  bed 
in  which  the  arteries  subdivide  before  entering  the  bone,  and  (2) 
to  give  a  firm  hold  to  tendons  and  ligaments.  It  also  takes  part 
in  ossification  and  regeneration  of  bone.  When  the  periosteum  is 
stripped  from  a  bone  the  uncovered  portion  is  liable  to  necrosis 
and  exfoliation. 

Marrow  or  Medulla. — The  marrow  fills  the  marrow  canals  of  long 
bones  and  the  medullary  spaces  of  cancellated  bone,  and  it  also 
sends  processes  into  the  innermost  Haversian  canals.  It  is  composed 
of  a  reticular  fibrous  matrix,  which  is  pervaded  by  many  blood- 
vessels and  cells,  the  latter  being  called  myelocytes  (marrow  cells). 
There  are  two  kinds  of  marrow,  yellow  and"  red,  which  differ  as  to 
the  character  of  the  cells.  In  yellow  marrow  most  of  the  cells  have 
become  transformed  into  fat  cells,  so  that  the  marrow  resembles 
adipose  tissue.  Red  marrow  contains  very  few  fat  cells.  Many  of 
its  cells  are  colourless,  protoplasmic,  nucleated  cells,  which  resemble 
the  leucocytes  of  the  blood,  though  of  larger  size,  and  like  them  are 
capable  of  amoeboid  movement.  Other  reddish  cells,  called  ery- 
throblasts,  are  present,  which  are  the  sources  from  which  large 
numbers  of  red  blood  corpuscles  are  formed.  In  addition  to  these 
two  sets  of  cells,  there  are  large  multinucleated,  protoplasmic  cells, 
called  the  myeloplaxes  of  Robin,  which  play  an  important  part  in 
the  absorption  of  bone. 

Yellow  marrow  is  found  in  the  marrow  canals  of  long 
bones,  whilst  red  marrow  occurs  in  (i)  articular  ends  of  long 
bones  ;  (2)  medullary  spaces  of  cancellated  bone  ;  (3)  bodies  of 
the  vertebrae;  (4)  sternum;  (5)  ribs;  and  (6)  the  diploe  of  the  cranial 
bones.  Marrow  serves  the  following  uses:  (i)  it  (red  marrow)  is 
an  important  blood-forming  organ  (red  corpuscles);  (2)  it  contributes 
to  the  nourishment  of  bone;  and  (3)  it  serves  as  a  light  packing 
material  for  all  hollow  spaces  within  bones,  with  the  exception  of 
the  air-sinuses  in  the  bones  of  the  head. 

The  wall  of  the  marrow  canal  of  all  long  bones  and  that 
of  the  medullary  spaces  of  all  cancellated  bone  are  lined  with 
a  very  delicate  layer  of  areolar  tissue,  which  is  richly  provided 


THE  BONES  OF  THE  TRUNK  ii 

with  bloodvessels.     This  is  known  as  the  endosteum  or  medullary 
membrane. 

Osseous  tissue  is  richly  supplied  with  bloodvessels,  which  are 
derived  from  the  periosteum  and  marrow. 

I.    THE   BONES    OF   THE    TRUNK. 

A.  The  Vertebral  Column. 

The  vertebral  column  is  composed  of  thirty-three  vertebrae  in  the 
young  subject,  and  these  in  the  adult  are  divided  into  two  classes, 
namely,  true  or  movable,  and  false,  immovable,  or  fixed.  The 
true  vertebrae  are  those  which,  though  connected  by  ligaments, 
are  quite  distinct  from  each  other,  so  that  a  limited  amount  of 
movement  is  allowed  between  them.     The  false  vertebrae  are  those 


Superior  Articular 
Process 


Fig.  6. — The  Sixth  Thoracic  Vektebra  (Superior  View). 

which,  though  distinct  up  to  a  certain  ])eriod  of  life,  subsequently 
become  ankylosed.  The  true  vertebra;  are  subdivided  into  three 
groups — cervical,  thoracic,  and  lumbar.  The  false  vertebrae  are 
subdivided  into  two  groups — sacral,  and  coccygeal. 

Component  Parts  of  a  Complete  Vertebra. — A  complete  vertebra 
is  composed  of  a  body  or  centrum  ;  a  neural  arch,  consisting  of 
two  pedicles  and  two  laminae  (neurapopkyses)  ;  a  spinous  pro- 
cess, or  neural  spine  ;  two  transverse  processes ;  four  articular 
processes  [zy ^apophyses),  two  superior  and  two  inferior  ;  and  a 
spinal  or  neural  foramen.  The  body  forms  the  anterior  or  ventral 
part  of  the  bone,  and  is  somewhat  disc-shai)ed.  The  neural 
arch  consists  of  two  halves,  the  anterior  jK)rtion  of  each  being 
the  pedicle,  and  the  ])Osterior  portion  the  lamina.     The  jjedicles 


12  A  MANUAL  OF  ANATOMY 

present,  above  and  below,  the  superior  and  inferior  vertebral  notches. 
The  spinous  process  is  formed  by  the  fusion  of  the  two  laminae  in 
the  median  line  posteriorly.  The  transverse  processes  project  out- 
wards, one  at  either  side,  from  the  neural  arch  at  the  junction  of 
the  pedicle  and  lamina.  The  articular  processes,  two  superior  and 
two  inferior,  project  upwards  and  downwards  from  the  junction  of 
the  pedicle  and  lamina  at  either  side,  and  they  are  covered  by 
cartilage.  The  spinal  or  neural  foramen  is  enclosed  by  the  body 
and  neural  arch.  It  is  bounded  in  front  by  the  posterior  surface 
of  the  body,  on  either  side  by  a  pedicle  and  lamina,  and  behind  by 
the  fusion  of  the  laminae  to  form  the  spinous  process. 

Structure  of  a  Vertebra. — The  body  is  composed  of  cancellated 
tissue,  covered  by  a  thin  layer  of  compact  bone.  The  chief  lamellae 
are  disposed  in  almost  vertical  curves,  the  convexities  of  which  are 
directed  towards  the  periphery.  Crossing  these  there  are  horizontal 
lamellae,  which  are  nearly  parallel  with  the  superior  and  inferior 
surfaces.  The  cancellated  tissue  is  permeated  by  venous  channels 
which  converge  to  the  two  large  foramina  on  the  posterior  surface 
of  the  body.  The  neural  arch  and  its  processes  are  chiefly  com- 
posed of  compact  bone,  the  amount  of  cancellated  tissue  being  for 
the  most  part  small. 

The  Cervical  Vertebrae. 

The  cervical  vertebrae  are  seven  in  number,  and  they  occupy 
the  region  of  the  cervix  or  neck.  The  distinctive  character  of  all 
cervical  vertebrae  is  the  presence  of  an  aperture  at  either  side  of 
the  body,  called  the  costo-transverse  foramen.  The  first  or  atlas, 
the  second  or  axis,  and  the  seventh  or  vertebra  prominens  have 
such  pronounced  characters  that  they  require  a  special  description. 

A  Typical  Cervical  Vertebra. — The  body  is  small  and  elongated 
from  side  to  side.  The  superior  surface  presents  at  either  side  an 
antero-posterior  lip,  the  inner  surface  of  which  is  sloped  towards  the 
superior  surface,  and  embraces  the  corresponding  bevelled  lateral 
border  of  the  inferior  surface  of  the  body  above.  The  whole 
surface  is  thus  concave  from  side  to  side,  and  the  posterior  lip  is 
on  a  slightly  higher  level  than  the  anterior.  The  inferior  surface 
is  bevelled  laterally,  and  its  anterior  lip  is  on  a  lower  level  than 
the  posterior.  The  inferior  surface  is  convex  from  side  to  side, 
and  concave  from  before  backwards.  The  superior  and  inferior 
surfaces  give  attachment  to  the  intervertebral  discs.  The  anterior 
surface  is  convex  from  side  to  side,  and  concave  from  above  down- 
wards. It  is  covered  by  the  anterior  common  ligament,  and  it 
presents  a  number  of  nutrient  foramina.  The  posterior  surface  is 
flat,  and  presents  several  nutrient  foramina,  two  of  which,  one  at 
either  side  of  the  middle  line,  are  large,  for  the  escape  of  the  venae 
basis  vertebrae.  The  posterior  surface  is  related  to  the  posterior 
common  hgament.  Each  lateral  surface  forms  the  inner  boundary 
of  the  costo-transverse  foramen. 
.    The  pedicles  spring  at  either  side  from  the  posterior  part  of  the 


THE  BONES  OF  THE   TRUNK 


13 


lateral  surface  of  the  body,  where  each  encroaches  rather  nearer 
the  upper  than  the  lower  surface.  They  are  smooth  and  almost 
cylindrical,  and  their  direction  is  outwards  and  backwards.  Above 
and  below  each  pedicle  there  is  a  well-marked  vertebral  notch,  the 
superior  being  narrower  and  slightly  shallower  than  the  inferior. 
The  superior  notch  lodges  a  spinal  nerve.  When  two  vertebrae  are 
in  position  the  contiguous  vertebral  notches,  at  either  side,  form 
an  intervertebral  foramen. 

The  laminae  spring  each  from  a  pedicle.     They  are  compressed 


Costo-transverse  Foramen 


Anterior  Tubercle 


Costo-transverse 
Lamella 


Body 


Back  of  Inferior  / 

Articular  Process         I 


Costal  Process 

Transverse  Process 


_  Pedicle 


Superior  Articular 
Lamina  Process 


Superior  Notch 


Inferior  Nutch 


Inferior  Articular  Process 


Fig.  7. — The  Fifth  Cervical  Vertebra. 
A,  Superior  view ;  B,  Lateral  view. 

from  before  backwards,  and  their  direction  is  backwards  and 
inwards  to  the  middle  line,  where  they  fuse,  and  so  give  rise  to  the 
sjjinous  process.  The  upper  border  and  adjacent  portion  of  the 
posterior  surface  of  each  lamina  give  attachment  to  the  liga- 
mentum  subflavum  connecting  it  to  the  lamina  above,  whilst  the 
lower  part  of  the  anterior  surface  near  the  lower  border  gives 
attachment  to  the  ligamentum  subflavum  connecting  it  to  the 
lamina  below. 
The  spinous  process  is  forinerl  by  the  fusion  of  the  two  laminae. 


£4  A  MANUAL  OF  ANATOMY 

It  is  triangular,  and  its  direction  is  backwards  and  slightly  down- 
wards. Superiorly  it  presents  an  antero-posterior  ridge  for  an 
interspinous  ligament,  and  interiorly  a  grooved  surface,  also  for 
an  interspinous  ligament.  It  terminates  behind  in  a  bifid  extremity, 
which,  in  the  case  of  the  third,  fourth,  and  fifth  vertebrge,  pre- 
sents a  distinct  triangular  notch.  The  bifurcated  extremity  gives 
attachment  to  the  deep  fibres  of  the  ligamentum  nuchae.  The 
cervical  spinous  processes  are  very  short,  except  those  of  the  sixth 
and  seventh,  especially  the  latter,  and  in  this  way  backward  flexion 
or  over- extension  of  the  neck  is  not  interfered  with. 

The  articular  processes  spring  from  the  junction  of  the  pedicle 
and  lamina  at  either  side.  Each  is  nearly  circular,  the  plane  being 
oblique,  and  the  surface  almost  flat.  The  superior  pair  look 
backwards  and  upwards,  and  the  inferior  pair  forwards  and 
downwards. 

The  transverse  processes  (diapophyses)  spring  at  either  side  from 
the  junction  between  the  pedicle  and  lamina,  and  are  serially 
homologous  with  the  transverse  processes  of  a  thoracic  vertebra. 
Each  terminates  in  a  projection,  known  as  the  posterior  tubercle. 

The  costal  processes  {pleurapophyses)  project  .outwards  from 
either  side  of  the  body  anteriorly,  and  are  serially  homologous  with 
the  vertebral  part  of  a  rib.  Each  terminates  in  a  projection,  known 
as  the  anterior  tubercle,  which,  with  the  posterior  tubercle  of  the 
corresponding  transverse  process,  gives  attachment  to  the  inter- 
trans  ver  sales  muscles. 

The  transverse  and  costal  processes  are  connected,  at  a  short 
distance  from  the  body,  by  a  plate  of  bone,  called  the  costo-trans- 
verse  lamella,  which  is  deeply  grooved  superiorly  for  a  spinal  nerve, 
this  groove  being  continuous  with  the  superior  vertebral  notch. 
There  is  thus  formed,  at  either  side,  an  aperture,  called  the  costo- 
transverse foramen.  This  foramen  is  circular,  vertical  in  direc- 
tion (except  in  the  case  of  the  axis),  and  it  transmits  the  following 
structures  :  the  vertebral  artery  ;  the  vertebral  plexus  of  veins ; 
and  the  vertebral  sympathetic  plexus  of  nerves.  Though  the 
foramen  is  present  in  each  transverse  process,  it  does  not  give 
passage  to  the  foregoing  structures  in  the  case  of  the  seventh. 
The  vertebral  vein,  however,  may  pass  through  it.  In  many  cases 
an  additional  foramen  of  small  size  is  present  on  one  or  both  sides, 
lying  behind  the  main  foramen,  and.  when  this  is  so,  it  transmits  a 
small  vein.  The  costo-transverse  foramina  of  either  side,  when  in 
position,  build  up  a  canal,  which  is  open  in  each  intertransverse  space. 

The  neural  foramen  is  situated  behind  the  body,  and  is  triangular, 
with  the  angles  rounded  off.  It  is  of  larger  size  than  in  the  thoracic 
or  lumbar  vertebrae,  its  direction  is  vertical,  and  it  lodges  the  spinal 
cord  with  its  membranes. 

The  Atlas. — The  atlas  is  the  first  cervical  vertebra,  and  is  so 
named  because  it  supports  the  head.  Its  distinctive  characters  are 
the  absence  of  a  body  and  spinous  process.  It  has  the  form  of  a 
ring,  narrow  in  front  and  wide  behind,  and  its  component  parts 


THE  BONES  OF  THE   TRUNK 


15 


are  as    follows  :   an   anterior  arch  :   a  posterior  arch ;    two  lateral 
masses ;  and  a  ring. 

The  anterior  arch  is  a  curved  plate  of  bone  which  connects  the 
antero-internal  parts  of  the  lateral  masses.  It  is  compressed  from 
before  backwards,  convex  in  front,  and  concave  behind.  The 
anterior  surface  presents  at  its  centre  a  conical  prominence,  called 
the  anterior  tubercle.  This  gives  attachment  at  either  side  to  a 
portion  of  the  longus  colli  muscle,  and  its  central  part  receives 
the  accessory  ligament.  The  posterior  surface  presents  at  its 
centre  a  circular  concave  facet,  called  the  odontoid  facet,  for  articu- 
lation with  the  anterior  surface  of  the  odontoid  process  of  the 
axis.     The  upper  border  gives  attachment  to  the  anterior  occipito- 


Anterior  Tubercle 


,  Odontoid  Facet 


Tubercle  for  Trans\erse  Ligament 
Costal  Pi  0(  L-.S 


Superior  Articular  Process 


Costo-transverse 
Foramen 


Transverse  Process 


Vertebrarteria!  ^ 
Groove 


Posterior  Tubercle 


Fig.  8. — The  Atlas  (Superior  View). 

(The  Vertebrarterial  Groove  on  this  bone  was  converted  into  a  Foramen  on 

both  sides.) 

atlantal  ligament,  and  the  lower  to  the  anterior  atlanto-axial  liga- 
ment. 

The  posterior  arch  is  serially  homologous  with  the  laminae  of 
other  vertebrae.  It  springs  at  either  side  from  the  back  part  of  a 
lateral  mass,  from  which  it  sweeps  backwards  and  inwards.  The 
part  close  to  the  lateral  mass  at  either  side  is  flattened  from  above 
downwards.  It  presents  on  its  upper  surface  a  shallow  depression, 
called  the  vertebrarterial  groove,  which  lodges  the  vertebral  artery 
and  suboccipital  nerve.  This  groove  is  sometimes  converted  into 
a  foramen  on  one  or  both  sides  by  a  spiculum  of  bone  extending 
frf)m  the  back  part  of  the  su])erior  articular  process  to  the  posterior 
arch  behind  the  groove.  The  vertebrarterial  groove  is  serially 
homologous  with  the  superior  vertebral  notch  of  other  vertebrae, 
but,  unlike  them,  it  lies  behind  the  superior  articular  i)rocess.  The 
inferior  surface  of   the  posterior  arch,  behind  each  lateral   mass, 


i6 


A  MANUAL  OF  ANATOMY 


presents  a  shallow  vertebral  notch,  which  lies  behind  the  inferior 
articular  process.  The  centre  of  the  posterior  arch  presents  the 
'posterior  tubercle,  which  is  the  only  representative  of  a  spinous 
process.  At  either  side  of  this  tubercle  the  rectus  capitis  posticus 
minor  arises.  The  upper  aspect  of  the  posterior  arch  gives  attach- 
ment to  the  posterior  occipito-atlantal  ligament,  and  the  lower 
aspect  to  the  posterior  atlanto-axial  ligament. 

The  lateral  masses  support  the  superior  and  inferior  articular  pro- 
cesses, and  laterally  the  transverse  and  costal  processes  spring  from 
them.  The  anterior  surface  of  each  gives  partial  origin  to  the  rectus 
capitis  anticus  minor.  The  internal  surface  of  each  presents  anteriorly 
a  tubercle  for  the  transverse  ligament.  The  superior  articular  pro- 
cesses are  oval  and  deeply  concave,  to  articulate  with  the  con- 
dyles of  the  occipital  bone.     Their  long  axes  are  directed  backwards 

Anterior  Avch 


Inferior  Articular 
Process 


Inferior  Vertebral 
Notch 


Posterior  Arch 


Fig.    9. — The  Atlas  (Inferior  View). 

and  outwards,  so  that  they  converge  in  front  and  diverge  behind. 
Anteriorly  they  reach  as  far  as  the  anterior  arch,  and  posteriorly 
they  overhang  the  vertebrarterial  grooves  on  the  posterior  arch 
to  a  slight  extent,  but  they  do  not  extend  farther  back  than 
about  the  centre  of  the  ring.  The  plane  of  each  is  sloped  down- 
wards and  inwards,  and  the  direction  of  the  surface  is  upwards 
and  inwards.  The  movement  between  them  and  the  occipital 
condyles  is  one  of  flexion  and  extension,  or  nodding.  Some- 
times one  or  both  of  them  may  be  divided  by  a  groove  into  two 
circular  facets.  The  inferior  articular  processes  are  circular  and 
slightly  concave.  The  plane  of  each  is  sloped  upwards  and  in- 
wards, and  the  direction  of  the  surface  is  downwards  and  inwards. 
They  articulate  with  the  superior  articular  processes  of  the  axis, 
and  the  movement  allowed  is  rotation.  The  articular  processes 
of  the  atlas,  being  placed  in  front  of  the  points  of  exit  of  the  spina 


THE  BONES  OF  THE  TRUNK  17 

nerves,  do  not  correspond  in  position  with  the  articular  processes 
of  succeeding  vertebrae  (with  the  exception  of  the  superior  pair 
of  the  axis).  They  occupy  a  position  corresponding  with  the 
pedicular  portions  of  the  bodies  of  vertebrae,  and  in  this  way 
the  superincumbent  weight  is  transmitted  to  the  vertebral 
bodies. 

The  transverse  and  costal  processes  spring  from  the  side  of  each 
lateral  mass,  and,  external  to  the  costo-transverse  foramen,  the 
costo-transverse  lamella  and  the  anterior  and  posterior  tubercles 
are  more  or  less  fused  into  one  long  irregular  mass,  though  the 
posterior  tubercle  usually  remains  conspicuous.  The  upper  surface 
of  this  mass  at  its  front  part  gives  origin  to  the  rectus  capitis 
lateralis,  and  at  its  back  part  to  the  obliquus  capitis  superior, 
whilst  the  lower  surface  at  its  back  part  gives  insertion  to  the 
obliquus  capitis  inferior.  The  costo  -  transverse  foramen  is  of 
large  size  in  order  to  guard  against  the  vertebral  artery  being 
compressed  during  the  rotatory  movements  of  the  bone  upon  the 
axis. 

The  ring  of  the  atlas,  in  the  recent  state,  is  divided  into  two  com- 
partments by  the  transverse  ligament.  The  anterior  small  division 
is  called  the  odontoid  compartment,  and  it  lodges  the  odontoid  pro- 
cess of  the  axis.  The  posterior  large  division  represents  the  neural 
foramen  of  other  vertebrae,  and  it  lodges  the  spinal  cord  with  its 
membranes. 

Varieties. — (i)  The  posterior  arch  may  be  incomplete  at  the  centre,  the 
deficiency  being  bridged  over  by  fibrous  tissue.  (2)  The  costal  process  may 
be  incomplete,  the  deficiency  in  the  costo-transverse  foramen  being  filled  by 
fibrous  tissue.  (3)  There  is  sometimes  an  additional  small  foramen  on  either 
side,  a  little  behind  the  costo-transverse  foramen,  for  the  passage  of  the  sub- 
occipital radicles  of  the  vertebral  plexus  of  veins. 

The  Axis. — The  axis  is  the  second  cervical  vertebra,  and  is 
so  named  because  its  odontoid  process,  which  is  the  distinctive 
character  of  the  bone,  forms  a  pivot  on  which  the  atlas,  support- 
ing the  head,  rotates.  From  the  presence  of  this  process  the  axis 
is  sometimes  called  the  vertebra  dentata. 

The  odontoid  process  {processus  dentatus)  springs  from  the 
superior  surface  of  the  body,  and  represents  the  body  of  the  atlas. 
It  is  constricted  and  somewhat  circular  close  to  the  body,  this  part 
being  called  the  neck.  Above  this  it  expands  into  a  head,  which 
tapers  off  at  either  side  by  two  sloping  surfaces,  forming  by  their 
convergence  an  antero-posterior  ridge,  known  as  the  summit. 
The  anterior  surface  presents  a  circular  convex  facet,  called  the 
allantal  facet,  for  articulation  with  the  odontoid  facet  on  the  posterior 
surface  of  the  anterior  arch  of  the  atlas.  The  posterior  surface 
presents  a  shallow  transverse  groove  for  the  play  of  the  transverse 
ligament  of  the  atlas.  The  lateral  sloping  surfaces  on  cither  side 
of  the  summit  give  attachment  to  the  latcrjd  odontoid  ligeunents, 
whilst  the  summit  itself  gives  attachment  to  the  middle  odontoid 
ligament. 

2 


i8 


A  MANUAL  OF  ANATOMY 


The  superior  surface  of  the  body  is  occupied  by  the  odontoid 
process  and  portions  of  the  superior  articular  processes.  The 
inferior  surface  differs  from  that  of  other  cervical  vertebrae  only 
in  the  greater  downward  projection  of  its  anterior  lip.  The  anterior 
surface  presents  a  median  vertical  ridge  which  bifurcates  inferiorly 
into  diverging  lips,  enclosing  a  small  triangular  surface.  On  either 
side  of  the  median  ridge  the  surface  is  depressed,  and  gives 
attachment  to  a  portion  of  the  longus  colli  muscle.  The  other 
surfaces  of  the  body  present  nothing  peculiar. 

The  pedicles  are  concealed  above  by  the  superior  articular  pro- 
cesses. Each,  on  its  inferior  aspect,  presents  a  wide  and  deep 
inferior  vertebral  notch,  which  is  placed  in  front  of  an  inferior  articular 
process.  The  superior  vertebral  notches,  which  are  very  shallow, 
are    situated    on    the    upper    borders    of    the    laminae,    and,    like 


Atlantal  Facet 

Odontoid  Process 

Groove  for  Transverse  Ligament 


■r,    ,  1   Inferior 

Body  I     Notch 

Costo-transverse  Foramen 


Spine 


Fig.  io. 


Inferior  Articular  Process 

-The  Axis  (Lateral  View). 


those  of  the  atlas,  are  placed  behind  the  superior  articular  pro- 
cesses. 

The  laminae  are  massive,  and  give  attachment  by  their  upper 
borders  to  the  posterior  atlanto-axial  ligaments,  whilst  their 
anterior  surfaces,  near  the  lower  borders,  give  attachment  to 
ligamenta  subfiava,  as  in  other  vertebrae. 

The  spinous  process,  though  short,  is  massive.  Its  direction  is 
backwards,  and  it  terminates  in  two  strong  tubercles,  separated 
inferiorly  by  a  triangular  cleft.  Each  of  these  tubercles  gives 
attachment  to  some  of  the  deep  fibres  of  the  ligamentum  nuchae, 
and  to  the  following  muscles  from  above  downwards  :  the  rectus 
capitis  posticus  major ;  the  obliquus  capitis  inferior ;  and  the 
highest  portion  of  the  semispinalis  colli. 

The  superior  articular  processes  are  situated  on  the  upper  surface 
of  the  pedicle  at  either  side,  the  upper  surface  of  the  costal  pro- 
cess, and  a  portion  of  the  superior  surface  of  the  body,  upon  which 


TtiE  BONES  OF  THE  TRUNK 


i9 


Tatter  it  encroaches  very  near  to  the  odontoid  process.  The  plane 
of  each  is  sloped  outwards  and  downwards.  The  surface  is  slightly 
convex  from  before  back- 
wards and  circular,  its  direc- 
tion being  upwards  and  out- 
wards. They  articulate  with 
the  inferior  articular  pro- 
cesses of  the  atlas,  and  the 
movement  allowed  is  rota- 
tion. The  inferior  articular 
processes  differ  from  those 
of  most  vertebrse  only  in 
being  s'.tua+.ei  principally 
upon  the  lower  borders  of 
the  laminae.  The  superior 
pair,  like  all  four  articular 
processes  of  the  atlas, 
being  placed  in  front  of 
the  points  of  exit  of  the 
spinal  nerves,  do  not  corre- 
spond in  position  with  the 
superior  articular  processes 
of  succeeding  vertebrae,  but 


Fig.  II. — The  Axis  (Superior  View) 


occupy  a  position  corresponding  with  the  pedicular  portions  of 
the  bodies  of  vertebrae. 

The  transverse  processes  are  very  short,  and  are  directed  out- 
wards and  downwards.     Each  terminates  in  a  single  tubercle. 

The  costal  processes  do  not  terminate  in  tubercles,  and  the  costo- 
transverse lamellae  are  not  grooved  superiorly. 

The  costo-transverse  foramen  is  directed  upwards  and  outwards, 
the  reason  of  this  obliquity  being  as  follows  :  when  the  atlas  and 
axis  are  in  position  each  costo-transverse  foramen  in  the  atlas 
lies  farther  out  than  that  in  the  axis.  In  order,  therefore,  to 
obviate  any  sudden  and  undue  bend  in  the  vertebral  artery,  the 
foramen  in  the  axis  is  directed  obliquely  upwards  and  outwards 
so  as  to  guide  the  vertebral  artery  gradually  to  the  foramen  in  the 
atlas. 

There  is  nothing  peculiar  about  the  neural  foramen- 

Varieties. — (i)  The  summit  of  the  odontoid  process  may  present  a  facet, 
inchcating  an  articulation  with  the  anterior  margin  of  the  foramen  magnum  of 
the  occipital  hone,  wliich  in  such  cases  presents  a  prominence  known  as  the 
middle  occipital  condyle.  (2)  The  odontoid  ])rocess  may,  in  very  rare  cases, 
remain  sejjarate  from  the  body,  thus  forming  the  os  dentatiim.  (3)  An 
oflontoifl  process  in  two  halves  has  been  recorded. 

The  seventh  cervical  vertebra. — ^The  distinctive  character  of  this 
vertebra  is  tlu;  greitt  length  of  its  s])inous  ])rocess,  which  is  the  only 
cervical  sj)ine  that  can  readily  l)c  felt  beneatli  the  integument  of 
the  neck.  On  account  of  this  (outstanding  ])romincnce  the  seventh 
cervical  is  known  as  the  vertebra  prominens.     The  spinous  process 

2 — 2 


20 


A  MANUAL  OF  ANATOMY 


is  directed  straight  backwards,  and  terminates  in  a  single  large 
tubercular  eminence.  The  other  characters  of  this  vertebra  to 
be  noted  are  as  follows  :  the  antero-posterior  measurement  of 
the  body  exceeds  that  of  other  cervical  vertebrae  ;  the  trans- 
verse process  is  massive  and  comparatively  long  ;  the  posterior 
tubercle  is  very  distinct,  but  the  anterior  is  rudimentary,  or 
wanting  ;  the  costo-transverse  foramen  is  of  small  size,  and  does 
not  transmit  the  vertebral  vessels  and  vertebral  sympathetic 
plexus.     The  vertebral  vein,  however,  may  pass  through  it. 

Varieties. — (i)  The  costal  process  may  remain  separate  from  the  transverse 
process,  thus  giving  rise  to  a  cervical  rib.  (2)  The  costal  process  may  be 
wanting  on  one  or  both  sides,  in  which  cases  there  is  no  costo-transverse 
foramen. 


Fig.  12. — The  Seventh  Cervical  Vertebra  (Superior  View). 

(The  Costal  Process  of  the  Left  Side  was  undeveloped  in  this  vertebra.) 

It  is  to  be  noted  that  the  sixth  cervical  vertebra  is  peculiar  in  the 
following  respects  :  the  spinous  process,  like  that  of  the  vertebra 
prominens,  terminates  in  a  single  large  tubercular  eminence ; 
and  the  tubercle  of  each  costal  process,  known  as  the  anterior 
tubercle,  is  of  large  size,  and  is  called  the  carotid  tubercle  of  Chas- 
saignac. 

The  cervical  vertebrae  receive  their  blood-supply  from  branches 
of  the  vertebral  arteries. 


The  Thoracic  Vertebrae. 


The  thoracic  vertebrse  are  twelve  in  mrniber,  and  their  distinctive 
character  is  the  presence  of  one  or  more  facets  on  either  side  of 
the  bodies   for  articulation  with   the   heads   of  ribs.     The   first. 


THE  BONES  OF  THE  TRUNr<  21 

tenth,  eleventh,  ard  twelfth  (sometimes  also  the  ninth)  are  peculiar, 
and  require  separate  descriptions. 

A  Typical  Thoracic  Vertebra.— The  body  is  larger  than  that  of 
a  cervical  vertebra,  but  smaller  than  that  of  a  lumbar.  When 
viewed  from  above  or  below  it  is  cordate  or  heart-shaped,  being 
broad  ard  hollowed  out  behind,  ard  narrow  and  rounded  off  in 
front.  The  posterior  depth  of  the  body  exceeds  the  anterior,  in 
adaptation  to  the  backward  curve  of  the  vertebral  column  in  the 
thoracic  region.  The  superior  and  inferior  surfaces  present  a  raised 
rim  round  the  circumference,  due  to  the  annular  circumferential 
epiphysis,  and  this  renders  the  whole  of  each  surface  slightly  con- 
cave from   the  periphery  towards  the  centre.     The  anterior  and 

Superior  Articular  Process  ^ 
Superior  Notch 

Superior  Demi-facet\  ^     vr    »,■,« 

Costo-tubercular  Facet 


Inferior  Articular  Process- 


Fig.   13. — The  Sixth  Thoracic  Vertebra  (Lateral  View). 


lateral  surfaces  merge  gradually  into  each  other,  and  are  con- 
cave from  above  downwards,  the  entire  antero-lateral  surface 
being  convex  from  side  to  side  and  pierced  by  numerous  nutrient 
foramina.  Each  lateral  surface,  close  to  the  neural  arch,  presents 
two  articular  demi-facets,  superior  and  inferior,  of  which  the 
superior  is  the  larger,  and  is  situated  upon  the  pedicular  portion  of 
the  body,  the  inferior  smaller  one  being  just  in  front  of  the  lower 
part  of  the  inferior  vertebral  notch.  These  demi-facets  are  for 
articulation  with  the  heads  of  the  ribs,  and  are  called  the  costo- 
capitular  facets.  When  two  vertebra-  are  in  jwsition  the  superior 
demi-facet  of  the  lower  vertebra  and  the  inferior  dcmi-facet  of  the 
upper  form  an  articular  cavity  for  the  head  of  a  rib.  The  posterior 
surface  of   the  body  is  concave  from  side  to  side,  and  ])resents 


22  A  MANUAL  OF  ANATOMY 

nutrient  foramina,  as  in  the  cervical  vertebrae.  The  superior 
and  inferior  surfaces  are  related  to  the  intervertebral  discs,  and  the 
anterior  and  posterior  surfaces  are  related  to  the  anterior  and 
posterior  common  ligaments. 

The  pedicles  spring  from  either  lateral  extremity  of  the  posterior 
surface  of  the  body,  and  their  upper  borders  are  very  nearly  on  a 
level  with  its  superior  surface.  Each  pedicle  is  laterally  compressed, 
and  is  directed  backwards  and  slightly  outwards.  The  sviperior 
vertebral  notches  are  shallow,  and  each  is  usually  bounded  in 
front  by  a  transverse  lip.  The  inferior  vertebral  notches  are  deep 
and  wide. 

The  laminae  are  short,  deep,  and  compressed  from  before  back- 
wards, their  planes  being  sloped  downwards  and  backwards.     The 


Pedicle 


Superior  Articular 
Process 


Fig.  14. — The  Sixth  Thoracic  Vertebra  (Superior  View). 


markings  for  the  ligamenta  subfiava  are  the  same  as  in  cervical 
vertebrae. 

The  spinous  process  is  triangular  or  bayonet-shaped.  Its  direc- 
tion is  downwards  and  slightly  backwards,  and  it  terminates  in 
a  sloping  border  ending  below  in  a  sharp  point.  The  spinous 
processes  of  the  central  thoracic  vertebrae  are  imbricated  or  over- 
lapping. 

The  articular  processes  are  nearly  circul  r,  their  surfaces  are 
flat,  and  their  planes  are  almost  vertical.  The  superior  fair  pro- 
ject upwards  from  the  junction  between  the  pedicles  and  laminae, 
and  they  look  backwards  and  slightly  upwards  and  outwards. 
The  inferior  pair  are  placed  on  the  anterior  surfaces  of  the 
laminae,  and  they  look  forwards  and  slightly  [downwards  and 
inwards^ 


THE  BONES  OF  THE  TRUNK  23 

The  transverse  processes  spring  from  the  junction  of  the  pedicles 
and  lamime,  and  each  is  directed  outwards  and  backwards.  They 
are  long  and  club-shaped,  being  somewhat  constricted  at  their 
bases,  but  expanding  into  knob-like  enlargements  at  their  ex- 
tremities. The  anterior  surface  of  the  extremity  of  each  presents 
a  circular  concave  facet,  called  the  costo-tuhercular  facet,  for  articula- 
tion with  the  tubercle  of  a  rib.  The  posterior  surface  of  the 
extremity  gives  attachment  to  the  posterior  costo  -  transverse 
ligament.  The  anterior  surface  of  the  transverse  process  faces 
the  posterior  surface  of  the  neck  of  a  rib,  and  gives  attachment  to 
the  middle  costo-transverse  or  interosseous  ligament.  This  region 
corresponds  with  the  costo-transverse  foramen  in  a  cervical  vertebra. 
The  lower  border  of  the  transverse  process  gives  attachment  to 
the  superior  costo-transverse  ligament,  which  connects  it  with 
the  crest,  or  upper  border  of  the  neck,  of  the  rib  below.  The 
transverse  process  is  serially  homologous  with  a  cervical  transverse 
process. 

The  neural  foramen  is  almost  circular,  and  is  of  smaller  size  than 
in  the  cervical  or  lumbar  vertebrae. 

Peculiar  Thoracic  Vertebrae. — These  are  the  first,  tenth,  eleventh, 
and  twelfth  (sometimes  also  the  ninth). 

The  First  Thoracic  Vertebra. — ^This  vertebra  closely  resembles  the 
seventh  cervical,  as,  indeed,  do  one  or  two  below  it.  Its  distinctive 
character  is  the  presence  on  each  side  of  the  body  of  one  entire  facet 
close  to  the  upper  part,  and  situated  on  the  pedicular  portion,  for  the 
head  of  the  first  rib,  and  one  demi-facet  close  to  the  lower  part  for 
a  portion  of  the  head  of  the  second  rib.  With  the  exception  of  the 
inferior  articular  and  transverse  processes,  this  vertebra  in.  other 
respects  closely  corresponds  with  the  seventh  cervical,  with  this 
difference,  that  the  antero-posterior  lips  of  the  superior  surface  of 
the  body  of  the  seventh  cervical  are  replaced  by  transverse 
lips  lying  in  front  of  the  superior  vertebral  notches.  The 
inferior  articular  and  transverse  processes  are  similar  to  those 
of  a  typical  thoracic  vertebra,  each  transverse  process  having 
the  usual  costo  -  tubercular  facet  on  the  anterior  surface  of  its 
extremity. 

The  Tenth  Thoracic  Vertebra.— This  vertebra  has  usually  one 
entire  facet  on  either  side,  mainly  on  the  pedicle,  for  the  head  of 
the  tenth  rib.  This  facet,  however,  may  only  be  a  three-quarter 
facet,  if  the  ninth  thoracic  vertebra  is  normal.  It  has,  usually,  a 
costo-tubercular  facet  on  the  anterior  aspect  of  the  extremity  of 
each  transverse  process  for  the  tubercle  of  the  tenth  rib,  but  this 
facet  may  be  wanting.  The  body  and  spinous  process  of  this 
vertebra  show  indications  of  the  lumbar  type,  its  other  characters 
being  thoracic. 

Tlie  Eleventh  Thoracic  Vertebra. — This  vertebra  has  an  entire 
facet  on  the  outer  surface  of  each  pedicle  for  the  head  of  the  eleventh 
rib,  but  there  is  no  facet  on  the  transverse  process,  which  has  become 
short  and  stunted,  the  tendency  to  the  club  shape  being,  however, 


24 


A   MANUAL  OF  ANATOMY 


still  perceptible.     The  lumbar  type  of  the  bone  is  more  pronounced 
than  in  the  case  of  the  tenth. 

The  Twelfth  Thoracic  Vertebra.— This,  like  the  eleventh,  has  an 
entire  facet  on  the  outer  surface  of  each  pedicle  for  the  head  of  the 


Superior  Tubercle 

-—External       do. 
Inferior         do. 


Mammillary  Process 
__  Accessory  Process 


Transverse  Process 

Fig.    15. — The   Peculiar  Thoracic  Vertebrae   and    the   First   Lumbar 

Vertebra. 

twelfth  rib,  and  no  facet  on  the  transverse  process.  The  transverse 
processes  are  very  stunted,  and  each  presents  three  tubercles — 
external,  superior,  and  inferior — a  condition  which  also  manifests 
itself,  though  not  so  conspicuously,  in  the  transverse  processes 
of  the  eleventh,  and  even  the  tenth.     The  external  tubercle,  along 


THE  BONES  OF  THE  TRUNK  25 

with  the  twelfth  rib,  is  serially  homologous  with  a  lumbar  trans- 
verse process,  the  superior  with  a  lumbar  mammillary  process,  and 
the  inferior  with  a  lumbar  accessory  process.  The  superior 
articular  processes  are  thoracic  in  type,  whilst  the  inferior  are  like 
those  of  a  lumbar  vertebra,  being  convex  and  directed  outwards 
and  forwards,  or  away  from  each  other.  Sometimes  the  superior 
articular  processes  are  also  lumbar  in  type,  being  concave  and 
looking  inwards  and  backwards,  or  towards  each  other.  When 
this  is  so,  the  inferior  articular  processes  of  the  eleventh  thoracic 
vertebra  are  also  lumbar  in  type.  The  twelfth  thoracic  vertebra 
very  closely  resembles  a  lumbar  vertebra,  from  which,  how- 
ever, it  differs  in  having  a  facet  on  the  outer  surface  of  each 
pedicle.  If  the  Ninth  Thoracic  Vertebra  is  pecuhar  this  consists  in 
the  absence  of  the  loiejer  demi-facet  on  the  side  of  the  body. 

The  thoracic  vertebrae  receive  their  blood-supply  from  the  inter- 
costal arteries. 

The  Lumbar  Vertebrae. 

The  lumbar  vertebrae  are  five  in  number,  and  are  so  named  because 
they  occupy  the  region  of  the  loins.  They  are  the  largest  of  the 
true  vertebrae,  and  their  negative  characters  are — the  absence  of 
a  costo-transverse  foramen  in  the  transverse  process;  and  the 
absence  of  any  kind  of  costal  facet  on  the  side  of  the  body.  They 
increase  in  size  from  above  downwards,  the  fifth  being  the  largest, 
but,  as  this  vertebra  has  certain  distinctive  characters,  it  will  be 
separately  described. 

A  Typical  Lumbar  Vertebra. — The  body,  when  viewed  from  above 
or  below,  is  reniform,  being  flattened  from  above  downwards, 
convex  transversely  over  its  antero-lateral  surface,  and  slightly 
concave  transversely  on  its  posterior  surface.  It  is  wider  from 
side  to  side  than  from  before  backwards.  The  anterior  depth  is 
slightly  greater  than  the  posterior,  in  adaptation  to  the  forward 
curve  of  the  vertebral  column  in  the  lumbar  region.  The  general 
characters  correspond  with  those  of  the  thoracic  vertebrje. 

The  pedicles  are  short,  strong,  and  directed  backwards.  The 
superior  vertebral  notches  are  shallow,  the  inferior  being  deep  and  wide. 

The  laminae  are  short,  thick,  and  deep,  and  their  planes  are 
almost  vertical. 

The  spinous  process  is  axe-shaped,  its  direction  being  straight 
backwards,  and  it  terminates  in  a  round  elongated  border. 

The  articular  processes  are  strong.  The  superior  pair  project 
upwards  from  the  junction  of  the  pedicles  and  laminae,  and  the 
inferior  pair  project  downwards  from  the  lower  borders  of  the 
lamina.  The  superior  pair  are  concave,  their  planes  being  vertical, 
and  their  direction  being  inwards  and  backwards,  so  that  they  almost 
face  each  other.  They  stand  wide  apart,  so  as  to  embrace  the 
inferior  articular  processes  of  the  vertebra  above.  On  the  posterior 
border  of  each  there  is  a  nipple-shaped  projection,  directed  back- 
wards and  slightly  upwards,  called  the  mammillary  process  {meta- 


26 


A  MANUAL  OF  ANATOMY 


apophysis),  which  corresponds  with  the  superior  tubercle  of  the 
lower  thoracic  transverse  processes.  The  inferior  articular  pro- 
cesses are  convex,  their  planes  being  vertical,  and  their  direction 
being  outwards  and  forwards,  so  that  they  look  away  from 
each  other.  The}^  are  nearer  to  each  other  than  the  superior 
pair,  and  are  embraced  between  the  superior  pair  of  the  vertebra 
oelow. 

Ihe  transverse  processes  are  comparatively  slender,  except  in 
the  case  of  the  fifth;  the}^  are  directed  outwards  and  slightly 
backwards,  and  they  increase  in  length  from  the  first  to  the 
fourth.      Each  is  spatula  -  shaped,  being  compressed  from  before 


Body 


Transverse  Process 

u 

Accessory  Process         j 
Mammillary  Process 


Back  of  Inferior 
Articular  Process 


Superior  Articular  Process 


Fig.  iG. — The  Third  Lumbar  Vertebra  (Superior  View) 


backwards,  and  terminates  in  a  short  round  border.  It  repre- 
sents the  vertebral  portion  of  a  rib,  and  therefore  constitutes 
the  costal  element  of  the  vertebra.'  Situated  on  the  posterior 
aspect  of  the  base  of  the  transverse  process,  just  external  to  and 
below  the  lower  border  of  the  superior  articular  process,  there  is 
a  small  sharp  projection  directed  downwards,  called  the  accessory 
process  (anapophysis),  which  is  the  rudiment  of  the  true  transverse 
process,  and  is  serially  homologous  with  the  inferior  tubercles  of 
the  lower  thoracic  vertebrse  and  the  other  thoracic  transverse 
processes.  In  the  case  of  the  fourth  and  fifth  lumbar  vertebrae 
the  transverse  process  becomes  shifted  on  to  the  pedicle,  and  even 
slightl}^  on  to  the  body.  Between  the  base  of  the  transverse  process 
and   the   accessory  process   posteriorly  there   are   a  few   nutrient 


THE  BONES  OF  THE  TRUNK 


27 


foramina  which  correspond  with  the  costo- transverse  foramen  in 
cervical  vertebrae. 

The  lumbar  transverse  processes  (costal  elements)  of  man  are  serially 
homologous  with  the  ribs,  and  also,  in  the  case  of  the  lower  thoracic  vertebrae, 
with  the  external  tubercles  of  the  transverse  processes.  In  the  lumbar  region 
each  transverse  process  (costal  element)  has  fused  with  the  accessory  process 
(true  transverse  process),  and  so  the  costo-transverse  foramen  in  the  transverse 
process  of  a  cervical  vertebra  is  represented  only  by  a  few  nutrient  foramina. 

The  neural  foramen  is  larger  than  in  the  thoracic  vertebrae,  but 
not  so  large  as  in  the  cervical,  its  shape  being  triangular  with 
rounded  angles. 

The  Fifth  Lumbar  Vertebra. — ^The  distinctive  characters  of  this 


Fig.   17. — The  Fifth  Lumbar  Vertebra  (Superior  View). 

vertebra  are  as  follows  :  (i)  it  is  the  most  massive  of  all  the  lumbar 
vertebrae  ;  (2)  the  greater  d^pth  of  the  body  in  front  is  more  con- 
spicuous than  in  the  others  ;  (3)  the  transverse  processes  are  thick 
and  conical  ;  and  (4)  the  inferior  articular  processes  are  wide 
apart. 

The  lumbar  vertebrae  receive  their  blood-su]-)ply  from  the  lumbar 
arteries. 


Ossification  of  the  True  Vertebrae. 

Each  true  vertebra  ossifies  in  cartilage  from  three  primary,  and  five  secondary, 
centres.  One  primary  centre  is  for  the  principal  i)art  of  the  l)ody,  and  two  are 
for  the  neural  arch  and  its  processes,  including  also  a  small  portion  of  the  body 
at  either  side  adjacent  to  the  pedicle.     The  centres  for  the  neural  arch  appear 


28 


A  MANUAL  OF  ANATOMY 


about  the  seventh  week  of  intra-uterine  life  at  the  junction  of  the  pedicles  and 
laminae,  and  from  these  ossification  invades  the  neural  arch,  with  its  processes, 
and  the  adjacent  portions  of  the  body.  The  centre  for  the  principal  part  of 
the  body  appears  about  the  eighth  week  in  the  portion  of  cartilage  dorsal  to 


Appears  about  the  8th  Week 

Appears  about  the  7th 
Week  of  ", 

intra-uterine 
life 


Neural  Arch 


B 

Body 


Neuro-central 
Svnchondrosis 


Neural  Arch 


Fig.   18. — Ossification  of  the  True  Vertebrae. 

A,  Cervical  Vertebra  at  the  Third  Month  ;     B,  Cervical  Vertebra  at  Birth  ; 
C,  Thoracic  Vertebra  at  Birth. 

the  notochord.  It  is  usually  single  at  first,  but  it  soon  assumes  a  bilobed 
form,  and  so  it  comes  to  surround  the  notochord,  which  becomes  constricted, 
and  ultimately  disappears.  This  nucleus  may  be  double,  and,  if  this  character 
persists,  the  body  ossifies  in  two  separate  parts,  or,  if  one  nucleus  should  be 


Transverse  Epiphysis 
i  (i6th  and  25th  Year) 

Mammillary  Epiphysis 
(i6th  and  2Sth  Year) 


Appears  about  the  i6th,  and 
joins  about  the  25th,  Year 


Spinous  Epiphysis 
(i6th  and  25th  Year) 


Fig.   19. — Lumbar  Vertebra,  showing  the  Epiphyses. 
A,  The  Body ;  B,  The  Neural  Arch. 


arrested,  only  one-half  of  the  body  ossifies  (Turner).  At  birth  a  vertebra  is 
composed  of  three  osseous  parts,  connected  by  cartilage,  namely,  the  principal 
part  of  the  body,  and  the  two  halves  of  the  neural  arch,  each  bearing  a  small 
portion  of  the  body.     The  laminae  unite  behind  in  the  first  year,  except  in  the 


THE  BONES  OF  THE   TRUNK  29 

axis,  where  the  union  is  delayed  until  the  fourth  year,  and  the  neural  arch 
joins  the  body  in  the  third  year.  The  cartilaginous  union  between  the  neural 
arch  and  the  body  at  either  side  is  called  the  neuro-central  synchondrosis.  In 
the  thoracic  vertebrje  the  superior  demi-facets  lie  behind  this,  and  so  they  are 
shown  to  be  placed  on  the  pedicular  portion  of  the  body.  All  vestiges  of  this 
synchondrosis  have  disappeared  prior  tc  the  sixth  year.  The  secondary  centres, 
five  in  number,  appear  about  the  sixteenth  year,  and  they  are  consohdated 
about  the  twenty -fifth  year.  One  appears  at  the  extremity  of  the  spinous 
process,  one  at  the  extremity  of  each  transverse  process,  and  the  other  two 
take  the  form  of  epiphysial  plates,  one  on  the  upper  surface  and  the 
other  on  the  under  surface  of  the  body.  In  the  case  of  the  seventh  cervical 
vertebra,  and  sometimes  one  or  two  above  it,  the  costal  process  has  a 
special  centre  which  appears  before  birth,  and  it  may  be  developed  into 
a  cer\ical  rib.  The  transverse  process  (costal  element)  of  the  first  lumbar 
has  occasionally  a  special  centre,  and  in  these  cases  it  may  be  developed  into 
a  lumbar  rib.  The  lumbar  mammillary  processes  are  ossified  from  special 
secondarv'  centres.  The  fifth  lumbar  has  sometimes  four  centres  for  the 
neural  arch,  two  at  either  side,  one  of  which  is  for  the  pedicle,  transverse 
process,  and  superior  articular  process,  and  the  other  for  the  lamina, 
inferior  articular  process,  and  one-half  of  the  spinous  process.  These  parts 
may  fail  to  unite,  in  which  cases  the  neural  arch  presents  a  synchondrosis 
on  either  side,  situated  between  the  superior  and  inferior  articular  processes 
(Turner).  Sometimes  the  laminae  of  the  fifth  lumbar  fail  to  unite,  and  so  a 
space  is  left,  bridged  over  by  fibrous  tissue. 

The  Atlas. — The  atlas  has  three  centres  of  ossification,  two  for  the  lateral 
masses  and  posterior  arch,  appearing  in  the  seventh  week  of  intra-uterine  life,  and 
one  (sometimes  two)  for  the  anterior  arch,  which  does  not  appear  until  the 


Appears  in  7th  Week 
(intra-uterine) 

Fig.  20. — Ossification  of  the  Atlas. 

first  year.  The  two  halves  of  the  neural  arch  usually  join  towards  the  end  of 
the  third  year,  there  being  sometimes  a  special  osseous  deposit  at  the  place  of 
junction.  The  two  halves,  however,  may  remain  separate  throughout  life, 
the  interval  being  bridged  over  by  fibrous  tissue.  The  anterior  arch  joins 
the  lateral  masses  in  the  sixth  year.  The  anterior  arch  represents  the 
hypochordal  brace  of  the  first  vertebral  bow. 

The  Axis. — Excluding  the  odontoid  process,  the  axis  has  three  primary  centres, 
hke  an  ordinary  vertebra,  two  for  the  neural  arch  appearing  about  the  seventh 
week,  and  one  (sometimes  two)  appearing  in  the  lower  part  of  the  common 
cartilage  of  the  body  and  odontoid  process  in  the  fourth  month.  In  the  upper 
part  of  this  common  cartilage  two  centres,  laterally  disposed,  appear  in  the 
fifth  month  for  the  odontoid  process,  and  these  unite  into  one  centre  about  the 
sixth  month.  At  birth  the  axis  is  composed  of  four  osseous  parts  connected 
by  cartilage,  namely,  a  body,  an  odontoid  process  surmounted  by  cartilage, 
and  two  halves  of  the  neural  arch.  The  odontoid  process  joins  the  body 
about  the  fourth  year.  The  two  halves  of  the  neural  arch  join  each  other, 
and  the  arch  joins  the  body,  in  the  fourth  year.  The  apical  part  of  the  odontoid 
process  has  a  special  centre  appearing  in  the  fourth  year,  and  it  joins  the 
rest  of  the  process  in  the  twelfth  year.  The  body  of  the  axis  has  the  usual 
epiphysial  plate  on  the  under  surface  of  the  body,  but  there  is  no  such  plate 


30 


A   MANUAL  OF  ANATOMY 


on  the  upper  surface.  The  union  between  the  odontoid  process  and  the 
body  is  indicated  by  a  small  cartilaginous  disc  in  the  centre,  which  persists 
until  advanced  life.  The  odontoid  process  is  to  be  regarded  as  the  original 
body  of  the  atlas  for  the  following  reasons:  (i)  in  the  embryo  the  notochord 
^passes  through  its  cartilage;   (2)  the  notochord  presents  a  swelhng  between 


Appears  in  the  2nd 

Year,  and  joins  in 
the  1 2th  Year 


Appear  in  the  5th  Month*' 

and  coalesce  in  the 

6th  Month 


Appears  in  the  .4th 

Month  of 

intra-uterine  life 


Body     Odontoid  Process  (joins  Body 
about  the  4th  Year) 


Fig.  21. — Ossification  of  the  Axis. 
A,  At  the  Fifth  Month;  B,  at  the  Second  Year. 

the  cartilage  of  the  odontoid  process  and  that  of  the  body  of  the  axis,  as  it 
does  in  the  case  of  other  vertebrae ;  (3)  there  is  a  cartilaginous  disc  concealed 
within  the  odontoid  process,  which  is  persistent  until  advanced  life;  (4)  the 
odontoid  process  has  two  primary  centres  of  ossification;  (5)  in  chelonians 
it  forms  a  separate  ossicle;  (6)  a  permanently  separate  odontoid  process 
in  man  has  been  recorded. 


The  False  Vertebrae. 

The  false  vertebrae  are  usually  nine  in  number,  the  upper  five  of 
which  form  the  sacrum,  and  the  lower  four,  the  coccyx. 


The  Sacrum. 

The  sacrum  lies  below  the  fifth  lumbar  vertebra,  and  is  wedged 
in  between  the  ossa  innominata,  where  it  forms  the  greater  part 
of  the  posterior  wall  of  the  pelvis,  its  direction  being  downwards 
and  backwards.  The  sacral  vertebrae  diminish  in  size  from  above 
downwards,  which  renders  the  bone  triangular,  the  base  being 
upwards. 

The  ventral  or  pelvic  surface,  which  is  directed  downwards  and 
forwards,  is  concave  from  above  downwards,  and  from  side  to  side. 
It  presents  along  the  centre  a  solid  mass,  representing  the  ankylosed 
bodies  and  ossified  intervertebral  discs,  which  is  marked  by  four 
transverse  ridges  situated  at  the  places  of  junction.  Superiorly  it 
presents  a  proj  ecting  lip,  called  the  promontory.  On  either  side  there 
is  a  row  of  anterior  sacral  foramina,  four  in  number,  which  diminish 
in  size  from  above  downwards,  and  are  directed  outwards  and  for- 
wards from  the  intervertebral  foramina,  by  means  of  which  they 
communicate  with  the  sacral  canal.  They  transmit  the  anterior 
primary  divisions  of  the  first  four  sacral  nerves. 

The  lateral  masses  are  situated  external  to  the   anterior  sacral 


THE  BONES  OF  THE  TRUNK 


31 


foramina  at  either  side,  and  each  is  marked  anteriorly  by  four 
transverse  grooves,  which  prolong  outwards  the  foramina  and 
lodge  the  transmitted  nerves.  The  pyriformis  muscle  arises  from 
the  front  of  each  lateral  mass  by  three  slips,  which  Sre  inter- 
posed between,  and  lie  external  to,  the  foramina.  The  lateral 
masses  are  formed  by  the  fusion  of  the  pedicles,  transverse  pro- 
cesses, and  costal  elements  of  the  sacral  vertebrae. 


Superior  Articular  Process 


-Uiacus 


Pyriformis 


Inferior  Lateral  Angle 


—    Coccygeus 


4tli  Anterior  Sacral  Foramen 


Fig.  22. — The  Sacrum  (Anterior  Viicw.) 


The  dorsal  surface,  which  is  directed  upwards  and  backwards, 
is  irregularly  convex  and  narrower  than  the  ventral.  In  tlic  middle 
line  it  presents  four  eminences,  which  may  be  distinct,  or  fused  to 
form  a  ridge,  representing  the  spinous  processes  of  the  upj^er  four 
sacral  vertebrae.  The  spinous  process  of  the  fifth  vertebra  is  absent, 
the  development  of  its  laminae  having  been  arrested,  and  there  is 
thus  left  a  triangular  opening,  which  is  the  outlet  of  the  sacral 
canal,  to  be  presently  described.     On  either  side  of  the  median 


32 


A  MANUAL  OF  ANATOMY 


row  of  spines  there  is  a  solid  mass  formed  by  the  ankylosed  laminae, 
which  forms  the  sacral  groove  for  the  origin  of  a  portion  of  the 
multifidus  spinae.  External  to  this  groove  there  is  a  row  of  for- 
amina, four  in  number  at  either  side,  called  the  posterior  sacral 
foramina,  which  are  smaller  than  the  anterior,  and,  like  them, 
diminish  in  size  from  above  downwards.  These  foramina  open 
outwards  and  backwards  from  the  intervertebral  foramina  (by 
which  they  communicate  with  the  sacral  canal),  and  transmit  the 


Rudimentary  Articular  Processes  (fused) 


Superior  Articular  Process 

^  Ligamentous  Surface 

\  Auricular  Surface 


Erector  -  - 
Spinae 


Multifidus  - 
Spinae 


Transverse  Process 
(rudimentary) 

Gluteus  Maximus 


Outlet  of  Sacral  Canal  ,"'' 
Notch  for  5th  Sacral  Nervi 


2nd  Posterior  Sacral 
Foramen 


'^Jnferior  Lateral  Angle 


'  Sacral  Cornu 

Fig.  23. — The  Sacrum  (Posterior  View). 

posterior  primary  divisions  of  the  first  four  sacral  nerves.  It  is 
to  be  noted  that  they  lie  directly  behind  the  anterior  foramina. 
Internal  to  the  posterior  foramina,  and  encroaching  upon  them, 
there  is  a  row  of  small  projections  which  represent  the  articular 
processes  of  the  sacral  vertebrae.  The  lower  pair,  which  belong  to 
the  fifth  sacral  vertebra,  are  prolonged  downwards  as  two  plates 
which  end  in  enlargements.  These  are  called  the  sacral  cornua,  and 
they  are  connected  with  the  cornua  of  the  first  coccygeal  vertebra, 
usually    by   ligaments,    but    sometimes    by    osseous    union.      The 


THE  BOXES  OF  THE  TRUNK 


33 


interval  thus  bridged  over  at  either  side  represents  a  fifth  inter- 
vertebral foramen,  through  which  the  fifth  sacral  nerve  passes. 
The  solid  portion  external  to  the  posterior  foramina  at  either  side 
is  the  lateral  mass,  and  it  presents  a  row  of  four  tubercles,  each  of 
which  is  situated  external  to  a  posterior  foramen.  These  represent 
the  transverse  processes  of  the  lower  four  sacral  vertebrae.  The 
boundaries  of  the  triangular  outlet  of  the  sacral  canal  are  the  spine 
of  the  fourth  sacral  vertebra  above,  and  the  imperfect  laminae 
of    the    fifth    sacral    and    the   sacral   cornua   at   either   side.      It 


Promontory 


Auricular  Surface  -  - 


ist  Spine 
Ligamentous  Surface 


.Sacral  Cornii 

Tip  of  Coccyx  ,  ^^   ;M-y         Coccygeal  Cornu 


Fig.   24. — The  Sacrum  (Left  Lateral  View). 

transmits  the  fifth  pair  of   sacral  nerves  and   the  two  coccygeal 
nerves. 

The  lateral  surface  is  broad  above  and  narrow  below.  The  upper 
part  is  divided  into  two  portions — articular  and  non-articular. 
The  articular  division,  anterior  in  position,  is  covered  by  cartilage, 
and  Ls  shaped  like  an  ear,  on  which  account  it  is  called  the  auricidar 
surface.  It  articulates  with  the  iliac  portion  of  the  os  innominatum, 
and  extends  over  at  least  the  first  two  sacral  vertebne.  The  non- 
articular  division,  posterior  in  i)osition,  is   rough   and  irregular  for 

3 


34 


A   MANUAL  OF  ANATOMY 


the  attachment  of  the  posterior  sacro-iliac  ligament,  and  it  is  known 
as  the  ligamentous  stir  face.  The  lower  part  of  the  lateral  surface 
corresponds  with  at  least  the  lower  two  sacral  vertebrae,  and  may 
include  more  or  less  of  the  third.  It  gives  attachment  to  fibres 
of  the  great  and  small  sacro-sciatic  ligaments  and  a  portion  of  the 
coccygeus  muscle,  whilst  the  adjacent  portion  of  the  posterior 
aspect  gives  origin  to  fibres  of  the  gluteus  maximus.  Inferiorly 
the  lower  part  is  thinned  away  to  a  mere  margin,  and  presents  a 
process,  called  the  inferior  lateral  angle.  Below  this  is  the  trans- 
verse process  of  the  first  coccygeal  vertebra  when  that  is  in  position, 
a  notch  being  thus  formed  on  the  side  of  the  fifth  sacral  vertebra. 
The  inferior  lateral  angle  inclines  towards  the  coccygeal  transverse 
process,  with  which  it  is  usually  connected  by  a  ligament,  though 
in  some  cases  the  two  processes  become  ankylosed.  There  is  thus 
constructed  a  fifth  anterior  sacral  foramen  at  either  side  for  the 

Body 


--s-'-.f_  Transverse 
Process 


Articular  Process, 

with  Mammillary 

Process 


Sacral  Canal 


Spine 


Fig.  25. — The  Base  of  the  Sacrum. 


passage  of  the  anterior  primary  division  of  the  fifth  sacral 
nerve. 

The  base  presents  a  central  and  two  lateral  divisions.  The 
central  division  corresponds  in  its  characters  with  the  superior 
surface  of  a  lumbar  vertebra.  Each  superior  vertebral  notch 
lodges  a  fifth  lumbar  spinal  nerve,  and  the  superior  articular  pro- 
cesses stand  wide  apart.  The  lateral  divisions  of  the  base  are 
called  the  alee.  Each  ala  is  triangular  with  the  apex,  which  repre- 
sents the  transverse  process,  directed  backwards.  The  alar  surface 
is  depressed,  concave  from  side  to  side,  and  convex  from  behind 
forwards.  It  gives  attachment  to  fibres  of  the  iliacus,  the  lateral 
lumbo-sacral  and  anterior  sacro-iliac  ligaments,  and  it  supports  the 
lumbo-sacral  nervous  cord  and  the  internal  iliac  vessels.  The  ala 
is  formed  by  the  fusion  of  the  pedicle,  transverse  process,  and  costal 
element  of  the  first  sacral  vertebra. 

The  apex   is   transversely  oval,   and  articulates  with   the  first 


THE  BONES  OF  THE  TRUNK 

coccygeal    vertebra,    with    the    intervpntir^r,    ^f  •   ^ 

d,sc  until  advanced'Hfe.  when  al^lo^tTes  pla«    '""^""'^^ral 

sJ^i'^ltT^l  "rule"'1?  "t""'  "{«  ^°h  "'  "«  fi«t  four 
somewhat  ct^en?ic"beW.  t's^Sldt  front U'T'"  ^^'1  ""' 
bodies,  and  behind  by  the  ankvlosed  laming  A^  ankylosed 
it  presents  four  „>terve^rtebral  S  „a  ?o"  ?he  passa2  o'f'n^  """ 
These  are  bounded  externally  by  the  lateral  mas^.Sf  "* 'X'™^- 
on  the  ventral  and  dorsal  sirfa^es  by  the  aXlo  and''?„,?P™' 
sacral  foramma.  which  represent  the  ifmbs  ol  a  cap"  al  V  ?he  ^^x 


Appears  about  the  i6th  Year,  and 
joins  about  the  25th  Year 

\  ^,Appear  in  the  3rtl  Month  of 

:  -C  "itra-uterine  life 

A  i  , '// 

— J- 


Appear  alraut  the  i8th  I        v|M^^^^^^3|    ^["r*  Appear  about  the  6th  Month 
Year,  and  join  about 


the  25th  Year 


■  Appear  after  the  5th  Montli 
Neural  Arch 

,  Transverse  Process 
I — Costal  Process 


Body 

Fig.   26.— Ossification  of  the  Sacrum 
A.  Anterior  View  ;  B,  First  Sacral  Vertebra  in  early  Hfe  (Superior  View). 

of  which  corresponds  with  an  intervertebral  fnn,Ti«r.      t^u 

of  the  canal  are  the  sacral  and  coccygeal  r^^ves    and  11^7" 

terminale  of  the  spinal  cord  nerves,  and  the  filum 

miSkfacTaSirs'  "'  '"°°<'-l'P'>'  '™™  "«  -ateral  sacral  and 

Articulations.— 5 M/)mr>r/v  with   the  fifth   inT-.-,].n^        ^  i 
fenorly  with  the  coc^x,  an?!  ..  ..  J^.J^ J^ Ss  tn^^^u^^" 

^o.:?^'^*^j\n^rs:!,°:-:^;xt^tKi^^    -T  --^^ 

coccygeal  vertebra,  or  sometimes  tlie  a  tl       ubar      Th      ,''°'''^'°"  ""^  ^^^^  ^''^ 
to  the  fifth  sacral  vertel,ra  forming    i  n  rf  n    \u  ''^^rease  may  be  due 

forming  a  sixth  lumbar.     (2    The  bodies  of  tlu       T^'T'  °'  '?  '^''  ''''''  «^"a' 
.nay  remain  permanently  separat         fm,  Jh    ml^    1  and  second  sacral  vertebra,- 
their  other  parts.      (3)  tL  S  sa^r  r^?^'    jUikylos.s  has  taken  place  in  all 
1  UJ  lirst  sacral  veitebra  may  be  normal  on  one  side 


3—2 


36  A   MANUAL  OF  ANATOMY 

but  on  the  other  side  it  may  remain  separate  from  the  second,  and  present  the 
characters  of  a  fifth  lumbar.  (4)  The  number  of  sacral  spines  may  be  reduced 
from  four  to  three,  two,  or  one,  or  they  may  be  entirely  absent.  As  a  con- 
sequence of  this,  the  sacral  canal,  which  usually  opens  on  the  back  of  the  fifth 
sacral  vertebra,  may  do  so  on  the  back  of  the  fourth,  third,  second,  or  first, 
so  that  in  some  cases  it  may  be  entirely  open  posteriorly.  (5)  The  sacrum  is 
liable  to  much  variety  as  regards  the  extent  of  its  vertical  curve. 

Characters  of  the  Female  Sacrum. — In  the  female  the  sacrum  is 
smoother,  shorter,  broader,  less  curved,  and  is  set  more  backwards 
than  in  the  male. 

Ossification. — The  sacrum  ossifies  in  cartilage  from  thirty-five  centres. 
Each  segment  has  three  primary  centres,  one  for  the  body  and  two  for  the 
neural  arch.  The  centre  for  the  body  appears  in  the  third  month  of  intra- 
uterine life  in  the  case  of  the  first  three,  and  after  the  pfth  month  in  the  last 
two.  The  centres  for  the  neural  arches  appear  about  the  sixth  month.  The 
neural  arches  join  the  bodies,  in  order  from  below  upwards,  from  the  second 
to  the  sixth  year.  The  union  of  the  laminae  takes  place  from  the  eighth  to 
the  twelfth  year.  It,  however,  fails  in  the  lowest,  and  sometimes  in  those  liigher 
up.  The  anterior  parts  of  the  lateral  masses  of  the  first  three  vertebrae,  which 
represent  the  costal  elements,  have  separate  centres,  which  appear  about  the 
sixth  month.  These  join  the  neural  arches  before  uniting  with  the  bodies, 
the  latter  union  taking  place  rather  later  than  the  union  between  the  neural 
arches  and  the  bodies.  Each  vertebra  has  two  annular  circumferential 
epiphysial  plates,  superior  and  inferior,  which  begin  to  ossify  about  the  sixteenth 
year.  On  each  side  of  the  sacrum  there  are  two  epiphyses,  an  upper  for  the 
auricular  surface,  and  a  lower  for  the  sharp  edge  below,  which  appear  about  the 
eighteenth  year.  Consolidation  begins  about  the  eighteenth  year,  and  pro- 
ceeds from  below  upwards,  union  taking  place  earlier  between  the  segments 
of  the  lateral  masses  than  between  the  bodies.  In  the  latter  case  the  ossifica- 
tion invades  the  intervertebral  discs,  but  in  the  former  it  is  direct  union.  The 
union  is  complete  about  the  twenty-fifth  year,  at  which  period  also  the  lateral 
epiphyses  join  the  bone. 

The  Coccyx. 

The  coccyx  is  composed  as  a  rule  of  four  rudimentary  vertebrae, 
and  it  lies  below  the  apex  of  the  sacrum,  which  constitutes  its  only 
articulation.  The  direction  of  the  bone  is  downwards  and  for- 
wards, and  its  elements  diminish  in  size  from  above  downwards. 
It  is  triangular. 

The  first  coccygeal  vertebra  is  compressed  from  before  backwards, 
broad  above,  narrow  below,  concave  in  front,  and  convex  behind. 
The  superior  and  inferior  surfaces  are  transversely  oval,  and  the 
lateral  borders  are  sloped  downwards  and  inwards.  Two  processes 
project  upwards  from  the  dorsal  surface  at  either  side,  called  the 
cornua,  which  articulate  with  the  sacral  cornua,  usually  by  ligaments, 
but  sometimes  directly.  Each  lateral  border  presents,  superiorly, 
a  projection,  called  the  transverse  process,  which  inclines  towards 
the  inferior  lateral  angle  of  the  sacrum,  and  is  usually  connected 
to  it  by  a  ligament,  which  is  sometimes  ossified. 

The  second  coccygeal  vertebra  presents  traces  of  transverse 
processes  and  cornua,  whilst  the  third  and  fourth  are  reduced  to 
mere  nodules. 


THE  BONES  OF  THE  TRUNK 


37 


The  muscvilar  attachments  of  the  coccyx  are  as  follows  :  the 
gluteus  maximus  to  the  back  of  the  upper  three  segments  close  to 
the  lateral  border  ;  the  sphincter  ani  externus  to  the  tip  ;  the 
posterior  fibres  of  the  levator  ani  and  a  portion  of  the  coccygeus 
to  the  lateral  border.     The  great  and  small  sacro-sciatic  ligaments 


Coccygeus 


Levator  Ani 


Cornu 

Transverse  Process 
(rudimentary) 


Transverse  Process 
(rudimentary) 


Cornu 


Gluteus  Maximus 


Sphincter  Ani  Externus 


Cornu  (rudimentary 


Fig.   27. — The  Coccyx. 
A,  Anterior  View  ;   B,  Posterior  View. 

are  partially  attached  to  the  lateral  border  of  the  first  coccygeal 
vertebra. 

The  coccyx  derives  its  blood-supply  from  the  lower  lateral 
sacral  and  middle  sacral  arteries. 

Varieties. — The  number  of  coccygeal  segments  may  be  increased  to  five, 
due  either  to  the  addition  of  an  extra  nodule,  or  to  incorporation  of  the  fiftii 
sacral  segment.  The  number  may  be  reduced  to  three,  due  either  to  incorpora- 
tion of  the  first  coccygeal  segment  with  the  sacrum,  or  to  suppression  of  one  of 
the  nodules. 

Ossification.— The  coccygeal  vertebra;  are  cartilaginous  at  birth.  I-'ach 
has  one  centre,  though  the  first  may  have  two.     The  centre  for  the  first  appears 


38  A   MANUAL  OF  ANATOMY 

in  the  first  year,  that  for  the  second  some  time  between  the  fifth  and  tenth 
year,  that  for  the  third  a  Uttle  before  puberty,  and  that  for  the  fourth  a  little 
after  that  period.  The  union  of  the  segments  takes  place  from  below  upwards, 
the  three  lower  having  usually  joined  by  middle  life.  At  a  later  period  the 
first  segment  joins  the  rest,  and  in  advanced  life  (earlier  in  the  male  than  in  the 
female)  the  coccyx  becomes  ankylosed  to  the  sacrum.  Prior  to  middle  life 
the  segments  are  separated  by  intervertebral  discs. 


The  Vertebral  Column  as  a  Whole. 

The  vertebral  column  supports  the  other  parts  of  the  skeletoq, 
directly  or  indirectly.  Its  average  length  is  about  28  inches  in 
the  male,  and  rather  less  in  the  female.  When  viewed  from  the 
front,  it  presents  four  pyramids.  The  first  extends  from  the  axis 
to  the  seventh  cervical  vertebra,  its  base  being  downwards.  The 
second  extends  from  the  first  to  the  fourth  thoracic  vertebra,  its 
base  being  upwards.  The  tJtird  extends  from  the  fifth  thoracic  to  the 
fifth  lumbar,  its  base  being  downwards.  The  fourth  extends  from 
the  base  of  the  sacrum  to  the  tip  of  the  coccyx.  These  pyramids 
are  due  to  the  differences  in  breadth  of  the  bodies  in  different  parts. 

The  column  presents  certain  curves,  which  are  arranged  in  two 
groups,  antero-posterior  and  lateral.  The  antero-posterior  group 
comprises  four  curves,  named  cervical,  thoracic,  lumbar,  and 
pelvic.  The  cervical  and  lumbar  curves  have  their  convexities 
directed  forwards,  and  the  thoracic  and  pelvic  curves  have  their 
convexities  directed  backwards.  The  lumbar  and  pelvic  curves 
meet  rather  abruptly  and  form  a  projection,  called  the  sacro- 
vertehral  angle,  which  is  estimated  at  117  degrees  in  the  male  and 
130  degrees  in  the  female.  The  curves  impart  springiness-  or 
elasticity  to  the  column,  and  so  guard  it  against  shock.  The 
thoracic  and  pelvic  curves  are  associated  with  the  thoracic  and 
pelvic  cavities,  the  capacity  of  which  they  serve  to  increase.  They 
appear  in  early  foetal  life,  and  are  known  as  primary  curves.  The 
cervical  and  lumbar  curves  do  not  appear  until  after  birth,  and 
are  known  as  secondary  or  compensatory  curves.  The  primary 
curves  are  brought  about  by  the  greater  depth  posteriorly  of  the 
thoracic  and  sacral  bodies,  whilst  the  compensatory  curves  are 
largely  due  to  the  intervertebral  discs,  though  in  the  lumbar  region 
the  greater  depth  of  the  bodies  anteriorly,  especially  in  the  fifth 
lumbar,  must  also  be  taken  into  account. 

The  lateral  group  comprises  two  curves.  One  is  situated  in  the 
upper  thoracic  region,  with  its  convexity  directed  towards  the  right 
side  in  right-handed  persons,  and  it  is  to  be  regarded  as  due  to  the 
greater  use  made  of  the  right  arm.  To  compensate  for  this  curve 
there  is  another  slight  curve  in  the  upper  lumbar  region,  with  the 
convexity  to  the  left. 

When  viewed  anteriorly,  the  column  presents  the  bodies,  which 
form  the  pyramids  already  described.  When  viewed  laterally, 
it  presents  the  sides  of  the  bodies,  pedicles,  intervertebral  foramina, 
and  articular  and  transverse  processes.     The  intervertebral  foramina 


THE  BONES  OE  THE  TRUNK 


39 


StC. 


I  ist  Lumliar 


Sacrum 


Cuccyx 


I-iG.  28  — The  Vertebkal  Column 
(Lateral  View). 

(The  Blue  Markings  represent  the 
Facets  on  the  Bodies  and  Trans- 
verse I'rocesses. ) 


istT. 


I  si  L. 


ist  Co. 


Fig.  29. — The  Vertebral  Column 
(Posterior  View). 


40  A   MANUAL  OF  ANATOMY 

are  formed  by  the  apposition  of  the  superior  and  inferior  vertebral 
notches  of  contiguous  pedicles.  They  lead  outwards  from  the 
spinal  canal,  and  each  transmits  a  spinal  nerve.  They  increase 
in  size  from  above  downwards  until  the  sacrum  is  reached,  in  which, 
though  hidden  at  either  side  of  the  central  mass,  they  diminish 
in  size  from  above  downwards.  In  this  region  each  intervertebral 
foramen  opens  on  the  front  and  back  of  the  sacrum  by  means  of  an 
anterior  and  posterior  sacral  foramen,  the  arrangement  thus  formed 
resembling  a  capital  V,  the  apex  being  at  an  intervertebral  foramen. 
On  the  lateral  aspect  of  the  thoracic  portion  of  the  column  are 
seen  the  costo- capitular  facets,  which  are  twelve  in  number.  The 
first  is  situated  on  the  upper  part  of  the  side  of  the  first  thoracic 
body.  The  second  to  the  tenth  inclusive  are  situated  on  the 
contiguous  margins  of  the  bodies  of  the  vertebrae,  each  being 
formed  by  the  small  inferior  demi- facet  of  the  upper  body  and  the 
large  superior  demi-facet  of  the  lower.  The  eleventh  and  twelfth 
are  situated  on  the  sides  of  the  corresponding  pedicles.  The  tenth 
facet  may  belong  entirely  to  the  tenth  thoracic  vertebra.  The 
thoracic  transverse  processes,  except  the  eleventh  and  twelfth  (and 
sometimes  the  tenth),  are  faceted  in  front  at  their  extremities 
for  the  tubercles  of  the  ribs. 

When  the  column  is  viewed  from  behind  the  following  parts 
are  seen  :  the  spinous  processes  ;  the  laminae  ;  the  articular  pro- 
cesses ;  the  backs  of  the  transverse  processes ;  and  the  dorsum  of 
the  sacrum  and  coccyx.  The  cervical  spines,  except  the  sixth 
and  seventh,  are  short,  so  as  not  to  interfere  with  backward 
flexion  or  over-extension  of  the  neck.  The  middle  thoracic  spines 
are  imbricated,  and  the  lumbar  spines  stand  out  horizontally. 
On  either  side  of  the  spines  there  is  the  vertical  groove,  which  is 
occupied  by  the  deep  muscles  of  the  back,  the  deepest  being  the 
multifidus  spinee.  This  groove  is  bounded  internally  by  the  spines, 
and  externally  by  the  transverse  processes  in  the  cervical  and 
thoracic  regions,  and  by  the  mammillary  tubercles  in  the  lumbar 
region.  The  floor  is  formed  by  the  laminae,  and  its  continuation 
over  the  back  of  the  sacrum  is  known  as  the  sacral  groove. 

The  spinal  canal  is  situated  behind  the  bodies  of  the  vertebrae,  and 
is  formed  by  the  neural  foramina  of  all  the  vertebrae  except  the 
fifth  sacral  and  four  coccygeal.  It  commences  at  the  level  of  the 
atlas,  and  it  terminates  as  a  rule  upon  the  back  of  the  body  of  the 
fifth  sacral  vertebra.  It  adapts  itself  to  the  various  curves  of  the 
column,  and  is  large  and  triangular  in  the  cervical  and  lumbar 
regions,  small  and  circular  in  the  thoracic,  and  triangular  in  the 
upper  part,  but  crescentic  in  the  lower  part,  of  the  sacral  region. 
It  contains  the  spinal  cord  and  its  membranes  as  low  as  about  the 
level  of  the  disc  between  the  first  and  second  lumbar  bodies,  and  a 
copious  plexus  of  vessels.  Below  the  level  just  mentioned  it  con- 
tains the  filum  terminale  of  the  spinal  cord  and  the  leash  of  nerves 
known  as  the  cauda  equina,  with  their  coverings.  The  dura- 
matral  covering  or  theca  ceases  by  taking  attachment  to  the  back 


THE  BONES  OF  THE  TRUNK  41 

of  the  second  sacral  body,  and  the  filum  terminale  passes  on  to 
be  attached  to  the  back  of  the  fifth  sacral  or  first  coccygeal 
vertebra. 

B.  The  Ribs. 

The  ribs  (costse)  are  twelve  in  number  at  either  side,  and  are 
arranged  in  two  groups,  true  or  sternal,  and  false  or  asternal.  The 
true  ribs  are  those  which  articulate  directly  with  the  sternum  by  their 
costal  cartilages,  and  they  represent  as  a  rule  the  first  seven  at  either 
side.  The  false  ribs  are  those  which  have  no  direct  articulation  by 
their  costal  cartilages  with  the  sternum,  and  they  represent,  as  a 
rule,  the  last  live  at  either  side.  The  last  two  false  ribs,  eleventh 
and  twelfth,  are  called  the  free  or  floating  ribs,  because  their  costal 
cartilages  stand  quite  clear  of  each  other  and  of  the  tenth.  The 
ribs  are  elastic,  and  increase  in  length  from  the  first  to  the  seventh, 
whence  they  decrease  to  the  twelfth.  The  first  is  the  broadest, 
and  the  twelfth  the  narrowest.  Their  direction  is  at  first  down- 
wards, outwards,  and  slightly  backwards,  then  downwards  and 
forwards,  and  finally  inwards.  The  upper  ribs  are  not  so  oblique 
as  those  lower  down,  the  most  oblique  being  the  ninth.  With  the 
exception  of  the  first  rib,  the  surfaces  of  the  others  are  vertically 
disposed  posteriorly,  but  in  front  they  are  sloped  downwards  and 
forwards,  and  this  circumstance  renders  most  of  them  twisted. 

A  Typical  Rib. — A  typical  rib  presents  for  consideration  a  head, 
neck,  tubercle,  shaft,  and  sternal  extremity. 

The  head  (capitulum)  forms  the  posterior  or  vertebral  extremity, 
and  is  slightly  expanded.  It  presents  an  irregularly  fiat  surface 
and  an  anterior  margin.  The  surface  is  marked  by  two  oblique 
facets,  upper  and  lower,  which  are  separated  by  a  horizontal  ridge. 
The  lower  or  primary  facet  is  the  larger  of  the  two,  and  articulates 
with  the  large  upper  or  primary  demi-facet  of  the  lower  of  the  two 
thoracic  bodies  with  which  the  head  is  connected.  The  upper 
facet  articulates  with  the  small  lower  demi-facet  on  the  side  of  the 
upper  thoracic  body,  and  the  intervening  ridge  gives  attachment 
to  the  interarticular  ligament.  The  anterior  margin  gives  attach- 
ment to  the  anterior  costo-central  ligament. 

The  neck  is  about  i  inch  long,  and  is  compressed  from  before 
backwards.  Its  anterior  surface  is  smooth  and  covered  by  the 
costal  pleura.  Its  posterior  surface,  which  is  rough,  faces  the  anterior 
surface  of  the  lower  thoracic  transverse  process,  or  that  with  which 
its  tubercle  articulates,  and  it  gives  attachment  to  the  middle 
costo-transverse  or  interosseous  ligament.  Its  superior  border 
forms  a  sharp  lip,  called  the  crest,  which  gives  attachment  to  the 
superior  costo-transverse  ligament.  Its  inferior  border  may  show 
traces  of  the  subcostal  groove. 

The  tubercle  is  situated  on  the  external  surface  of  the  rib  at  the 
outer  extremity  of  the  neck,  and  presents  two  divisions,  articular 
and   non-articular.     The   articular   division,    inferior   and   slightly 


42 


A  MANUAL  OF  ANATOMY 


internal  in  position,  presents  a  somewhat  oval  facet  for  articulation 
with  that  on  the  front  of  the  extremity  of  the  lower  thoracic  trans- 
verse process.     The  non- articular  division,   superior   and  slightly 


Neck 


Articular  Part  of  Tubercle 
Ligamentous  Part  of  Tubercle 


External- 
Intercostal 


Internal  - 
Intercostal 


Fig.   30. — The  Sixth  Left  Rib  (Internal  View). 

external  in  position,  gives  attachment  to  the  posterior  costo-trans- 
verse  ligament. 
The  shaft  is  curved  and  twisted.     It  presents  two  surfaces  and 


THE  BONES  OF  THE  TRUNK  43 

two  borders.  The  external  surface  is  convex,  and  its  plane  is  vertical 
behind,  but  oblique  in  front,  being  here  sloped  downwards  and 
forwards.  Opposite  the  greatest  bend  of  the  rib  it  presents  an 
oblique  ridge,  directed  downwards  and  outwards,  called  the  angle, 
for  a  tendinous  slip  of  the  erector  spinpe.  The  surface  between 
the  tubercle  and  the  angle  gives  attachment  to  the  longissimus 
dorsi.  Near  to  the  anterior  extremity  (about  2  inches  from  it)  the 
external  surface  presents  another  oblique  ridge  directed  downwards 
and  outwards,  known  as  the  anterior  angle,  where  the  rib  describes 
a  slight  curve.  The  internal  surface,  which  is  concave,  is  covered 
by  the  costal  pleura.  At  its  lower  part  it  presents  the  subcostal 
groove,  to  be  presently  described.  The  superior  border  is  thick 
and  round  behind,  but  thin  and  sharp  in  front.  Its  outer  Hp  gives 
attachment  to  an  external  intercostal  muscle,  and  its  inner  lip  to 
an  internal  intercostal,  a  collateral  intercostal  artery  lying  between 
the  two  muscles.  The  inferior  border  is  for  the  most  part  sharp  and 
wiry.  Immediately  within  and  above  it  there  is  the  subcostal 
groove,  which  commences  behind  at  the  tubercle  and  disappears 
over  the  anterior  fifth.  Posteriorly  the  groove  belongs  to  the 
inferior  border.  Its  upper  lip  is  rounded  and  gives  attachment  to 
an  internal  intercostal  muscle,  whilst  the  lower  lip  gives  attach- 
ment to  an  external  intercostal.  The  nutrient  foramen  is  situated 
in  the  subcostal  groove  a  little  anterior  to  the  centre  of  the  bone, 
and  the  canal  to  which  it  leads  is  directed  towards  the  head.  It 
gives  passage  to  a  branch  of  the  intercostal  artery  which  lies  in 
the  groove.  The  contents  of  the  groove  from  above  downwards 
are  an  intercostal  vein,  artery,  and  nerve. 

The  anterior  or  sternal  extremity  presents  an  oval  pit,  which  is 
almost  vertical  in  direction,  for  the  costal  cartilage. 

The  Peculiar  Ribs. — These  are  the  first,  second,  tenth,  eleventh, 
and  twelfth. 

The  First  Rib. — This  is  the  shortest,  broadest,  and  flattest  of 
all  the  ribs,  and  its  curve  is  very  distinct,  but  there  is  no  twist. 
The  head  is  small,  and  presents  a  nearly  circular  facet  for  articula- 
tion with  the  entire  facet  on  the  body  of  the  first  thoracic  vertebra. 
The  neck  is  narrow,  and  compressed  from  above  downwards.  The 
tubercle,  which  is  large,  is  situated  on  the  external  border  at  the 
junction  of  the  neck  with  the  shaft.  Being  placed  opposite  the 
greatest  bend  of  the  bone,  it  takes  the  place  of  the  angle,  and  pre- 
sents the  usual  articular  and  non-articular  portions,  the  former 
being  for  the  first  thoracic  transverse  process. 

The  shaft  is  broad  and  compressed  from  above  downwards,  its 
surfaces  being  superior  and  inferior,  whilst  the  borders  are  internal 
and  external.  The  superior  surface  close  to  the  anterior  extremity 
gives  attachment  to  the  tendon  of  the  subclavius  and  the 
costo-coracoid  ligament.  Farther  back  there  are  two  oblique 
grooves,  separated  to  a  limited  extent  by  a  tubercle  or  spine 
for  the  scalenus  anticus.  The  anterior  groove  is  shallow,  and 
lodges    the    subclavian   vein,  whilst   the   posterior  deeper  groove 


44 


A  MANUAL  OF  ANATOMY 


is  occupied  by  the  third  part  of  the  subclavian  artery  and  the 
trunks  of  the  brachial  plexus  of  nerves.  Behind  the  posterior 
groove,  and  extending  as  far  back  as  the  tubercle,  there  is  a 
rough  impression  for  the  insertion  of  the  scalenus  medius.  The 
inferior  surface  is  flat  and  covered  by  the  costal  pleura.  Near  the 
external  border  it  gives  attachment  to  the  internal  intercostal 
muscle  of  the  first  space.  The  internal  border,  which  is  thin  and 
concave,  gives  attachment  to  Sibson's  fascia.     Fully  i  inch  from 


Groove  for  Subclavian  Artery. 
Scalenus  Anticus. 
Serratus  Magnus. 


Groove  for  Subclavian.  _ 
Vein 


Sternal  Extremity 
Subclavius 


Scalenus  Posticus 


Serratus 
Magnus 


Fig.  31. — The  First  and  Second  Ribs  of  the  Left  Side 
(Superior  View). 

the  anterior  extremity  this  border  presents  a  projection,  called  the 
scalene  tubercle  or  spine  {tubercle  of  Lisfranc),  for  the  insertion  of 
the  scalenus  anticus.  It  encroaches  slightly  on  the  adjacent  part 
of  the  superior  surface,  and  is  inclined  backwards.  The  external 
border  is  convex.  It  gives  attachment  to  the  external  inter- 
costal muscle  of  the  first  space,  and  a  portion  of  the  first  serration 
of  the  serratus  magnus  at  a  point  opposite  the  groove  for  the  sub- 
clavian artery,  where  the  external  border  is  often  prominent.     The 


THE  BONES  OF  THE  TRUNK 


45 


anterior  extremity  presents  the  usual  oval  pit  for  the  first  costal 
cartilage,  its  direction  being  horizontal  from  before  backwards. 
The  tirst  rib  has  no  subcostal  groove. 

The  Second  Rib. — The  surfaces  of  the  shaft  of  this  rib  occupy  a 
transitional  plane  between  that  of  the  first  and  those  of  the  suc- 
ceeding ribs.  It  is  practically  destitute  of  a  twist.  The  neck  is 
compressed  from  above  downwar  •  s, 
and  from  before  backwards.  The 
distinctive  character  of  the  bone  is 
the  presence  on  its  supero-external 
surface,  near  the  centre,  of  a  rough 
oval  eminence  for  a  portion  of  the 
first  and  the  second  slips  of  the 
serratus  magnus.  Behind  this  im- 
pression the  surface  gives  insertion 
to  the  scalenus  posticus. 

The  Tenth  Rib. — This  bone  may 
or  may  not  be  peculiar.  If  the 
body  of  the  ninth  thoracic  vertebra 
has  a  lower  demi-facet.  there  is 
nothing  peculiar  about  the  head  of 
the  tenth  rib.  If,  however,  the 
lower  demi-facet  is  wanting  on 
the  ninth  thoracic  body,  the  head 
of  the  tenth  rib  has  only  one  facet 
for  that  on  the  body  and  pedicle 
of  the  tenth  thoracic  vertebra.  The 
tubercle  has  ususilly  an  articular 
facet  for  the  tenth  thoracic  trans- 
verse process,  but  this  may  be 
awanting.  The  angle  and  subcostal 
groove  are  well  marked. 

The  Eleventh  Rib.— The  head  of 
this  rib  has  one  facet  for  that  on 
the  pedicle  of  the  eleventh  thoracic 
vertebra.  There  is  a  slight  tubercle, 
destitute  of  an  articular  facet,  a 
faint  angle,  and  an  equally  faint 
subcostal  groove.  The  anterior  ex- 
tremity is  pointed,  and  only  tipped 
with  a  costal  cartilage,  which  is  free. 

The  Twelfth  Rib.— This  is  a  very  short  bone.  Its  head  has  one 
facet  for  that  on  the  pedicle  of  the  twelfth  thoracic  vertebra.  The 
tubercle,  angle,  and  subcostal  groove  are  awanting  The  shaft  is 
very  narrow,  and  terminates  anteriorly  in  a  pointed  extremity, 
which  is  merely  tipped  with  a  free  costal  cartihige.  The  lower 
border  of  the  shaft  has  a  rough,  sharp  outline,  and  gives  attachment 
lo  a  portion  of  the  quadratus  lumborum  muscle,  whilst  the  upper 
border,  especially  towards  the  back  part,  is  smc^oth  and  round. 


Fig.  32.  —  The  Eleventh  and 
Twelfth  Ribs  of  the  Left 
Side  (Inferior  View). 


46 


A   MANUAL  OF  ANATOMY 


\  Appear  about  the  i6th  Year, 
/and  join  about  the  25th  Year 


The  ribs  are  supplied  with  blood  by  branches  of  the  intercostal 
arteries. 

Structure.- — A  rib  is  composed  of  loose  cancellated  tissue  sur- 
rounded by  compact  bone. 

Varieties. —  ( i )  The  number  may  be  increased  to  thirteen  on  one  or  both  sid  es. 
and  the  supernumerary  rib  may  be  cervical  or  lumbar.  If  cervical,  it  is 
developed  in  connection  with  the  costal  process  of  the  seventh  cervical  vertebra. 
It  may  join  the  shaft  of  the  iirst  thoracic  rib,  or  it  may  reach  the  sternum.  If 
lumbar,  it  is  developed  in  connection  with  the  costal  element  of  the  first  lumbar 
vertebra,  is  usually  very  short,  and  doe?:  not  articulate  with  the  body  of  that 

vertebra.  (2)  In  rare  cases  the 
number  may  be  decreased  by  one, 
at  the  expense  of  the  twelfth  rib. 
(3)  The  ribs  are  subject  to  variety 
in  form  as  follows :  [a)  the  verte- 
bral end  of  the  first  thoracic  rib 
may  be  joined  by  a  cervical  rib,  or 
by  the  vertebral  end  of  the  second 
rib,  in  which  cases  the  variety 
known  as  bicipital  rib  occurs ; 
(6)  the  anterior  extremity  of  a  rib 
may  be  bifurcated ;  (c)  adjacent 
ribs  may  be  connected  by  small 
plates  of  bone. 

Ossification. — An  ordinary  rib 
has  one  primary  centre  and  three 
secondary  centres.  The  primary 
centre  for  the  shaft  appears 
about  the  sixth  week  near  the 
angle.  Ossification  proceeds  so 
rapidly  along  the  shaft  that  by 
the  fourth  month  the  shaft  is 
completely  bssified.  The  second- 
ary centres  appear  about  the  six- 
teenth year.  One  gives  rise  to  the  head,  and  of  the  other  two  one  is  for  the 
rough  part  of  the  tubercle  and  the  other  for  its  articular  part.  The  head  and 
two  parts  of  the  tubercle  join  the  shaft  about  the  twenty-fifth  year.  The  two 
secondary  tubercular  centres  are  absent  in  the  eleventh  and  twelfth  ribs. 


\ Appears  about  the  8th  Week 

(intra-uterine) 


Fig.  33. — Ossification  of  a  Rib. 


The  Costal  Cartilages. 

The  costal  cartilages,  which  are  composed  of  hyaline  cartilage, 
are  twelve  in  number  on  either  side.  The  outer  extremity  of  each 
is  received  into  the  oval  pit  on  the  anterior  extremity  of  a  rib, 
and  is  there  maintained  in  position  by  the  continuity  which  takes 
place  between  the  periosteum  of  the  rib  and  the  perichondrium  of 
the  cartilage.  The  inner  extremities  of  the  true  ribs  articulate 
with  the  side  of  the  sternum  by  means  of  synovial  joints,  except 
in  the  case  of  the  first,  which  is  directly  united  to  the  presternum 
without  the  intervention  of  a  synovial  membrane.  The  eighth 
as  a  rule,  ninth,  and  tenth  do  not  reach  the  sternum,  and  they 
articulate  with  each  other  by  synovial  joints,  each  cartilage  being 
widened  at  the  place  of  articulation,  where  it  sends  downwards  a 
process  to  the  upper  border  of  the  cartilage  below.  In  this  way 
interchondral  joints  are  formed  between  these  cartilages,  as  well 


THE  BONES  OF  THE  TRUNK         ■  47 

as  between  the  eighth,  seventh,  sixth,  and  sometimes  the  fifth. 
The  eleventh  and  twelfth  cartilages  are  mere  nodules  tipping  the 
corresponding  ribs,  and  they  have  no  articulation  with  each  other, 
nor  has  the  eleventh  with  the  tenth.  The  cartilages  increase  in 
length  from  the  first  to  the  seventh,  beyond  which  they  gradually 
diminish  to  the  twelfth.  They  diminish  in  breadth  from  above 
downwards.  The  direction  of  the  first  cartilage  is  inwards  and 
downwards,  and  that  of  the  second  horizontally  inwards,  whilst 
the  succeeding  ones,  except  the  eleventh  and  twelfth,  incline  more 
and  more  upwards  as  they  pass  inwards.  Prior  to  middle  life  the 
first  costal  cartilage  undergoes  superficial  ossification  underneath 
the  perichondrium,  and  so  a  thin  shell  of  bone  is  formed  around 
it.  In  advanced  life  this  condition  may  be  met  with  in  the  other 
costal  cartilages  to  a  certain  extent. 

C.  The  Sternum. 

The  sternum  or  breast-bone  is  situated  in  the  middle  line  of 
the  anterior  wall  of  the  thorax,  where  it  articulates  on  either  side 
with  the  first  seven  costal  cartilages,  and  superiorly  with  the 
clavicle.  It  occupies  an  oblique  plane,  which  is  directed  downwards 
and  forwards,  forming  an  angle  with  the  vertical  of  about  20  degrees. 
It  is  compressed  from  before  backwards,  of  unequal  width  at 
different  parts,  and  more  or  less  curved  from  above  downwards, 
the  convexity  being  directed  forwards,  and  being  very  pronounced 
in  the  condition  known  as  '  pigeori-breast.'  The  bone  is  originally 
composed  of  six  segments,  called  sternebrae.  The  first  sternebra 
forms  the  manubrium  ('  handle  ')  or  presternum.  The  succeeding 
four  sternebrce  form  the  body,  gladiolus,  or  meso-sternum,  and  the 
sixth  sternebra  forms  the  ensiform  or  xiphoid  process  [xiphi- 
sternum),  otherwise  known  as  the  metasternum. 

The  presternum  is  irregularly  four-sided,  and  broader  above 
than  below.  It  presents  two  surfaces  and  four  borders.  The 
anterior  surface  is  convex  from  side  to  side,  and  concave  from  above 
downwards.  It  gives  origin  at  either  side  to  a  portion  of  the 
pectoralis  major,  and  at  its  upper  and  outer  part  to  the  sternal 
head  of  the  sterno-cleido  mastoid.  Between  the  latter  point  and 
the  clavicular  depression  on  the  upper  border  it  gives  attachment  to 
the  anterior  sterno-clavicular  ligament.  The  posterior  surface  is 
concave.  At  its  upper  and  outer  part  it  gives  origin  to  portions 
of  the  sterno-hyoid  and  sterno-thyroid,  the  former  being  the  higher 
of  the  two,  and  close  to  the  clavicular  depression  it  gives  attach- 
ment to  the  posterior  sterno-clavicular  ligament.  The  superior 
border  over  its  middle  portion  presents  the  interclavicular  or  semi- 
lunar notch,  which  gives  attachment  to  fibres  of  the  interclavicular 
ligament.  At  either  side  of  this  there  is  a  large,  oval,  concavo- 
convex  articular  surface  for  the  clavicle,  which  is  directed  upwards, 
outwards,  and  slightly  backwards,  an  interarticular  fibro-cartilage 
intervening  between  the  bones.      Close  to  the  inner  end  of  each 


A  MANUAL  OF  ANATOMY 


clavicular  depression  there  may  be  found,  on  the  anterior  aspect, 
an  ossicle,  known  as  the  episternal  hone.  The  inferior  border,  which 
is  short  and  straight,  articulates  with  the  mesosternum,  a  disc  of 
fibro- cartilage  intervening.      In  this  situation  there  is  a  transverse 


Interclavicular  Notch 


Stemo-cleido-mastoid 


Pectoralis  Major 


Rectus  Abdominis 


Clavicular  Surface 


.  _  For  I  St  Costal  Cartilage 


Fig.  34. — The  Sternum  (Anterior  Surface). 

elevation,  called  the  sternal  angle,  which  serves  as  a  guide  to  the 
second  rib  at  either  side.  Each  lateral  border  slopes  downwards 
and  inwards.  The  upper  part  presents  a  triangular  depression  for 
the  first  costal  cartilage,  and  close  to  the  lower  part  a  demi-facet 
for  a  portion  of  the  second  costal  cartilage. 


THE  BONES  OF  THE   TRUNK 


49 


The  mesosternum  presents  two  surfaces  and  four  borders.  The 
anterior  surface  is  marked  by  three  transverse  hues,  which  indicate 
the  places  of  junction  of  the  original  four  sternebrae.  At  either 
side  it  gives  origin  to  a  large  portion  of  the  pectoralis  major.  The 
posterior  surface  presents  traces 
of  the  highest   transverse   line,  .  /^~^ 

but  the  lower  two  have  usually  ^^''^-"  ^^ —rr-  J 
become  effaced.  Adjacent  to 
each  lateral  border  it  gives  origin 
to  a  portion  of  the  triangularis 
sterni,  as  high  as  the  level  of 
the  third  costal  facet.  Each 
lateral  border  presents  a  series  of 
costal  facets,  disposed  as  follows : 
close  to  the  upper  extremity 
there  is  a  demi- facet  for  a 
portion  of  the  second  costal 
cartilage  ;  opposite  each  of  the 
three  transverse  lines  there  is 
an  entire  facet  for  the  third, 
fourth,  and  fifth  costal  carti- 
lages ;  and  on  the  side  of  the 
fourth  segment  of  the  body 
there  are  usually  one  entire  facet 
and  one  demi-facet  lying  close 
together,  the  former  being  for 
the  sixth  costal  cartilage,  and 
the  latter  for  a  portion  of  the 
seventh.  Altogether  there  are 
usually  four  entire  facets  and 
two  demi-facets  on  each  lateral 
border,  the  demi  -  facets  being 
situated  one  at  either  extremity. 
Sometimes,  however,  the  inferior 
demi  -  facet  is  replaced  by  an 
entire  facet  for  the  whole  of  the 
seventh  costal  cartilage.  Each 
of  the  upper  three  entire  facets 
is  made  up  of  the  contiguous 
demi-facets  of  two  adjacent 
sternebrse,  as  in  the  bodies  of 
most  of  the  thoracic  vertebrae. 
The  superior  border  of  the  meso- 
sternum articulates,  as  stated, 
with  the  presternum.  The  infer ior  border,  which  is  very  narrow, 
articulates  with  the  metasternum,  an  intersternebral  disc  inter- 
vening until  about  the  fortieth  year,  when  osseous  union  usually 
takes  place. 

The  metasternum  is  subject  to  much  variety  as  regards  condition, 

4 


Fig.  35. — The  Sternum 
(Lateral  View). 


50  A   MANUAL  OF  ANATOMY 

direction,  and  form.  It  may  be  entirely  osseous,  or  osseous  above 
and  cartilaginous  below.  Its  typical  direction  is  downwards 
between  the  seventh  pair  of  costal  cartilages,  but  it  may  have  an 
inclination  forwards,  backwards,  or  even  to  one  side.  It  is  narrow 
from  side  to  side,  and  compressed  from  before  backwards.  It 
may  terminate  in  a  thin  transverse  border,  in  a  sharp  point,  or  in 
a  bifurcated  extremity.  The  anterior  surface  lies  at  the  bottom 
of  the  infrasternal  depression.  The  posterior  surface  gives  origin 
at  either  side  to  a  portion  of  the  triangularis  sterni,  and  interiorly 
it  gives  origin  to  a  portion  of  the  diaphragm,  usually  in  the  form  of 
two  fleshy  slips.  The  superior  border  articulates  with  the  meso- 
sternum,  and  the  inferior  border  gives  attachment  to  the  linea  alba. 
Each  lateral  border  usually  presents  superiorly  a  demi-facet  for  a 
portion  of  the  seventh  costal  cartilage,  but  this  may  be  transferred 
to  the  fourth  segment  of  the  mesosternum.  In  rare  cases  there  may 
be  an  entire  facet  for  the  eighth  costal  cartilage,  this  being  constant 
in  early  life.  The  lateral  border  gives  insertion  at  either  side  to 
some  of  the  fibres  of  the  internal  oblique  aponeurosis,  and  occasion- 
ally, at  its  upper  part,  to  a  portion  of  the  rectus  abdominis. 

The  sternum  derives  its  blood-supply  from  branches  of  the 
internal  mammary  artery. 

Articulations. — With  the  clavicle  and  first  seven  costal  cartilages, 
at  either  side. 

Structure. — The  sternum  is  composed  of  cancellated  tissue  covered 
by  a  thin  layer  of  compact  bone. 

Varieties. — (i)  The  sternum  is  sometimes  characterized  by  its  shortness, 
breadth,  and  great  depression  in  its  lower  part.  This  condition  is  liable  to  be 
met  with  in  cobblers.  (2)  A  sternal  foramen  may  be  present  in  the  mesosternum, 
usually  in  the  third  or  fourth  segment.  (3)  A  sternal  foramen  may  be  present 
in  the  metasternum.  (4)  In  very  rare  cases  the  sternum  may  be  intersected 
from  end  to  end  by  a  sternal  fissure,  in  which  cases  the  heart  and  pericardium 
are  left  uncovered  (ectopia  cordis).  (5)  The  costal  cartilages  may  articulate 
with  the  sternum  asymmetrically. 

The  Sternum  of  the  Female. — The  bone  is  usually  shorter  than 
in  the  male,  the  shortness  affecting  the  mesosternum. 

Ossification. — The  sternum  ossifies  in  cartilage  from  a  variable  number  of 
centres.  There  is  usually  one  centre  for  the  presternum,  which  appears  in 
the  sixth  month  of  intra-uterine  life.     Sometimes  there  are  two,  placed  one 

above  the  other,  and  there  miay  be  as  many  as  six,  placed  thus  ■  •   •      The 

first  segment  of  the  mesosternum  usually  ossifies  from  one  centre,  appearing 
in  the  seventh  month,  though  there  may  be  two,  disposed  laterally.  The 
second,  third,  and  fourth  segments  of  the  mesosternum  usually  ossify  from 
two  centres  each,  which  are  disposed  laterally  and  remain  separate  for  some 
time,  but  subsequently  unite  as  a  rule.  There  may,  however,  be  only  one 
mesial  centre  for  each  of  these  segments.  In  the  second  segment  they  appear 
in  the  eighth  month,  in  the  third  just  before  birth,  and  in  the  fourth  during 
the  first  year.  The  metasternum  ossifies  from  one  centre,  which  appears  in 
its  upper  part  from  the  third  to  the  sixth  year,  though  it  may  be  delayed  to  a 
later  period.  The  lower  three  segments  of  the  mesosternum  unite  in  order 
from  below  upwards,  the  union  commencing  about  puberty  and  being  com- 
pleted shortly  afterwards.  The  first  segment  of  the  mesosternum  joins  the 
remainder  about  twenty-five.     The  metasternum  unites  with  the  mesosternum 


THE  BONES  OF  THE  TRUNK 


SI 


about    forty,    but    the    presternum    usually   remains    permanently    separate 
unless  in  advanced  life,  when  it  may  become  ankylosed  to  the  mesosternum. 
The     sternal  cartilage  from  wliich  the  bone  is  developed  consists   origin- 
ally of  two  elongated  strips,  each  of  which  bears  the  cartilages  of  nine  ribs. 
The  strips  are  separated  for  some  time  by  a  median  fissure,  but  fusion  sub- 
^sequently    takes   place,    and    so   a    single   sternal  cartilage  is   formed.     The 
'eighth  costal  cartilage  usually  loses  its  connection  with  the  sternum,  though 
it   may  articulate   permanently   with    the   metasternum.     The   ninth   costal 
cartilage  at  either  side  is  regarded  as  dividing  into  two  parts,  one  of  which 

Episternal  Bone 


...Appears  in  the  6th  Month 
(intra-uterine) 


|g( [ 7th  Month 

__,  8th  Month 

_  9th  Month 

ist  Year 

3rd  to  6th  Year 


Fig. 


Ossification  of  the 
Sternum. 


VilU 

Fig.  37. — Development  of 

THE  Sternum 

(Modified  from  Ruga). 

remains  connected  with  the  sternal  cartilage  and  forms  with  its  fellow  the 
metasternum,  whilst  the  other  acquires  a  connection  with  the  eighth  costal 
cartilage.  If  the  parts  of  the  ninth  costal  cartilages,  which  remain  connected 
with  the  sternal  cartilage,  do  not  unite  with  each  other  over  their  whole 
extent,  a  bifurcated  metasternum  is  the  result.  They  usually,  however,  unite 
whoUv,  or  sometimes  in  such  a  manner  as  to  leave  a  foramen  at  the  centre. 
A  sternal  fissure  is  due  to  the  permanent  separation  of  the  two  original  car- 
tilaginous strips,  which,  as  a  rule,  unite  to  form  the  sternal  cartilage.  A 
sternal  foramen  in  the  second,  third,  or  fourth  segment  of  the  mesosternum 
is  due  to  ossification  from  two  collateral  centres  failing  to  meet  at  the  median 
line. 

Sometimes  two  ossicles,  called  the  episternal  bones,  are  met  with  at  either 
side  of  the  interclavicular  notch  of  the  sternum.  These  are  developed  in 
connection  with  the  suprasternal  ligaments,  which  extend  between  the  inner 
end  of  each  clavicle  and  the  upper  end  of  the  sternum.  These  ligaments 
represent  the  inner  extremities  of  the  precoracoid  cartilaginous  bars. 


The  Thorax  as  a  Whole. 

The  thorax  constitutes  an  osseous  and  cartilaginous  cage  which 
lodges  the  heart  and  lungs,  along  with  important  bloodvessels  and 
nerves,  as  well  as  the  trachea  and  (jesophagus.  It  is  bounded 
anteriorly  by  the  sternum,  with  the  costal  cartilages  and  anterior 
extremities  of  the  first  eight  or  nine  ribs  ;  posteriorly  by  the  bodies 
of  the  thoracic  vertebrae  and  the  vertebral  extremities  of  the  ribs 

4—2 


52 


A  MANUAL  OF  ANATOMY 


from  the  heads  to  the  angles  ;  and  laterally  by  the  ribs  beyond  their 
angles.  It  is  conical,  the  truncated  apex  being  directed  upwards, 
and  it  is  somewhat  flattened  from  before  backwards. 

The  superior  aperture  is  bounded  in  front  by  the  upper  border 
of  the  presternum  and  the  first  costal  cartilages,  on  either  side  by. 


The  Thorax  (Anterior  View). 


the  first  rib,  and  behind  by  the  body  of  the  first  thoracic  vertebra. 
Its  transverse  measurement  exceeds  the  antero-posterior,  and  it 
is  reniform,  due  to  the  forward  projection  of  the  first  thoracic 
body.  Its  plane  is  obhque,  being  sloped  downwards  and  forwards, 
so  that  the  upper  border  of  the  presternum  is  on  a  level  with  the 
disc  between  the  second  and  third  thoracic  bodies.     The  superior 


THE  BOXES  OF  THE  TRUNK  53 

aperture  transmits  the  following  structures:  the  apical  parts  of 
the  lungs  and  pleurae,  the  trachea  and  oesophagus,  the  pneumo- 
gastric,  sympathetic,  and  phrenic  nerves,  the  terminal  part  of  the 
innominate  artery,  the  left  common  carotid  and  left  subclavian 
arteries,  and  the  right  and  left  innominatii  veins.  In  early  life  it 
also  transmits  the  thymus  body. 

The  inferior  aperture  is  of  large  size,  and  is  bounded  posteriorly 
b}'  the  twelfth  thoracic  body,  laterally  by  the  twelfth  rib  on  either 
side,  and  anteriorly  b\'  a  line,  on  either  side,  connecting  the  costal 
cartilages  from  the  twelfth  to  the  seventh  inclusive.  These  two 
lines  constitute  the  subcostal  angle,  within  which  the  metasternum 
is  situated.  The  inferior  aperture  is  occupied  b}'  the  diaphragm, 
which  presents  certain  openings  for  the  passage  of  important 
structures. 

The  cavity,  on  either  side  of  the  thoracic  bodies,  presents  an 
elongated  groove,  called  the  pulmonary  groove,  which  lodges  the 
thick  posterior  border  of  a  lung.  The  cavity  has  the  following 
diameters,  nameh',  vertical,  transverse,  and  antero-posterior.  The 
vertical  diameter  extends  from  the  superior  aperture  to  the  inferior. 
The  transverse  diameter  extends  from  the  centre  of  a  given  inter- 
costal space  to  the  centre  of  the  corresponding  space  of  the  opposite 
side.  The  antero-posterior  diameter  extends  from  the  anterior  to 
the  posterior  wall,  and  is  necessarily  of  less  extent  in  the  median  hne 
than  on  either  side,  on  account  of  the  projection  formed  by  the 
thoracic  bodies,  its  increase  on  each  side  being  due  to  the  presence 
of  the  pulmonarv  groove.  The  cavity  is  increased  in  all  these 
diameters  during  inspiration,  and  diminished  during  expiration. 

The  intercostal  spaces  are  eleven  in  number  on  either  side.  They 
increase  in  length  from  the  first  to  the  fifth,  and  are  occupied  for 
the  greater  part  of  their  extent  by  the  external  and  internal  inter- 
costal muscles. 

The  thorax  of  the  female  is  rather  shorter  than  that  of  the  male, 
and  is  not  so  much  flattened  from  before  backwards. 

In  early  life  the  thorax  is  flattened  from  side  to  side,  and  its 
height  is  relatively  less  than  in  the  adult. 


Development  of  the  Vertebral  Column,  Ribs,  and  Sternum. 

'J  he  notochord  or  chorda  dorsalis  is  the  primitive  axis  round  which 
the  vertebral  column  is  develop2d.  It  is  a  cellular,  rod-hke  structure  of 
hypoblastic  origin,  which  lies  below  the  neural  canal,  where  it  is  placed 
between  the  epiblast  of  that  canal  and  the  hypoblast  of  the  visceral  cavity, 
being  connected  with  the  mesoblast  at  either  side.  It  becomes  invested  by 
a  sheath  formed  of  cells  derived  from  the  mesoblast.  This  sheath  is  known 
as  the  skeletogenous  sheath,  and  it  also  invests  the  neural  canal.  This  con- 
stitutes the  first  stage  in  the  development  of  the  vertebral  column,  namely, 
the  membranous  stage. 

'Jhe  mesoblast  on  each  side  of  the  notochord  and  neural  canal  becomes 
broken  up  into  a  number  of  segments,  called  protovertebrae  or  mesoblastic 
;>omites  (body-segments).  It  is  not,  however,  to  be  supposed  that  the  so- 
called  protovertebra:  are  the  precursors  of  the  future  vertebrae.     They  have 


54  A   MANUAL  OF  ANATOMY 

specially  to  do  with  the  development  of  the  voluntary  muscles  from  muscle- 
plates  or  myotomes.  Each  mesoblastic  somite  consists  of  cells  arranged  in 
three  groups.  From  one  of  these  groups  the  sheath  of  the  notochord 
and  that  of  the  neural  canal  are  derived,  which  form  the  membranous 
vertebral  column .  From  another  group  are  formed  the  muscle  -  plates 
or  myotomes,  which  give  rise  to  the  voluntary  muscles.  The  intervals 
between  the  mesoblastic  somites  are  known  as  the  intersegmental  septa, 
and  it  is  on  a  level  with  these  septa  that  the  bodies  of  the  vertebrae  are  devel- 
oped, the  discs  being  opposite  the  somites.  In  the  membranous  stage  of  the 
vertebral  column  the  body  of  the  vertebra  is  represented  by  the  chordal  part  of 
the  skeletogenous  sheath,  and  the  neural  arch  by  the  neural  part  of  that  sheath. 
At  this  stage  the  vertebra  is  composed  of  a  membranous  body  and  a  neural 
bow.  The  lateral  limbs  of  the  bow  are  placed  on  either  side  of  the  neural 
canal,  and  are  continuous  with  each  other  below,  or  on  the  ventral  aspect 
of,  the  membranous  body,  where  they  form  the  hypochordal  part  of  the 
bow. 

The  second  or  cartilaginous  stage  consists  in  the  chondrification  of  the 
membranous  framework  of  the  body  and  neural  arch,  with  the  exception  of 
the  hypochordal  part  of  the  bow,  which  becomes  incorporated  with  an  inter- 
vertebral disc.  The  two  lateral  limbs  of  the  cartilaginous  neural  arch  meet 
on  the  dorsal  aspect  of  the  neural  canal,  and  so  complete  the  arch.  In  the 
atlas  the  hypochordal  part  of  the  neural  bow  becomes  chondrified  also,  and 
when  ossified  forms  the  anterior  arch. 

The  cartilaginous  body  and  neural  arch  now  join,  and  the  stage  of 
ossification  commences,  which  consists  in  the  deposition  of  osseous  centres 
in  the  body  and  neural  arch.  The  osseous  matter  for  the  body  is  first 
deposited  behind  the  notochord,  and  subsequently  extends  around  it.  The 
notochord  thus  becomes  constricted,  and  ultimately  disappears  in  the  region 
of  the  vertebral  bodies.  The  transverse  and  spinous  processes  are  developed 
in  cartilage  which  grows  outwards  into  the  intersegmental  septa.  The  inter- 
vertebral discs  are  developed  from  the  skeletogenous  sheath  of  the  notochord 
in  the  intervals  between  the  vertebral  bodies  opposite  the  mesoblastic  somites. 
The  mesoblastic  tissue  becomes  transformed  into  the  fibro-cartilage  and 
fibrous  tissue  of  the  discs,  and  in  this  situation  the  notochord  forms  the  central 
pulp  of  each  disc. 

The  ribs  are  developed  in  the  septa  between  the  thoracic  mesoblastic 
somites  from  cartilage  formed  in  extensions  of  their  mesoblast.  They  are 
entirely  supported  by  the  neural  arches  of  the  vertebrae.  At  their  ventral 
extremities  the  first  nine  cartilaginous  ribs  of  each  side  form  by  their  junction 
an  elongated  strip,  and  these  two  strips  by  their  subsequent  union  give  rise 
to  the  cartilage  from  which  the  sternum  is  developed. 


II.— THE  BONES  OF  THE  HEAD. 

The  head  or  skull  is  supported  on  the  upper  end  of  the  vertebral 
column,  and  is  divisible  into  the  cranium  and  face.  The  cranium 
or  brain-case  is  composed  of  eight  bones,  namely,  the  occipital, 
two  parietals,  frontal,  two  temporals,  sphenoid,  and  ethmoid. 
The  face,  which  protects  organs  of  special  sense,  such  as  the  eyes, 
the  olfactory  mucous  membrane,  and  the  tongue,  is  composed  of 
the  following  fourteen  bones,  the  majority  of  which  are  arranged 
in  pairs:  the  two  superior  maxillae,  two  malars,  two  nasals,  two 
lachrymals,  two  inferior  turbinates,  two  palate  bones,  the  vomer, 
and  the  inferior  maxiha.  All  the  bones  of  the  skull,  except  the 
inferior  maxilla,  are  immovably  united  by  sutures. 


THE  BONES  OF  THE  HEAD  55 

The  Occipital  Bone. 

The  occipital  bone  is  so  named  because  it  is  situated  against  the 
posterior  and  inferior  parts  of  the  cranium.  It  is  quadrilateral 
and  curved,  its  long  axis  extending  from  above  downwards 
and  forwards.  At  its  lower  and  anterior  part  there  is  a  large 
opening,  called  the  foramen  magnum,  by  which  the  cranial  cavity 
communicates  with  the  spinal  canal.  The  bone  is  divisible  into  four 
parts,  which  meet  around  this  opening.  The  part  behind  is  called 
the  tabular  portion,  that  in  front  the  basilar  process,  and  the  part  at 
either  side  the  condylar  portion. 

The  tabular  portion  presents  two  surfaces,  three  angles,  and  four 
borders.  The  posterior  or  external  surface  is  convex  and  projected 
at  its  centre  into  the  external  occipital  protuberance,  from  which  a 
median  ridge,  called  the  external  occipital  crest,  passes  downwards 
and  forwards  to  the  foramen  magnum.  The  protuberance  and  crest 
give  attachment  to  the  ligamentum  nuchae.  Arching  outwards  on 
either  side  from  the  protuberance  to  the  lateral  angle  there  is  the 
superior  curved  line,  the  convexity  of  which  is  directed  upwards. 
The  two  lines  with  the  protuberance  divide  this  surface  into  an  upper 
or  interparietal  and  a  lower  or  supra-occipital  part.  A  little  above 
each  superior  curved  line  there  is  the  highest  curved  line,  which  has 
a  bold  curve  with  the  convexity  upwards,  and  gradually  subsides 
in  the  superior  curved  line  externally.  Between  these  two  lines 
there  is  a  semilunar  area,  over  which  the  bone  is  smooth  and  dense. 
The  highest  curved  line  gives  attachment  to  the  epicranial  apo- 
neurosis internally,  and  to  fibres  of  the  occipitalis  externally.  The 
superior  curved  line  gives  origin  over  about  its  inner  third  to  the 
trapezius,  and  externally  to  fibres  of  the  occipitalis,  whilst  over  its 
outer  half,  or  more,  it  gives  insertion  to  the  sterno-cleido-mastoid, 
immediately  below  which  the  splenius  capitis  is  inserted  over  about 
the  outer  third.  The  portion  of  this  surface  above  the  highest 
curved  lines  is  smooth,  convex,  and  covered  by  the  epicranial  apo- 
neurosis. The  portion  below  the  superior  curved  lines,  which  is 
rough  and  irregular,  is  divided  into  two  equal  lateral  parts  by  the 
crest,  and  each  of  these  is  subdivided  into  an  upper  and  lower 
portion  by  the  inferior  curved  line,  which  extends  from  the  centre 
of  the  crest  to  the  extremity  of  the  jugular  process.  The  space 
between  the  superior  and  inferior  curved  lines  gives  insertion 
internally  to  the  complexus,  and  externally,  from  above  down- 
wards, to  the  splenius  capitis  and  obliquus  capitis  superior.  The 
inferior  curved  line  gives  insertion  over  its  outer  part  to  the  rectus 
capitis  posticus  major.  The  inner  third  of  this  line  and  the  surface 
between  that  extent  of  it  and  the  foramen  magnum  give  insertion 
to  the  rectus  capitis  posticus  minor. 

The  anterior  or  internal  surface  is  irregularly  concave  and  divided 
into  four  fossje  by  two  ridges — a  longitudinal,  extending  from  the 
superior  angle  to  the  foramen  magnum,  and  a  transverse,  extending 
from  one  lateral  angle  to  the  other.     At  the  point  where  these  two 


56 


A  MANUAL  OF  ANATOMY 


ridges  intersect  there  is  the  internal  occipital  protuberance.     The 

upper  half  of  the  longitudinal  ridge  gives  attachment  to  a  portion  of 
the  falx  cerebri,  and  is  marked  by  a  groove  for  the  superior  longi- 
tudinal venous  sinus,  this  groove  being  confined  to  one  side  of  it, 
usually  the  right.  The  lower  half  is  sharp  and  wiry,  and  is  called  the 
internal  occipital  crest.     It  gives  attachment  to  the  falx  cerebelli, 


Upper  or  Interparietal  part 
of  Tabular  Portion 


External  Occipital  Crest 

Highest  Curved  Line 
Complexus^ 


External  Occipital  Protuberance 
/ '   /  Trapezius 

'  Superior  Curved  Line 


Inferior  Curved  Line 
4  /Occipitalis 


Rectus  Capitis 
Posticus  Minor 


Obliquus 
Capitis 
Superior 


Rectus  Capitis  _ 
Posticus  Major 


Rectus  Capitis 

Lateralis 


Posterior  Condylar  Fossa  and 
Foramen  (latter  inconstant) 
Anterior  Condylar  Foramen 
Rectus  Capitis  Anticus  Minor  ' 

Rectus  Capitis  Anticus  Major 


Sterno-cleido-mastoid 


Splenius  Capitis 


-.Lateial  Angle 


Inferior  Lateral 

Border  of 
Tabular  Portion 


Jugular  Process 


Jugular  Notch 
Condyle 


Pharyngeal  Tubercle  on 
Basilar  Process 


Fig.   39. — The  Occipital  Bone  (External  View). 


and  is  occasionally  grooved  for  the  occipital  venous  sinus.  Near 
the  foramen  magnum  it  divides  into  two  parts,  which  diverge  as 
they  pass  to  that  opening,  and  enclose  between  them  the  vermiform 
fossa,  which  receives  a  part  of  the  vermiform  process  of  the  cere- 
bellum. The  transverse  ridge  gives  attachment  to  the  tentorium 
cerebelli,  and  is  deeply  grooved  along  each  half  for  the  lateral  venous 
sinus.     On  one  side  of  the  internal  occipital  protuberance,  usually 


THE  BOXES  OF  THE  HEAD  57 

the  right,  there  is  a  wide  depression,  at  which  point  the  longitudinal 
groove  is  continued  into  the  corresponding  lateral  groove.  This 
depression  lodges  the  torcular  Herophili,  which  is  a  dilatation 
formed  where  the  superior  longitudinal  sinus  bends  sharply  to 
become  continuous  with  the  right  lateral  sinus.  The  four  fossae 
are  arranged  in  a  superior  pair,  called  superior  occipital  or  cerebral, 
and  an  inferior  pair,  called  inferior  occipital  or  cerebellar.  Each 
cerebral  fossa  presents  a  number  of  digitate  impressions  for  the 
convolutions  of  the  occipital  lobe  of  the  cerebrum,  which  is  lodged 
in  it.  The  cerebellar  fossa;,  which  are  separated  by  the  internal 
occipital  crest,  are  smooth,  but  may  show  transverse  striations. 
They  are  much  thinner  than  the  cerebral,  and  lodge  the  hemispheres 
of  the  cerebellum. 

The  angles  are  superior  and  two  lateral.  The  superior  angle 
forms  the  highest  part  of  the  bone,  and  fits  in  between  the  postero- 
superior  angles  of  the  parietals.  The  lateral  ansfles  are  situated 
at  either  end  of  the  transverse  ridge  on  the  internal  surface. 

The  borders  are  two  superior  and  two  inferior.  Each  superior 
border  extends  from  the  superior  angle  to  the  lateral  angle,  and  is 
serrated  for  the  posterior  border  of  the  corresponding  parietal.  Each 
inferior  border  extends  from  the  lateral  angle  to  the  jugular  process, 
and  is  faintly  serrated  for  the  mastoid  portion  of  the  temporal. 

The  basilar  process  (basi-occipital)  is  a  compressed  quadrilateral 
mass,  which  projects  forwards  and  upwards  in  front  of  the  foramen 
magnum.  Its  superior  surface  presents  a  broad  median  depression, 
called  the  basilar  groove,  which  is  sloped  downwards  and  back- 
wards to  the  foramen  magnum,  and  lodges  the  medulla  oblongata. 
At  either  side  of  this  groove  there  is  a  narrow  groove  for  the  inferior 
petrosal  venous  sinus.  The  inferior  surface  presents  at  its  centre 
the  pharyngeal  tubercle  for  the  fibrous  raphe  of  the  pharynx.  On 
either  side  of  this  tubercle  there  is  a  rough,  oblique  impression  for 
the  insertion  of  the  rectus  capitis  anticus  major,  and  between  the 
outer  part  of  this  impiession  and  the  foramen  magnum  the  surface 
gives  insertion  to  the  rectus  capitis  anticus  minor.  The  anterior 
border  is  thick,  rough,  and  truncated,  and  up  to  the  twentieth 
year  it  a"ticulates  with  the  body  of  the  sphenoid  by  synchon- 
drosis, but  thereafter  ankylosis  takes  place.  The  posterior  border, 
which  is  thin,  smooth,  and  concave,  bounds  anteriorly  the  foramen 
magnum,  and  sometimes  presents  a  third  occipital  condyle  of  small 
size  for  articulation  with  the  tip  of  the  odontoid  process  of  the  axis. 
This  border  gives  attachment  to  the  middle  odontoid  or  suspensory 
ligament.  Each  lateral  border  is  thick  and  rough  for  the  petrous 
portion  of  the  temporal. 

The  condylar  portions  (exoccipitals)  are  placed  on  either  side  of  the 
foramen  magnum,  where  they  extend  as  far  back  as  its  posterior 
margin,  and  very  nearly  as  far  forwards  as  its  anterior  margin. 
Each  bears  on  its  under  surface  a  condyle.  The  condyles  are  oval, 
convex,  and  covered  by  cartilage,  and  thi'y  articulate  with  the 
superior    articular    processes    of   the    atlas.     Their   long  axes  are 


A  MANUAL  OF  ANATOMY 


directed  forwards  and  inwards,  and  the  direction  of  each  surface 
is  downwards  and  slightly  outwards.  They  do  not  extend  farther 
back  on  the  lateral  margins  of  the  foramen  magnum  than  the  level 
of  the  centre,  and  the  front  part  of  each  belongs  to  the  basilar  portion. 
The  circumference  of  a  condyle  gives  attachment  to  the  capsular 
ligament  of  the  corresponding  occipito-atlantal  joint,  and  on  the 
inner  aspect  of  each  there  is  a  tubercle  for  the  lateral  odontoid  or 
check  ligament.     External  to  the  front   of  each  condyle  is   the 


Depression  for  Torcular  Herophili 


Groove  for  Superior  Longitudinal 
Sinus 

Cerebral  Fossa 


Superior  Lateral 
Border 


Lateral  An 


Inferior  Lateral 
Border 


Posterior  Condj 
Foramen 


Cerebellar  Fossa 

Vermiform  Fossa 

■~^Groove  for  Lateral 
Sinus 

"  Jugular  Process 


Jugular  Notch 


P~IG.    40. 


Basilar  Groove 


Basilar  Process 

-The  Occipital  Bone  (Internal  View) 


anterior  condylar  foramen,  which  opens  forwards  and  outwards  from 
the  cranial  cavity.  It  transmits  the  hypoglossal  nerve  and  a 
meningeal  branch  of  the  ascending  pharyngeal  artery.  Behind 
each  condyle  is  the  posterior  condylar  fossa,  which  may  be  pierced 
by  a  posterior  condylar  foramen,  on  one  or  both  sides,  for  an 
emissary  vein  passing  between  the  intracranial  lateral  sinus  and 
the  extracranial  suboccipital  venous  plexus.  The  part  external 
to  the  condyle  is  called  the  jugular  process,  which  lies  above  the 


THE  BONES  OF  THE  HEAD  59 

transverse  process  of  the  atlas,  and  is  homologous  with  it.  Pos- 
teriorly it  is  continuous  with  the  tabular  portion,  and  anteriorly  it 
presents  the  jugular  notch,  which,  with  the  jugular  fossa  of  the 
petrous  portion  of  the  temporal,  forms  the  jugular  foramen. 
Superiorly  it  presents  a  short,  but  deep  and  wide,  groove  for  a  portion 
of  the  lateral  venous  sinus  just  before  it  leaves  by  the  jugular  fora- 
men. This  groove  may  be  pierced  by  a  posterior  condylar  fora- 
men. Inferiorly  it  gives  attachment  to  the  rectus  capitis  lateralis, 
and  may  send  downwards  a  projection  towards  the  transverse 
process  of  the  atlas,  which  represents  the  paramastoid  process  of  com- 
parative anatomy.  Externally  the  jugular  process  articulates  with 
the  jugular  facet  on  the  petrous  portion  of  the  temporal  by  synchon- 
drosis up  to  the  twenty-tifth  year,  after  which  ankylosis  takes  place. 

The  foramen  magnum  is  situated  at  the  lower  and  anterior  part 
of  the  bone,  and  is  oval,  its  long  axis  extending  from  before  back- 
wards. The  inferior  margin,  in  front  of  the  condyles,  gives  attach- 
ment to  the  anterior  occipito-atlantal  ligament,  and,  behind  them,  to 
the  posterior  occipito-atlantal  ligament.  The  foramen  transmits 
the  medulla  oblongata  and  its  membranes,  the  spinal  accessory 
nerves,  the  vertebral  arteries,  and  the  anterior  and  posterior  spinal 
arteries. 

The  chief  blood-supply  of  the  bone  is  derived  from  the  occipital 
and  posterior  auricular  arteries. 

Articulations. — Superiorly  with  the  parietals,  laterally  with  the 
temporals  (mastoid  and  petrous  portions),  anteriorly  with  the 
sphenoid,  and  inferiorly  with  the  atlas,  and  in  rare  cases  with  the 
odontoid  process  of  the  axis. 

Structure. — The  occipital,  being  a  tabular  bone,  is  composed  of 
two  tables  of  compact  bone,  with  cancellated  tissue,  called  diploe, 
between  them. 

Varieties. — (i)  There  may  be  a  minute  foramen  piercing  the  external 
occipital  protuberance  for  an  emissary  vein,  which  passes  between  the  intra- 
cranial torcular  Herophili  and  one  of  the  tributaries  of  the  extracranial 
occipital  vein.  (2)  The  upper  division  of  the  tabular  portion  may  be  separate, 
representing  the  interparietal  bone  of  comparative  anatomy,  and  it  may  be  in 
one  piece,  or  in  two  or  more.  (3)  The  semilunar  area  between  the  highest 
and  superior  curved  lines  may  be  prominent,  constituting  the  torus  occipitalis 
tvansversus.  (4)  The  anterior  condylar  foramen  may  be  double  on  its  cranial 
aspect.  (5)  There  may  be  a  third  occipital  condyle  on  the  anterior  margin 
of  the  foramen  magnum.  (6)  There  may  be  a  paramastoid  process  on  the 
under  aspect  of  the  jugular  process.  (7)  The  condyle  may  be  divided  into 
two  parts,  anterior  and  posterior.  (8)  There  may  be  an  intra] ugular  process 
on  the  front  of  the  jugular  notch,  which  may  extend  as  far  as  the  petrous 
portion  of  the  temporal. 

Ossification. — The  bone  is  developed  in  four  parts.  The  tabular  portion 
usually  ossifies  from  four  centres,  which  appear  around  the  internal  occipital 
protuberance  about  the  eighth  week  of  intra-uterine  life.  Two  are  deposited 
in  cartilage,  one  for  each  cerebellar  fossa,  which  soon  fuse  and  give  rise  to 
the  lower  or  supra-occipital  division.  The  other  two  arc  deposited  in  membrane, 
one  in  each  cerebral  fossa,  which  also  soon  fuse  and  give  rise  to  the  upper 
or  interparietal  division.  Indeed,  as  a  general  rule,  all  four  ultimately  blend. 
There  may,  however,  be  two  other  centres  for  the  interparietal  portion,  placed 


6o 


A  MANUAL  OF  ANATOMY 


on  either  side  of  the  middle  Une  not  far  from  the  future  superior  angle,  which 
occasionally  remain  as  separate  ossicles,  or  they  may  fuse  and  give  rise  to 
the  pre-interparietals.  The  interparietal  portion  may  remain  separate  from 
the  supra-occipital,  with  which  it  may  be  connected  by  a  suture,  or  they  may 
be  separated  by  a  partial  fissure.  Fissures,  which  persist  for  some  time  after 
birth,  intersect  the  tabular  part  at  the  superior  and  lateral  angles,  and  a 
membranous  interval  extends  from  the  protuberance  to  the  foramen  magnum 
in  early  life,  which  remains  for  some  weeks,  after  which  it  is  replaced  by  bone. 


Tabular  Part.    4  Centres,  which  appear 

about  the  8th  Week 

(intra-uterine) 


-  Condylar  Part,     i  Centre,  which  appears 
about  the  gth  Week  (intra-uterine) 

.    Basilar  Part,     i  Centre,  which  appears 
about  the  gth  Week  (intra-uterine) 

Fig.  41. — Ossification  of  the  Occipital  Bone. 
(The  figure  shows  the  condition  of  the  bone  at  birth.) 

It  is  in  tliis  latter  situation  where  an  encephalocele  may  occur.  The  basilar 
and  condylar  parts  have  each  one  centre  appearing  in  cartilage  about  the 
ninth  week,  the  anterior  part  of  each  condylar  portion  deriving  its  ossification 
from  the  basilar  centre.  At  birth  the  bone  is  in  four  parts,  connected  by 
cartilage.  Union  between  the  tabular  and  condylar  portions  is  completed 
by  the  fourth  year,  and  the  condvlar  and  basilar  portions  unite  about  the 
sixth  year.  After  the  twentieth  year  the  basilar  portion  joins  the  sphenoid, 
and  at  the  twenty -fifth  year  the  jugular  process  becomes  ankylosed  to  the 
petrous  portion  of  the  temporal. 


The  Parietal  Bones. 

The  parietal  bones  are  so  named  because  they  form  a  large 
part  of  the  cranial  wall.  They  lie  between  the  frontal  and 
occipital,  and  superiorly  they  articulate  with  each  other  by 
the  sagittal  or  interparietal  suture.  Each  bone  is  quadrilateral 
and  curved,  and  presents  two  surfaces,  four  borders,  and  four 
angles.  The  external  surface  is  convex,  and  near  its  centre  is  more 
elevated  than  elsewhere,  this  part,  from  which  ossification  originally 
proceeds,  being  called  the  parietal  eminence.  A  little  below  this 
the  surface  is  crossed  from  before  backwards  by  two  curved  lines, 
called  the  superior  and  inferior  temporal  ridges,  the  narrow  space 
between  which  is  smoother  and  more  glistening  than  the  rest  of 
the  surface.  The  part  above  the  superior  ridge  is  covered  by  the 
epicranial  aponeurosis,  and  the  ridge  itself  gives  attachment  to"[the 
temporal  fascia.     The  inferior  temporal  ridge  limits  the  origin  of  the 


THE  BONES  OF  THE  HEAD 


temporal  muscle,  and  the  portion  between  it  and  the  inferior  border, 
which  is  vertically  striated  and  called  the  planum^  temporale, 
forms  a  part  of  the  temporal  fossa,  and  gives  origin  to  fibres  of  the 
temporal  muscle.  Near  the  superior  border,  about  an  inch  in  front 
of  the  postero-superior  angle,  is  the  parietal  foramen,  for  an  emissary 
vein  which  passes  between  the  intracranial  superior  longitudinal 
sinus  and  one  of  the  tributaries  of  the  extracranial  occipital  vein. 

The  internal  surface  is  concave,  its  deepest  part,  opposite  the 
parietal  eminence,  being  known  as  the  parietal  fossa.  This  surface 
presents  a  number  of  digitate  impressions  for  the  convolutions  of 


Superior  Border 


Parietal  Foramen 


Anterior  Border 


Posterior  Border 


Superior  Temporal 
Ridge 

Inferior  Border  Inferior  Temporal  Ridge 

PiG_  42. — The  Right  Parietal  Bone  (External  View). 

the  parietal  and  part  of  the  frontal  lobes  of  the  cerebrum,  and  a 
system  of  branching  meningeal  grooves  for  the  divisions  of  the 
middle  meningeal  artery.  These  commence  as  two  grooves,  each 
of  which  soon  becomes  arborescent.  The  anterior,  the  larger  of 
the  two,  commences  on  the  inner  surface  of  the  antero-inferior 
angle,  where  it  may  be  bridged  over  into  a  short  canal,  and  the 
posterior  starts  from  the  centre  of  the  inferior  border.  Superiorly, 
close  to  the  superior  border,  there  is  a  half  groove  which,  with 
that  of  the  ojjposite  bone,  lodges  the  superior  longitudinal  venous 
smus.  Along  the  course  of  this  groove,  but  external  to  it,  are 
several  depressions,  best  marked  in  old  persons,  which  lodge  the 


62 


A  MANUAL  OF  ANATOMY 


Pacchionian  bodies.     Close  to  the  postero-inferior  angle  there  is  a 
short  groove  for  part  of  the  lateral  venous  sinus. 

Borders. — The  posterior,  anterior,  and  superior  borders  are 
serrated.  The  posterior  border  articulates  with  the  occipital ;  the 
superior,  with  its  fellow ;  and  the  anterior  with  the  frontal.  The 
anterior  border  is  bevelled  below  at  the  expense  of  the  inner  plate, 
where  it  overlaps  the  frontal,  and  it  is  slightly  bevelled  above  at  the 
expense  of  the  outer  plate,  where  it  is  overlapped  by  the  frontal. 
The  inferior  border,  which  is  the  shortest,  is  for  the  most  part 
concave  and  markedly  bevelled  at  the  expense  of  the  outer  plate, 

Superior  Border  and 
Groove  for  Superior  Longitudinal  Sinus 


Pacchionian  Depressions 


Parietal  Foramen 


Anterion. 
Border 


Antero-inferior  Angle 
Anterior  Meningeal  Groove 


f  jiJi_  Posterior 

f      ,,„"'^>"'"~''^it_  Jfff       Border 


Posterior  Meningeal  Groove 
at  Inferior  Border 


I   Postero-inferior  Angle 
Groove  for  Lateral  Sinus 


Fig.  43. — The  Right  Parietal  Bone  (Internal  View). 


where  it  is  overlapped  by  the  squamous  portion  of  the  temporal. 
Posteriorly,  however,  it  is  serrated  for  the  superior  border  of  the 
mastoid  portion  of  the  temporal. 

Angles. — The  ant ero- superior  angle,  with  its  fellow,  lies  in  the 
situation  of  the  original  anterior  fontanelle.  The  postero-superior 
angle,  with  its  fellow,  occupies  the  region  of  the  original  posterior 
fontanelle.  The  postero-inferior  angle  is  truncated,  and  articulates 
with  the  mastoid  portion  of  the  temporal,  being  also  recognised 
by  the  short  groove  for  the  lateral  venous  sinus  on  its  inner 
aspect.  The  antero-inferior  angle  is  prolonged  and  pointed, 
and  articulates  with  the  great  wing  of  the  sphenoid,   being  also 


THE  BONES  OF  THE  HEAD  63 

recognised  by  the  large  anterior  meningeal  groove  on  its  inner 
surface. 

The  bone  receives  its  chief  blood-supply  from  the  middle 
meningeal  artery  internally,  and  the  occipital  externally. 

Articulations. — Posteriorly  with  the  occipital,  superiorly  with  its 
fellow,  anteriorly  with  the  frontal,  antero-inferiorly  with  the  sphenoid, 
and  inferiorly  with  the  temporal. 

Structure. — It  is  a  characteristic  tabular  bone. 

Varieties. — (i)  The  bone  may  persist  in  two  parts,  upper  and  lower,  con- 
nected by  an  antero-posterior  suture.  (2)  The  parietal  foramen  may  be  absent 
on  one  or  both  sides. 

OssiGcation. — The  parietal  ossifies  in  membrane  from  two  centres,  which 
appear  about  the  seventh  week  in  the  region  of  the  future  parietal  eminence, 
one  above  and  the  other  below  it,  and  soon  coalesce.     The  ossification  radiates 


.    Appear  about  the 
7  th  Week 
(intra-ulerine) 


Fig.  44. — Ossification  of  the  Parietal  Bone. 

from  this  point  in  such  a  manner  as  to  leave  a  notch  on  the  upper  border  a 
little  in  front  of  the  postero-superior  angle,  which  forms  one-half  of  the  sagittal 
fontanelle  of  the  earlier  half  of  foetal  life. 


The  Frontal  Bone. 

The  frontal  bone  forms  the  forehead  and  greater  part  of  the 
roof  of  each  orbit,  and  it  lies  in  front  of  the  parietals.  It  is  divisible 
into  a  frontal  portion  and  two  orbital  plates,  the  latter  being 
situated  inferiorly,  where  they  are  separated  by  the  ethmoidal  notch. 

The  frontal  portion  presents  two  surfaces,  external  and  internal. 
The  external  surface,  which  is  smooth  and  convex,  presents  a  little 
below  its  centre,  on  either  side,  an  elevation,  called  the  frontal 
eminence.  Below  this,  and  separated  from  it  by  a  shallow  groove, 
there  is  the  curved  superciliary  ridge  which  supports  the  eyebrow. 
This  ridge  is  prominent  internally,  but  it  subsides  externally.  It 
supports  the  upper  half  of  the  orbicularis  palpebrarum,  and 
internally  it  gives  origin  to  the  corrugator  supercilii,  whilst  the 
surface  above  each  ridge  supports  the  frontalis  and  part  of  the 
epicranial  aponeurosis.  Between  the  two  superciliary  ridges  is  an 
elevation,  called  the  nasal  eminence  or  glabella.  Below  each  ridge 
is  the  curved  supra-orbital  arch,  which  is  most  prominent  over  its 


64 


A  MANUAL  OF  ANATOMY 


outer  two- thirds.  At  the  junction  of  the  inner  third  and  outer 
two-thirds  is  the  supra-orbital  notch,  sometimes  a  foramen,  for  the 
passage  of  the  supra-orbital  nerve  and  artery.  Occasionally  there 
is  a  frontal  notch,  inside  the  normal  notch,  for  a  branch  of  the 
supra-orbital  nerve.  The  extremities  of  the  supra-orbital  arch 
form  the  external  and  internal  angular  processes.  The  external 
process  is  stout  and  serrated  for  articulation  with  the  malar.  The 
internal  process  is  faintly  marked,  and  lies  by  the  side  of  the  nasal 


Parietal  Border 


Superior  Temporal  Ridge 


Inferior 
Temporal  Ridge 


Frontal  Eminence 


Temporal  Surface  for 
Temporal  Muscle 


Lachrymal  Fossa 


Glabella      / 
/ 

Nasal  Process 


NExternal 
\  Angular  Process 

Superciliary  Ridge 
Supra-orbital  Notch 


Internal  Angular  Process 


Nasal  Spine 

Fig.  45.— The  Frontal  Bone  (Anterior  View). 

notch,  where  it  articulates  with  the  lachrymal,  and  gives  origin  to 
some  fibres  of  the  orbicularis  palpebrarum. 

On  the  lateral  aspect  of  the  external  surface  there  are  two  curved 
lines  called  the  superior  and  inferior  temporal  ridges,  the  superior 
being  faint  and  the  inferior  bold.  They  spring  from  the  external 
angular  process,  and  arch  upwards  and  backwards  to  become  con- 
tinuous with  the  corresponding  ridges  on  the  parietal.  The  superior 
gives  attachment  to  the  temporal  fascia,  and  the  inferior  limits 
the  temporal  muscle,  which  arises  from  it  and  the  surface  below, 
this  latter  forming  a  part  of  the  temporal  fossa.     Below  the  glabella 


THE  BONES  OF  THE  HEAD  65 

on  the  under  aspect  there  is  a  rough,  semihmar,  serrated  surface 
for  articulation  with  the  nasal  bones  and  nasal  processes  of  the 
superior  maxilLx,  and  behind  this  is  the  nasal  notch,  bounded  at 
either  side  by  the  internal  angular  process.  Within  the  notch  is 
the  nasal  process,  which  supports  the  nasal  bones,  and  projecting 
downwards  from  it  is  the  sharp  nasal  spine,  which  articulates  in 
front  with  the  upper  part  of  the  crest  of  the  nasal  bones,  and  behind 
with  the  vertical  plate  of  the  ethmoid.  This  spine  enters  into  the 
nasal  septum.  On  either  side  of  the  spine  is  the  ala,  which  is 
grooved  to  take  part  in  the  roof  of  the  corresponding  nasal  fossa. 

The  internal  or  cerebral  surface  of  the  frontal  portion  is  concave, 
and  in  the  middle  line  presents  a  groove,  called  the  frontal  sulcus, 
which  lodges  a  part  of  the  superior  longitudinal  venous  sinus. 
On  either  side  of  the  upper  part  of  this  groove  there  are  a  few 
depressions  for  the  Pacchionian  bodies.  Inferiorly  the  groove  is 
replaced  by  the  frontal  crest,  which  terminates  at  the  foramen 
caecum.  This  foramen  is  sometimes  partly  formed  by  the  crista 
galli  of  the  ethmoid,  and  it  may  be  closed  below,  or  it  may  transmit 
an  emissary  vein,  which  passes  between  the  intracranial  superior 
longitudinal  sinus  and  the  veins  of  the  roof  of  the  nose.  The 
internal  surface  presents  numerous  digitate  impressions  for  the 
convolutions  of  the  frontal  lobes  of  the  cerebrum,  and  laterally 
there  are  a  few  meningeal  grooves,  transversely  disposed,  for 
branches  of  the  middle  meningeal  arteries. 

The  supero-lateral  or  parietal  border  of  the  frontal  portion  is 
serrated  for  the  parietal  bones.  Superiorly  it  is  slightly  bevelled 
near  the  middle  line  at  the  expense  of  the  inner  plate,  where  it  over- 
laps the  parietal,  and  at  either  lower  extremity  it  is  distinctly 
bevelled  at  the  expense  of  the  outer  plate,  where  it  is  overlapped 
by  the  parietal.  Internal  to  its  lower  termination  at  either  side 
there  is  a  rough  triangular  surface,  which  is  serrated  for  the  great 
wing  of  the  sphenoid. 

The  orbital  plates,  thin  and  brittle,  project  backwards  in  a 
curved  manner  from  the  supra  -  orbital  arches,  and  are  widely 
separated  by  the  ethmoidal  notch,  which  is  occupied  by  the  cribri- 
form plate  of  the  ethmoid.  Each  is  triangular,  with  the  truncated 
apex  directed  backwards  and  inwards,  and  presents  two  surfaces 
and  three  borders.  The  superior  or  cerebral  surface  is  irregularly 
convex,  and  marked  by  digitate  impressions  for  the  convolutions 
of  the  orbital  surface  of  the  frontal  lobe,  which  rests  upon  it. 
The  inferior  or  orbital  surface,  smooth  and  concave,  forms  the 
principal  part  of  the  roof  of  the  orbit.  Within  the  external  angular 
process  is  the  lachrymal  fossa,  which  lodges  the  lachrymal  gland, 
and  near  to  the  internal  angular  process  is  the  small  trochlear  fossa, 
which  gives  attachment  to  the  trochlea  of  the  sui)erior  oblique 
muscle  of  the  eyeball. 

The  borders  are  anterior,  external,  and  internal.  The  anterior 
border  rej^resents  the  suj)ra-orbital  arch,  and  is  free.  The  external 
border  is  sharp  and  irregular,  and  its  ditectionjiis  backwards  and 

3 


66 


A  MANUAL  OF  ANATOMY 


inwards.  It  forms  a  right  angle  with  its  fellow  of  the  opposite 
side,  and  abuts  against  the  great  wing  of  the  sphenoid.  The 
internal  border  is  directed  from  before  backwards,  is  parallel  with 
its  fellow  of  the  opposite  side,  and  forms  the  lateral  boundary  of 
the  ethmoidal  notch.  It  is  bevelled  at  the  expense  of  the  lower 
plate,  and  the  bevelled  surface  presents  several  excavations,  which 
close  in  the  ethmoidal  cells  on  the  upper  border  of  the  lateral 
mass  of  the  ethmoid.  This  surface  is  crossed  by  two  transverse 
grooves,  anterior  and  posterior,  which,  with  similar  grooves  on  the 
contiguous  part  of  the  ethmoid,  form  the  anterior  and  posterior 
ethmoidal  (internal  orbital)  canals.     These  open  on  the  inner  wall 


Nasal  Spine 


Ala 


For  Nasal  Process  of 
■  Superior  Maxilla    ^ 

V 

Frontal  Sinus      \ 


Tiochlear  Fossa 


Frontal  Crest  and  Ethmoidal  Notch 
/ 

(        Nasal  Notch 
/        '         Groove  for  Ant.  Ethmoidal  Canal 

'       /        /      Supra-orbital  Notch 

/      /        /      / 

Orbital  Plate 

Lachrymal  Fossa 

Ext.  Angular  Process 


Surf,  for  Great 
Wing  of  Sphenoid 


For  Small  Wing 
of  Sphenoid 


Frontal  Sulcus 


Groove  for  Posterior 
Ethmoidal  Canal 


Parietal  Border 

Fig.  46. — The  Frontal  Bone  (Inferior  View). 


of  the  orbit,  and  the  anterior  gives  passage  to  the  nasal  nerve  and 
anterior  ethmoidal  vessels,  whilst  the  posterior  transmits  the  posterior 
ethmoidal  vessels  and  spheno-ethmoidal  nerve.  The  truncated 
apex  of  the  orbital  plate  articulates  with  the  small  wing  of  the 
sphenoid. 

In  front  of  the  anterior  ethmoidal  groove  on  either  side  is  the 
opening  of  the  frontal  air  sinus.  Each  leads  into  a  cavity  within 
the  bone,  which  extends  outwards  from  near  the  middle  line  for 
a  variable  distance  behind  the  superciliary  ridge.  The  sinuses  are 
separated  by  a  median  septum,  and  may  be  unilocular  or  multi- 
locular.     In  the  latter   case   the  subdivisions  may  extend  back- 


THE  BONES  OF  THE  HEAD 


67 


wards  for  a  variable  distance  within  the  roof  of  the  orbit.  Each 
sinus  is  hned  by  mucous  membrane  continuous  with  that  of  the 
corresponding  nasal  fossa,  with  which  it  communicates  by  a  passage 
called  the  infundibulum. 

The  bone  derives  its  blood-supply  from  the  middle  meningeal, 
meningeal  branches  of  the  internal  carotid,  and  anterior  and 
posterior  ethmoidal  arteries  internally,  and  the  supra-orbital  and 
frontal  arteries  externally. 

Articulations. — These  are  twelve  in  number,  as  follows  :  pos- 
teriorly with  the  two  parietals  above,  and  the  sphenoid  (great  and 
small  wings)  below  ;  by  the  external  angular  processes  with  the 
two  malars  ;  between  the  orbits  with  the  two  nasals,  two  superior 
maxillae,  and  two  lachrymals  ;  and  in  the  middle  line  with  the 
lateral  masses  and  vertical  plate  of  the  ethmoid. 

Structure. — It  is  a  tabular  bone.  The  oi"bital  plates,  being 
destitute  of  diploe,  are  thin  and  translucent,  except  in  those  cases 
where  extensions  of  the  frontal  air  sinuses  invade  them. 


Varieties. — (i)  There  may  be  a  persistent  frontal  suture,  called  the  metopic 
suture,  tliis  condition  being  known  as  metopisni.  (2)  Wormian  bones  are 
sometimes  met  with  at  the  centre 
of  the  supero-lateral  border  in  the 
region  of  the  anterior  fontanelle, 
and,  if  these  remain  permanent,  they 
give  rise  by  their  union  to  a  breg- 
matic  bone. 


OssiGcation. — The  frontal  ossifies 
in  membrane  from  two  centres,  one 
for  each  half,  which  appear  about 
the  seventh  week  of  intra-uterine  life 
in  the  situation  of  the  future  frontal 
eminences.  At  birth  the  bone  con- 
sists of  two  halves  united  by  mem- 
brane, and  in  the  course  of  the 
first  year  they  become  united  by  a 
vertical  frontal  or  metopic  suture. 
This  suture  gradually  becomes  ob- 
literated from  below  upwards,  and 
usually  disappears  about  the  sixth 
year,  though  slight  traces  may  persist  above  and  below,  especially  in  the  latter 
situation.  Three  pairs  of  secondary  centres  are  described,  two  mesially 
placed  for  the  nasal  spine,  one  at  either  side  in  the  region  of  the  future  trochlear 
fossa,  and  one  for  each  external  angular  process.  The  frontal  air  sinuses  begin 
to  appear  about  the  seventh  year,  but  they  do  not  attain  any  size  till  after 
puberty.     They  are  rather  larger  in  the  male  than  in  the  female. 


Fig. 


Appears  about  the  7th  Week 
(intra-uterine) 

47. — Ossification  of  the 
Frontal  Bone. 


The  Temporal  Bones. 

The  temporal  bones  (ossa  temporis)  are  so  named  because  the  hair 
over  the  temple  is  the  first  to  become  gray,  thus  indicating  advance 
in  life,  liach  bone  is  situated  on  the  lateral  aspect  of  the  head 
below  the  parietal.  For  convenience  of  description  each  is  divided 
into  three  parts,  namely  :  the  squamous  portion,  which  bears  the 

5—2 


68  A  MANUAL  OF  ANATOMY 

zygoma  ;  the  mastoid  portion  ;  and   the   petrous  portion,  which 
bears  inferiorly  the  styloid  process. 

The  squamous  portion  (squamo-zygomatic)  hes  almost  vertically, 
and  presents  two  surfaces,  outer  and  inner,  and  a  superior  border. 
The  outer  surface  is  convex  towards  its  centre,  and  forms  a  large 
part  of  the  temporal  fossa.  It  gives  origin  to  fibres  of  the  temporal 
muscle,  and  is  marked  by  a  groove  for  the  middle  temporal  artery, 
which  extends  upwards  and  slightly  forwards  from  a  point  just 
above  the  external  auditory  meatus  to  the  superior  border.  The 
inner  surface,  which  is  concave,  is  related  to  the  temporo-sphenoidal 
lobe  of  the  cerebrum,  and  presents  a  few  digitate  impressions  and 
meningeal  grooves.  The  superior  border  is  much  arched,  and 
describes  about  two-thirds  of  a  circle.  Except  over  the  lower 
part  of  its  anterior  portion,  it  is  markedly  bevelled  at  the  expense 
of  the  inner  plate  for  the  parietal,  which  it  overlaps.  Anteriorly 
over  its  lower  part  it  is  thick  and  serrated  for  the  external  border 
of  the  great  wing  of  the  sphenoid.  The  place  of  junction  of  the 
squamous  and  petrous  portions  is  indicated  at  the  lower  part  of 
the  inner  surface  of  the  former  by  the  narrow  petro-squamous 
groove  or  suture. 

The  zygoma  (jugal  process)  springs  from  the  lower  part  of  the 
outer  surface  of  the  squamous  portion.  Its  base  is  compressed 
from  above  'downwards,  and  directed  outwards.  It  then  under- 
goes a  twist,  and  is  directed  forwards  in  a  curved  manner,  being 
laterally  compressed.  This  part  of  it  presents  two  borders,  two 
surfaces,  and  an  extremity.  The  superior  border,  sharp  and  convex, 
extends  farther  forwards  than  the  inferior,  and  gives  attachment 
to  the  temporal  fascia  in  two  divisions.  The  inferior  border  gives 
origin  to  fibres  of  the  masseter.  The  outer  surface  is  convex  and 
subcutaneous,  whilst  the  inner,  which  is  concave  and  looks  towards 
the  upper  part  of  the  zygomatic  fossa,  gives  origin  to  fibres  of  the 
deep  part  of  the  masseter.  The  extremity  is  bevelled  at  the  expense 
of  the  lower  border,  and  serrated  for  the  malar.  The  base  of  the 
zygoma  presents  two  roots,  anterior  and  posterior.  The  anterior 
root,  which  is  continuous  with  the  inferior  border  of  the  process, 
is  directed  inwards  in  front  of  the  glenoid  fossa.  It  is  at  first 
narrow,  but  subsequently  thick  and  convex,  where  it  is  covered  by 
cartilage.  This  portion  is  called  the  eminentia  articularis,  and  in 
front  of  it  there  is  a  small  triangular  area  which  looks  into  the 
zygomatic  fossa.  The  posterior  root,  which  is  continuous  with  the 
superior  border  of  the  process,  passes  backwards  above  the  external 
auditory  meatus,  then  between  the  squamous  and  mastoid  portions, 
where  it  is  known  as  the  supramastoid  crest,  and  finally  it  turns 
upwards,  where  it  forms  part  of  the  posterior  boundary  of  the 
temporal  fossa.  In  front  of  the  external  auditory  meatus  it  sends 
downwards  a  short  offshoot,  which  lies  between  the  external  audi- 
tory meatus  and  the  anterior  part  of  the  glenoid  fossa.  This  is 
called  the  postglenoid  process,  and  is  sometimes  referred  to  as  the 
middle  root  of  the  zygoma. 


THE  BONES  OF  THE  HEAD 


69 


On  the  outer  surface  of  the  zygoma,  above  the  place  where  the 
anterior  root  becomes  continuous  with  its  lower  border,  there  is 
a  projection,  called  the  pre  glenoid  tubercle,  which  gives  attach- 
ment to  the  external  lateral  ligament  of  the  temporo-maxillary 
articiilation. 

Behind  the  anterior  root  is  the  glenoid  fossa,  which  extends 
on  to  the  tympanic  plate.  It  is  elongated  from  before  backwards 
and  inwards,  and  is  divided  into  two  parts  by  the  fissure  of  Glaser. 
The  anterior  part,  which  belongs  to  the  squamo-zygomatic  portion 


Squamous  Portion 


Groove  for 
Mid.  Temp.  Artery 

Suprameatal  Spine 
and  Triangle        \ 


•Supramastcid  Crest  |^^ 

Parietal  Notch 


Post.  Root  of 
Zygoma 


"'''ii&i-. 


Zygoma 


Postglenoid 
Tubercle 


Mastoid  Portion 


Mastoid  Process  / 

I 

External  Auditory  Meatus' 

Ext.  Aud.  Process 


V         Preglenoid  Tubercle 
\         \        \        \ 

\         \        \  Ant.  Root  of  Zygoma 

^^       ^       ^^  (Eminent.  Artie.) 

"^         \       Ant.  Part  of  Glenoid  B'ossa 
Fissure  of  Glaser 


Post.  Part  of  Glenoid  F'ossa 
(Tympanic  Plate) 


Vaginal  Process  ' 

Styloid  Process 

Fig.  48. — The  Right  Temporal  Bone  (External  View). 

of  the  bone,  is  covered  by  cartilage,  and  is  triangular,  with  the  apex 
at  the  preglenoid  tubercle  and  the  base  at  the  Glaserian  fissure.  It 
is  deeply  concave,  and  is  bounded  anteriorly  by  the  eminentia 
articularis,  externally  by  the  commencement  of  the  posterior  root 
of  the  zygoma,  and  posteriorly  from  without  inwards  by  the  post- 
glenoid process  and  Cilaserian  fissure.  It  articulates  with  the  condyle 
of  the  inferior  maxilla  when  the  mouth  is  closed,  an  interarticular 
fibro-cartilage  intervening ;  but,  when  the  mouth  is  open,  the  condyle 
with  the  fibro-cartilage  moves  forwards  on  to  the  eminentia  articu- 
laris.    The  i^osterior  i)art  of  the  glenoid  fossa  is  situated  behind  the 


70  A   MANUAL  OF  ANATOMY 

Glaserian  fissure,  and  is  formed  by  tlie  tympanic  plate,  whicli 
separates  it  from  the  external  auditory  meatus.  It  is  shallow, 
non- articular,  and  quadrilateral,  and  it  lodges  the  deep  part  of  the 
parotid  gland. 

The  fissure  of  Glaser,  which  is  the  remains  of  the  petro-tympanic 
fissure,  is  closed  in  its  outer  part,  and  is  divided  into  two  internally 
by  means  of  a  thin  plate  which  descends  from  the  tegmen  tym- 
pani,  and  forms  the  chief  part  of  the  outer  wall  of  the  canals  for 
the  osseous  part  of  the  Eustachian  tube  and  tensor  tympani 
muscle.  Between  this  plate  and  the  tympanic  plate  the  processus 
gracilis  of  the  malleus  is  located  internally,  and  there  is  a  small 
opening  leading  to  the  tympanic  cavity  for  the  passage  of  the 
tympanic  branch  of  the  internal  maxUlary  artery  and  the  anterior 
ligament  of  the  malleus  (so-called  laxator  tympani  muscle)  or  band 
of  Meckel.  At  the  inner  end  of  the  Glaserian  fissure  is  another 
minute  opening  leading  from  the  tympanic  cavity,  called  the  canal 
of  Huguier,  or  iter  chordae  anterius,  which  transmits  the  chorda 
tympani  nerve. 

The  mastoid  portion  is  so  named  from  the  mastoid  process  which 
it  bears.  It  is  limited  above  by  the  supramastoid  crest  and  its 
own  superior  border,  in  front  by  the  external  auditory  meatus  and 
auricular  or  tympano-mastoid  fissure,  and  behind  by  its  posterior 
border.  It  presents  two  surfaces  and  two  borders.  The  external 
surface,  rough  and  convex,  is  prolonged  downwards  behind  the 
external  auditory  meatus  into  the  mastoid  process,  which  presents 
on  its  inner  surface  two  grooves.  The  outer,  called  the  digastric 
groove,  is  deep,  and  gives  origin  to  the  posterior  belly  of  the 
digastric  ;  and  the  inner,  called  the  occipital  groove,  is  narrow,  and 
lodges  the  occipital  artery.  The  upper  part  of  the  outer  surface  of 
the  mastoid  process  gives  origin  over  its  posterior  half  to'  the 
retrahens  auriculam  and  part  of  the  occipitalis,  in  this  order  from 
before  backwards  ;  and  lower  down,  it  gives  insertion  to  the  sterno- 
cleido-mastoid,  splenius  capitis,  and  trachelo-mastoid,  in  this  order 
from  above  downwards.  At  the  upper  and  back  part  of  the 
mastoid  portion,  a  little  below  the  supramastoid  crest,  there  may 
be  the  remains  of  the  squamo-mastoid  suture  directed  downwards 
and  forwards,  indicating  the  line  of  junction  of  the  squamo-zygo- 
matic  and  basal  part  of  the  petrous  portions.  Directly  in  front 
of  the  root  of  the  mastoid  process  there  is  an  important  depressed 
area,  called  the  suprameatal  triangle  (Macewen),  which  is  bounded 
as  follows  :  above  by  part  of  the  posterior  root  of  the  zygoma,  below 
by  the  postero-superior  part  of  the  external  auditory  meatus,  and 
behind  by  a  vertical  line  connecting  the  upper  and  lower  boundaries, 
which  line  is  continuous  with  the  posterior  part  of  the  external 
auditory  meatus.  In  the  lower  part  of  the  suprameatal  triangle 
is  the  suprameatal  spine,  a  sharp,  antero-posterior  scale  of  bone, 
which  gives  attachment  to  a  portion  of  the  cartilage  of  the  external 
ear.  The  outer  surface  of  the  mastoid  portion  presents  several 
small  nutrient  foramina,  and  often  there  is  a  large  opening,  called 


THE  BONES  OF   THE  HEAD 


71 


the  mastoid  foramen,  usually  placed  near  the  posterior  border,  for 
a  large  emissary  vein,  which  passes  between  the  lateral  sinus 
internally  and  the  outermost  tributary  of  the  occipital  vein,  or 
the  posterior  auricular  vein  externally.  In  addition  to  these,  there 
is  the  minute  arterial  fissure  on  the  outer  surface  of  the  mastoid 
process  below  its  centre  for  the  mastoid  branch  of  the  occipital 
artery. 

The  inner  surface  presents  the  deep  sinuous  sigmoid  groove,  which 
lodges  a  part  of  the  lateral  venous  sinus,  and  into  which  the  mastoid 
foramen  opens.  The  genu  or  bend  of  this  groove  and  its  descend- 
ing limb  lie  behind  the  mastoid  antrum. 

The  superior  border,  thick  and  serrated,  articulates  with  the  back 
part  of  the  inferior  border  of  the  parietal.  Near  its  anterior  part 
it  presents  the  parietal  notcli,  which  receives  a  portion  of  the 
parietal  bone.  The  posterior  border,  also  thick  and  serrated, 
articulates  with  the  inferior  border  of  the  tabular  portion  of  the 
occipital. 

The  interior  of  the  mastoid  portion  contains  a  number  of  cavities 
lined  with  mucous  membrane,  called  the  mastoid  air  cells.  These 
open  into  an  irregular  chamber,  known  as  the  mastoid  antrum,  which 
is  situated  at  the  upper  part  of  the  posterior  wall  of  the  tympanum, 
and  is  lined  by  mucous  membrane  continuous  with  that  of  the 
tympanum  and  mastoid  cells.  The  upper  part  of  the  antrum  com- 
municates with  the  upper  part  or  attic  of  the  tympanum  by  an 
opening  which  faces  that  of  the  Eustachian  tube,  but  the  lower  part 
is  shut  off  from  the  tympanic  cavity,  and  its  floor  is  on  a  lower  level 
than  the  floor  of  that  cavity,  which  explains  the  difficulty  in  the 
drainage  of  fluid.  The  roof  of  the  antrum,  called  tegmen  antri,  is 
continuous  with  the  tegmen  tympani,  and  both  enter  into  the  forma- 
tion of  the  middle  fossa  of  the  base  of  the  skull.  The  outer  wall 
is  formed  by  the  squamo-mastoid  junction  in  the  region  of  the  supra- 
meatal  triangle  ;  the  floor  and  inner  wall  are  constructed  by  the 
petro-mastoid  portion  ;  and  the  posterior  wall  represents  that  part 
of  the  mastoid  portion  which  bears  the  genu  or  bend  and  descending 
limb  of  the  sigmoid  groove.  The  mastoid  cells  extend  from  the 
antrum  into  the  mastoid  i)ortion  in  a  backward  and  downward  direc- 
tion, and  are  subject  to  variety  as  regards  number  and  size.  They 
are  arranged  in  two  groups — horizontal  or  superior,  and  vertical  or 
inferior.  The  former  are  purely  pneumatic  or  air  cells,  but  the 
latter  are  of  two  kinds,  the  tipper  ones  being  pneumatic,  and  the 
lower  ones,  which  extend  to  the  tip  of  the  mastoid  process,  being 
diploetic  and  of  large  size.  Superiorly  the  cells  extend  forwards 
over  the  roof  of  the  external  auditory  meatus,  upwards  as  high  as 
the  supramastoid  crest,  and  inwards  for  a  certain  distance  into  the 
petrous  portion.  They  may  also  extend  into  the  jugular  process 
of  the  occipital  in  old  persons.  At  birth  the  mastoid  cells  are  not 
developed,  but  the  antrum  is  present. 

The  petrous  portion  is  so  named  from  its  rocky  consistence,  and 
its  direction  is  inwards  and  forwards  into  the  base  of  the  skull.     It 


72 


A  MANUAL  OF  ANATOMY 


has  the  shape  of  a  four-sided  pyramid,  and  presents  four  surfaces 
(one  of  which  is  concealed  by  the  tympanic  plate),  four  borders,  an 
apex,  and  a  base.  The  surfaces  are  superior,  posterior,  inferior,  and 
anterior. 

The  superior  surface,  which  has  an  inclination  forwards,  looks  into 
the  middle  fossa  of  the  base  of  the  skull,  and  towards  its  outer  part 
presents  a  few  digitate  impressions  for  convolutions  of  the  temporo- 
sphenoidal  lobe  of  the  cerebrum.  Near  the  apex  is  the  Gasserian 
depression  for  the  Gasserian  ganglion,  and  below  this  is  the  outlet  of 

Superior  Border  of  Squamous  Portion 


Petro-squamous 

Groove  or 

Suture 


Zygoma 


Eminentia  Arcuata 


Sigmoid  Groove  for 
Lateral  Sinus 


Meningeal  Groove 


Petro-squamous  — 
Angle 


Outlet  of  Carotid 
Canal 


Mastoid  Foramen 


Aqueductus  Vestibuli 


Internal   Auditory  Meatus 


Mastoid  Process 
Hiatus  Subarcviatus 
Aqueductus  Cochleae 
Styloid  Process 

Fig.  49. — The  Right  Temporal  Bone  (Internal  View). 

the  carotid  canal  for  the  internal  carotid  artery.  Proceeding  back- 
wards and  outwards,  there  is  a  small  groove  leading  to  a  foramen 
very  nearly  in  line  with  the  petro-squamous  angle,  called  the  hiatus 
Fallopii,  within  the  thin  margin  of  which  there  may  be  two  openings. 
The  inner  and  larger  of  these  openings  leads  to  the  commencement 
of  the  aqueduct  of  Fallopius,  and  thence  to  the  internal  auditory 
meatus,  and  it  transmits  the  great  superficial  petrosal  nerve,  along 
with  the  petrosal  branch  of  the  middle  meningeal  artery.  The 
outer  opening,  of  small  size,  also  leads  to  the  aqueduct  of  Fallopius, 


THE  BONES  OF  THE  HEAD  73 

and  transmits  the  external  superficial  petrosal  nerve.  This  latter, 
however,  with  the  nerve,  is  inconstant.  Another  small  groove 
marks  the  upper  wall  of  the  canal  for  the  tensor  tympani  muscle  at 
the  petro-squamous  angle,  and  leads  backwards  and  outwards, 
parallel  with  the  preceding  groove,  to  a  minute  foramen,  situated  a 
little  external  to  the  hiatus  Fallopii,  called  the  accessory  hiatus, 
which  transmits  the  small  superficial  petrosal  nerve.  Behind  and 
external  to  the  hiatus  Fallopii  is  an  elevation,  called  the  eminentia 
arcuata,  which  coincides  with  the  position  of  the  superior  semi- 
circular canal  of  the  internal  ear.  Between  this  eminence  and  the 
hiatus  Fallopii  internallj^  and  the  petro-squamous  fissure  externally 
there  is  a  plate  of  bone,  called  the  tegmen  tympani,  which  forms  the 
roof  of  the  tympanic  cavity  and  of  the  canal  for  the  tensor  tympani 
muscle. 

The  posterior  surface,  which  looks  backwards  and  inwards,  forms 
part  of  the  posterior  cranial  fossa.  It  presents  about  its  centre  a 
large  opening,  which  leads  into  a  short  canal,  called  the  internal 
auditory  meatus,  for  the  passage  of  the  facial  and  auditory  nerves, 
the  pars  intermedia  of  Wrisberg,  and  the  auditory  artery.  At  the 
deep  end  of  this  meatus  there  is  a  perforated  plate  of  bone,  known 
as  the  lamina  cribrosa,  which  is  divided  into  an  upper  and  a 
lower  fossa  by  a  transverse  ridge,  called  the  falciform  crest.  The 
upper  fossa  presents  at  its  anterior  part  a  special  foramen  which 
leads  into  the  aqueduct  of  Fallopius,  and  by  this  foramen  the  facial 
nerve  leaves  the  meatus.  The  remainder  of  the  upper  fossa  is  known 
as  the  superior  vestibular  area,  and  it  is  pierced  by  the  nerves  and 
arteries  destined  for  the  utricle  and  the  ampullae  of  the  superior  and 
external  semicircular  canals.  The  lower  fossa  contains  the  cochlear 
area,  which  is  pierced  by  the  cochlear  nerves  and  arteries,  the 
inferior  vestibular  area  for  the  nerves  and  arteries  to  the  saccule, 
and  the  foramen  singulare  for  the  nerves  and  arteries  to  the  ampulla 
of  the  posterior  semicircular  canal.  The  aqueduct  of  Fallopius, 
for  the  facial  nerve,  extends  from  the  deep  end  of  the  internal 
auditory  meatus  to  the  stylo-mastoid  foramen,  between  which 
points  it  takes  a  very  circuitous  course.  It  passes  at  first 
horizontally  outwards  between  the  cochlea  and  vestibule  to  the 
inner  wall  of  the  tympanum,  then  it  bends  sharply  backwards, 
lying  above  the  fenestra  ovalis,  and  finally,  making  another 
abrupt  bend,  it  descends  in  the  angle  between  the  inner  and 
posterior  walls  of  the  tympanum  to  the  stylo-mastoid  foramen. 
The  hiatus  Fallopii  leads  from  the  commencement  of  the  aqueduct 
to  the  superior  surface  of  the  petrous  portion,  and,  as  stated, 
transmits  the  great  superficial  petrosal  nerve.  The  aqueduct,  as 
it  descends  behind  the  tympanum,  communicates  with  the  canal 
of  the  pyramid  by  an  opening  through  which  the  nerve  to  the 
stapedius  reaches  that  muscle,  and  below  the  pyramid  it  presents 
another  oj)ening,  called  the  iter  chordae  posterius,  by  which  the 
chorda  tympani  nerve  ])asses  into  tlie  tympanum. 

About  \  inch  external  to  the  opening  of  the  internal  auditory 


74 


A  MANUAL  OF  ANATOMY 


meatus  there  is  a  narrow  fissure,  overhung  by  a  thin  scale  of  bone, 
called  the  aqueductus  vestibuli,  which  contains  a  small  artery  and 
vein,  and  the  ductus  endolymphaticus .  Close  to  the  superior  border, 
about  midway  between  the  opening  of  the  internal  auditory  meatus 
and  the  aqueductus  vestibuli,  there  is  a  depression  containing  a 
small  opening,  known  as  the  hiatus  subarcuatus,  which  represents 
the  floccular  fossa  of  early  life. 

The  inferior  surface  appears  on  the  exterior  of  the  base  of  the 
skull.  Near  the  apex  there  is  a  large  rough  surface  which  gives 
origin  to  fibres  of  the  levator  palati,  and  behind  this  a  circular 
opening,  called  the  carotid  foramen,  which  is  the  inlet  to  the  carotid 


Mastoid 
Antrum 


Pyramid,  with  Opening  for  Stapedius 

Fenestra  Ovale 
Aqueduct  of  Fallopius  at  Hiatus  Fallopii      ; 

Gasserian  Depression 


Outlet  of  Carotid  Canal 


Mastoid  Cells 


Promontory 
Fenestra  Rotunda 

Sinus  Tympani 


Outlet  of  Aqueduct  of  Fallopius 
at  Stylo-mastoid  Foramen 


Fig.   50. — Section  through  the  Petrous  and  Mastoid  Portions  of  the 
Temporal  Bone,   showing  the  Tympanum   and   Mastoid   Cells. 


canal.  This  canal,  which  transmits  the  internal  carotid  artery 
and  the  carotid  sympathetic  plexus,  passes  at  first  vertically 
upwards,  and  then,  bending  at  a  right  angle,  it  passes  horizontally 
forwards  and  inwards,  to  open  at  the  apex,  below  the  Gasserian 
depression,  into  the  foramen  lacerum  medium.  On  the  posterior 
wall  of  the  vertical  portion  of  the  canal  is  a  minute  foramen  for  the 
tympanic  branch  of  the  carotid  sympathetic  plexus  and  tympanic 
branch  of  the  internal  carotid  artery.  Behind  the  carotid  foramen 
is  the  jugular  fossa,  which,  with  the  jugular  notch  of  the  occipital, 
forms  the  jugular  foramen.  On  the  outer  wall  of  this  fossa,  near 
the  root  of  the  styloid  process,  there  is  the  opening  of  the  auricular 
canaliculus  for  the  auricular  branch  (Arnold's  nerve)  of  the  pneumo- 
gastric.     On  the  carotid  ridge,  between  the  carotid  foramen  and 


THE  BONES  OF  THE  HEAD 


75 


the  jugular  fossa,  is  the  opennig  of  the  tympanic  canaliculus  for  the 
tympanic  branch  (Jacobson's  nerve)  of  the  glosso-pharyngeal  and 
the  tympanic  branch  of  the  ascending  pharyngeal  artery.  Behind 
the  jugular  fossa,  internal  to  the  stylo-mastoid  foramen,  is  the 
rough  jugular  facet  for  articulation  with  the  extremity  of  the 
jugular  process  of  the  occipital,  by  synchondrosis  up  to  the 
twenty-fifth  year,  after  which  ankylosis  takes  place.  External 
to   the  jugular   facet   is  the  styloid  process,  immediately  behind 

Squamous  Portion 


Orifice  of  Eustachian  Canal 

Surface  for  Levator  Palati 
i 

Outlet  of  Carotid  Canal 


Zygoma  — 

Surf,  for  Zygom.  Fossa   - 
Eminentia  Articularis   - 

Ant.  Part  of  Glen.  Fossa     — 

Fissure  of  Glaser 

Post.  Part  of  Glen.  Fossa'     

Ext.  Aud.  Process     

Stylo-mastoid  Foramen 

Mastoid  Process 1 

Digastric  Groove  \ 

Occipital  Groove 


Ape.\  of  Petrous  Portion 
I        I 


^Groove  for  Inf.  Petr.  Sinus 
Carotid  Foramen 
^^Aqueductus  Cochlea; 

>,  '^s     For.  for  Tymp.  Sympalh.  Nerve 
\    \Tvmpanic  Canaliculus 

ugular  Fossa 
Auricular  Canaliculus 

Jugular  Facet 


Styloid  Process 


'  Tympanic  Plate 

Fig.  51. — The  Right  Temporal  Bone  (Inferior  View). 


the  root  of  which  is  the  stylo-mastoid  foramen.  This  foramen 
is  the  outlet  of  the  aqueduct  of  Fallopius,  and  by  it  the  facial 
nerve  makes  its  exit,  whilst  the  stylo-mastoid  branch  of  the 
posterior  auricular  artery  passes  in.  A  little  behind  the  stylo- 
mastoid foramen,  between  the  mastoid  process  and  tympanic 
plate,  is  the  auricular  or  tympano-mastoid  fissure  for  the  exit  of 
Arnold's  nerve. 

The   anterior   or   tympanic   surface,   which    is   concealed  by  the 
tympanic    plate,    looks    into    the    tympanic    cavity,    of    which    it 


76  A  MANUAL  OF  ANATOMY 

forms  the  posterior  and  inner  walls,  and  it  presents  the  mastoid 
antrum. 

The  borders  are  anterior,  superior,  posterior,  and  inferior.  The 
anterior  border  separates  the  superior  from  the  anterior  or  tympanic 
surface.  It  is  very  short,  and  forms  an  acute  angle  with  the 
squamous  portion,  within  which  the  posterior  pointed  extremity 
of  the  great  wing  of  the  sphenoid  is  received.  This  angle  presents 
an  opening,  called  the  Eustachian  orifice,  and  the  canal  to  which 
it  leads  is  divided  into  two  compartments  by  a  thin  transverse 
shelf  of  bone,  scooped  out  on  its  under  surface,  called  the  processus 
cochleariformis.  The  upper  small  compartment  lodgas  the  tensor 
tympani  muscle,  and  the  lower  large  one  forms  the  osseous 
part  of  the  Eustachian  tube.  Both  of  these  canals  lead  upwards 
and  backwards  to  the  anterior  part  of  the  tympanic  cavity. 
The  superior  border,  which  is  the  longest,  separates  the  superior 
from  the  posterior  surface.  It  gives  attachment  to  the  tentorium 
cerebelli,  and  is  grooved  for  the  superior  petrosal  venous  sinus. 
The  inner  part  of  this  border  frequently  presents  a  process,  which 
projects  over  the  upper  end  of  the  groove  for  the  inferior  petrosal 
venous  sinus,  and  gives  attachment  to  the  petro-sphenoidal  ligament. 
This  ligament  connects  it  with  the  lateral  border  of  the  dorsum 
sellce  of  the  sphenoid  (which  may  present  a  superior  petrosal 
process),  and,  if  it  ossifies,  it  bridges  over  a  foramen  through 
which  the  inferior  petrosal  sinus  and  sixth  cranial  nerve  pass. 
The  posterior  border  separates  the  posterior  from  the  inferior 
surface.  Its  outer  part,  opposite  the  jugular  fossa,  enters  into  the 
formation  of  the  jugular  foramen,  and  its  inner  part  presents  a 
groove  for  the  inferior  petrosal  sinus,  and  articulates  with  the  side 
of  the  basilar  portion  of  the  occipital.  In  line  with  the  opening 
of  the  internal  auditory  meatus  it  presents  a  triangular  depression, 
which  encroaches  on  the  inferior  surface  and  leads  to  a  small  canal, 
called  the  aqueduetus  cochleae.  This  aqueduct  transmits  a  smsd] 
vein  from  the  cochlea  to  the  inferior  petrosal  sinus,  and  also  a  com- 
munication between  the  perilymph  of  the  scala  tympani  and  the 
subarachnoid  space,  sometimes  called  the  ductus  perilymphaticus. 
The  inferior  border  separates  the  inferior  from  the  anterior  surface, 
and  coincides  with  the  line  of  contact  of  the  tympanic  plate  with 
the  petrous  portion. 

The  apex  of  the  petrous  portion  presents  on  its  anterior  aspect 
the  Gasserian  depression  superiorly,  and  the  outlet  of  the  carotid 
canal  interiorly. 

The  base  is  the  part  of  the  petrous  portion  which  appears  on 
the  external  surface,  and  it  presents  a  large  opening  leading  into 
the  external  auditory  meatus.  This  opening  is  oval,  its  long  axis 
lying  vertically,  and  it  is  bounded  above  by  the  posterior  root  of  the 
zygoma,  whilst  the  remainder  of  its  circumference  is  formed  mainly 
by  the  external  auditory  process  of  the  tympanic  plate.  The  external 
auditory  meatus  is  formed  chiefly  by  the  tympanic  and  squamous 
portions,  but  also  slightly  by  the  mastoid  portion.     Its  direction 


THE  BONES  OF  THE  HEAD  77 

is  inwards,  slightly  forwards,  and  finally  downwards,  its  length  being 
rather  more  than  i  inch  (14  millimetres).  It  leads  to  the  tympanum, 
and  its  deep  end,  which  is  nearly  circular,  is  closed  by  the  membrana 
tympani.  This  membrane  is  placed  obliquely,  and  form?  an  acute 
angle  with  the  lower  wall  and  an  obtuse  angle  with  the  upper, 
so  that  the  floor  of  the  meatus  is  longer  than  the  roof,  the  anterior 
wall  being  also  longer  than  the  posterior.  Its  floor  presents  a 
slight  elevation  at  the  centre,  where  the  passage  is  narrower  than 
elsewhere,  this  portion  being  called  the  isthmus. 

The  tympanic  plate  is  situated  behind  the  fissure  of  Glaser,  and 
is  quadrilateral.  It  presents  two  surfaces  and  four  borders.  The 
external  surface  forms  the  posterior  part  of  the  glenoid  fossa,  and 
lodges  the  deep  portion  of  the  parotid  gland.  The  internal  surface 
forms  the  anterior,  inferior,  and  part  of  the  posterior,  walls  of  the 
external  auditory  meatus,  and  the  anterior  and  inferior  walls  of 
the  tympanum,  and  at  its  inner  or  deep  end  it  presents  a  groove, 
deficient  above,  for  the  membrana  tympani,  called  the  sulcus  tym- 
panicus.  The  outer  border  forms  the  external  auditory  process,  and 
is  curved  and  rough  for  the  cartilage  of  the  pinna.  The  inner  border 
is  situated  immediately  outside  the  bony  part  of  the  Eustachian 
tube,  and  is  short  and  irregular.  The  upper  border  bounds  the 
fissure  of  Glaser  posteriorly,  and  the  lower  border  forms  at  its 
back  part  the  vaginal  process,  which  ensheathes  the  base  of  the 
styloid  process  externally.  The  tympanic  plate  sometimes  presents 
a  small  opening  at  its  centre,  called  the  foramen  of  Buschke. 

The  styloid  process,  which  is  cyHndrical  and  tapering,  starts 
from  a  point  immediately  in  front  of  the  stylo-mastoid  foramen, 
and  is  directed  downwards  and  inwards.  The  muscular  and 
ligamentous  relations  of  the  process  are  as  follows  :  The  stylo- 
pharyngeus  muscle  arises  from  the  inner  aspect  of  the  base  ;  the 
stylo-hyoid  muscle  from  the  posterior  and  outer  aspect  of  the 
process  near  its  base  ;  the  stylo-glossus  muscle  from  the  front  of 
the  process  near  its  tip  ;  the  stylo-mandibular  ligament  is  attached 
to  it  just  below  the  stylo-glossus  ;  and  the  stylo-hyoid  ligament  is 
attached  exactly  to  the  tip. 

The  blood-supply  of  the  bone  is  chiefly  derived  from  the 
following  sources  :  The  squamous  portion  receives  externally 
branches  from  the  anterior  and  posterior  deep  temporal  arteries 
of  the  internal  maxDlary,  and  internally  branches  of  the  middle 
meningeal.  Other  arterial  twigs  enter  the  bone  at  definite  points, 
as  follows  :  internal  auditory  from  the  basilar,  through  the  internal 
auditory  meatus ;  petrosal  from  the  middle  meningeal ,  through  the 
hiatus  Fallopii ;  stylo-mastoid  from  the  posterior  auricular,  through 
the  stylo-mastoid  foramen  ;  tympanic  from  the  internal  maxillary, 
through  the  Glaserian  fissure ;  tympanic  from  the  ascending 
pharyngeal,  through  the  tympanic  canaliculus ;  tympanic  from 
thf  internal  carotid,  through  the  foramen  on  the  posterior  wall 
of  the  vertical  portion  of  the  carotid  canal ;  the  mastoid  from  the 
occipital,  through  the  arterial  fissure  on  the  outer  surface  of  the 


78  A   MANUAL  OF  ANATOMY 

mastoid  process ;  and  twigs  from  the  mastoid  division  of  the 
posterior  auricular,  through  the  foramina  on  the  outer  surface  of 
the  mastoid  portion. 

Articulations. — ^These  are  usually  five  in  number,  as  follows  : 
posteriorly  and  internally  with  the  occipital,  superiorly  with  the 
parietal,  anteriorly  with  the  sphenoid  and  malar,  and  externally 
with  the  condyle  of  the  inferior  maxilla,  the  latter  being  a  movable 
articulation.  Sometimes  the  temporal  articulates  with  the  frontal, 
giving  rise  to  a  fronto-squamosal  suture. 

Structure. — The  squamous  portion  is  thin,  and  is  practically 
composed  of  two  plates  of  compact  bone.  The  mastoid  portion 
is  thick,  and,  as  stated,  contains  the  mastoid  antrum  and  mastoid 
cells.  The  petrous  portion  is  remarkable  for  its  hardness,  and  it 
contains  all  the  divisions  of  the  organ  of  hearing,  except  the  carti- 
laginous pinna  on  the  outer  side  of  the  head.  Thus  it  contains 
(i)  the  osseous  external  auditory  meatus;  (2)  the  tympanum  or 
middle  ear,  with  its  three  ossicles,  malleus,  incus,  and  stapes,  etc. ; 
and  (3)  the  osseous  labyrinth  or  internal  ear,  which  contains  the 
membranous  labyrinth,  consisting  of  the  utricle,  saccule,  semicircular 
canals,  and  membranous  cochlea.  It  also  contains,  for  a  certain 
distance,  extensions  of  the  mastoid  cells. 

Varieties. — (i)  Foramen  of  Huschke  in  the  centre  of  the  tympanic  plate,  due 
to  imperfect  ossification.  (2)  Absence  of  petro-squamous  suture.  (3)  Absence 
of  the  foramen  within  the  hiatus  Fallopii  for  the  external  superficial  petrosal 
nerve. 

Ossification. — The  temporal  bone  is  developed  in  three  parts,  namely, 
squamosal,  tympanic,  and  petrosal.  The  squamosal  and  tympanic  elements 
are  formed  in  'membrane,  and  the  petrosal  in  cartilage.  The  squamosal  gives 
rise  to  the  squamo-zygomatic  portion,  and  the  upper  and  front  part  of  the 
mastoid  portion  ;  the  tympanic  forms  the  tympanic  annulus  ;  and  from  the 
petrosal  are  developed  the  petrous  portion  and  the  greater  part  of  the  mastoid 
portion.  It  is  to  be  noted  that  the  mastoid  portion  is  not  an  independent 
part  developmentally,  but  belongs  chiefly  to  the  petrous  and  partly  to  the 
squamosal  portions.  The  centre  for  the  squamosal  appears  towards  the  end 
of  the  second  month  of  intra-uterine  life  in  the  region  of  the  root  of  the  zygoma, 
and  from  this  ossification  extends  upwards  into  the  squamosal,  forwards  into 
the  zygoma,  and  inwards  into  the  glenoid  fossa  in  front  of  the  Glaserian 
fissure.  From  the  posterior  part  of  the  squamosal  a  downward  growth  of 
bone  takes  place  below  the  supramastoid  crest,  called  the  postauditory  process, 
which  forms  the  outer  wall  of  the  mastoid  antrum,  and  gives  rise  to  the  upper 
and  front  part  of  the  mastoid  portion.  The  centre  for  the  tympanic  element 
appears  towards  the  end  of  the  third  month  of  intra-uterine  life  in  the  lower 
part  of  the  external  membranous  wall  of  the  tympanum,  and  from  this  is 
developed  the  tympanic  annulus.  This  ring  forms  about  five-sixths  of  a 
circle,  the  deficiency  being  above,  where  it  is  closed  by  the  squamosal,  and 
within  the  circumference  of  the  ring  there  is  a  groove  for  the  membrana 
tympani.  Previous  to  birth  the  extremities  of  the  ring  become  ankylosed 
to  the  squamosal,  and  the  tympanic  plate  is  formed  by  an  outward  growth 
from  it,  so  that  it  is  ultimately  located  at  the  deep  end  of  the  external  auditory 
meatus.  The  petrosal  element  or  periotic  cartilaginous  capsule  is  developed 
from  four  centres,  which  appear  towards  the  end  of  the  fifth  month,  and  from 
which  ossification  proceeds  rapidly,  union  between  the  four  centres  being 
effected  by  the  end  of  the  sixth  m,onth  of  intra-uterine  life.  These  centres 
are  called  opisthotic,  pro-otic,  pterotic,  and  epiotic,  in  the  order  of  their  appear- 


THE  BONES  OF  THE  HEAD 


79 


ance.  The  opisthotic  centre  appears  on  the  promontory  on  the  inner  wall  of 
the  tympanum,  from  which  point  ossification  extends  downwards  around  the 
fenestra  rotunda,  and  forms  (i)  the  floor  of  the  vestibule,  (2)  the  lower  part 
of  the  fenestra  ovalis,  (3)  the  floor  of  the  internal  auditory  meatus,  (4)  the 
greater  part  of  the  bony  investment  of  the  cochlea,  (5)  the  carotid  canal, 
and  (6)  the  floor  of  the  tympanum.  The  pro-otie  centre  appears  near  the  inner 
limb  of  the  superior  semicircular  canal  in  the  region  of  the  eminentia  arcuata, 
and  from  it  are  formed  (i)  the  bony  investment  of  the  superior  semicircular 


S(iuani.-Zyg.  Portion 


Internal  Auditory  Meatus 

^'5 


Fenestra  Ovalis 


Fig. 


rympanic  Annulus 

^Floccular  Fossa 
,Aqueductus  Vestibuli 

-Aqueductus  Cochlea; 

Squam.-Zyg.  Portion 


_.  Petrosal  Portion 
(Petro-Mastoid) 


.Pyramid,  with  opening  for 

_,  .  Stapedius 

inus  1  ympani 

stra  Rotunda 


/  ^.'I'ympanic  Annulus 

Promontory 

The  Temporal  Bone  in  Early  Life. 


A,  Squamo-Zygomatic  Portion  and  Tympanic  Annulus ;    B,  Petrosal  Portion  ; 
C,  The  Bone  at  Birth. 


canal,  (2)  the  roof  of  the  vestibule,  (3)  tlie  roof  of  the  cochlea,  (4)  the  roof  of 
the  internal  auditory  meatus,  (5)  tiie  upper  part  of  the  fenestra  ovalis,  and 
(6)  the  upper  and  inner  part  of  the  mastoid  portion.  The  pterotic  centre  (Bland- 
Sutton)  appears  over  the  outer  liml)  of  the  external  semicircular  canal,  and 
from  it  are  formed  (i)  th'j  coverin'.<  of  the  external  semicircular  canal,  and 
(2)  the  tegmen  tympani.  The  epiotic  centre,  sometimes  double,  appears  in 
the  region  of  the  back  part  of  the  posterior  semicircular  canal,  and  from  it  the 
lower  pari  of  the  mastoid  is  formed,  as  well  as  the  investment  of  the  ])osterior 
semicircular  canal.  At  the  period  of  birth  (the  tympanic  having  previously 
joined  the  squamosal)  the  temporal  bone  is  composed  of  two  parts — (i )  a  united 


8o  A  MANUAL  OF  ANATOMY 

squamo-zygomatic  and  tympanic,  and  (2)  a  petrosal,  a  plate  of  cartilage  inter- 
vening, and  these  unite  in  the  course  of  the  first  year.  At  birth  the  bone  is  of 
loose  consistence,  the  mastoid  portion  is  flat,  the  external  auditory  meatus  is  un- 
developed, the  tympanic  annulus  and  membrana  tympani  are  on  a  level  with 
the  exterior  of  the  bone,  the  glenoid  and  jugular  fossse  are  shallow,  the  floccular 
fossa  is  conspicuous,  and  the  hiatus  Fallopii  is  an  open  groove.  The  tympanic 
plate  now  becomes  formed  in  fibrous  tissue,  by  the  extension  of  osseous  matter 
outwards  from  two  tubercles  on  the  anterior  and  posterior  parts  of  the  outer 
aspect  of  the  tympanic  annulus  superiorly.  As  these  tubercles  grow,  they 
meet  and  enclose  an  opening  in  the  floor  of  the  external  auditory  meatus, 
which  usually  becomes  closed  before  the  period  of  puberty,  but  it  may  persist 
throughout  life  as  the  foramen  of  Huschke.  The  mastoid  antrum  is  present  at 
birth,  and  is  of  large  proportionate  size,  its  outer  wall  being  very  thin.  The 
mastoid  process  becomes  developed  in  the  course  of  the  second  year,  and  the 
antrum  becomes  relatively  smaller,  its  outer  wall  at  the  same  time  becoming 
thicker.  The  mastoid  cells  do  not  appear  until  the  approach  of  the  period  of 
puberty. 

Styloid  Process. — This  process  is  developed  separately  from  the  upper  end 
of  the  cartilage  of  the  second  visceral  arch.  It  has  two  centres  of  ossification, 
one  for  the  tympano-hyal  or  basal  part  appearing  before  birth,  which  soon 
joins  the  rest  of  the  bone,  and  the  other  for  the  stylo-hyal  appearing  in 
the  second  year.  The  latter  portion  does  not  attain  marked  development 
until  after  puberty,  and  its  union  with  the  tympano-hyal  usually  takes  place 
in  adult  life,  but  it  sometimes  persists  in  an  independent  condition. 


The  Sphenoid  Bone. 

The  sphenoid  bone  is  so  named  from  the  wedge-like  position 
which  it  occupies  in  the  base  of  the  skull,  where  it  lies  with  its 
long  axis  placed  transversely.  It  enters  into  the  formation  of  the 
anterior,  middle,  and  posterior,  fossae  of  the  base,  the  temporal 
and  nasal  fossae,  and  the  orbits.  It  consists  of  a  central  portion 
or  body,  two  great  wings,  two  small  wings,  and  two  pterygoid 
processes. 

The  body  presents  six  surfaces — superior,  inferior,  anterior, 
posterior,  and  two  lateral,  one  at  either  side.  Within  the  body 
are  two  large  cavities,  called  the  sphenoidal  air  sinuses,  each  of 
which  opens  on  the  anterior  surface  by  a  small  circular  aperture. 

The  superior  surface  presents  at  its  centre  a  depression,  called 
the  sella  turcica  or  pituitary  fossa,  for  the  pituitary  body  or  hypo- 
physis cerebri,  and  in  the  foetus  it  is  pierced  by  the  superior  opening 
of  the  cranio-pharyngeal  canal.  In  front  of  the  sella  turcica  is 
the  oliviary  eminence,  which  indicates  the  place  of  junction  of  the 
presphenoid  and  postsphenoid  portions,  and  anterior  to  this  is 
a  transverse  furrow,  called  the  optic  groove,  both  of  which  support 
the  optic  commissure  or  chiasma.  The  groove  leads  at  either  side 
to  the  optic  foramen,  by  which  the  optic  nerve  leaves  the  crariial 
cavity,  and  anteriorly  it  is  limited  by  a  transverse  ridge,  called 
the  limbus  sphenoidalis.  In  front  of  the  limbus  (border)  is  a  smooth 
elevated  platform,  called  the  jugum  sphenoidale,  which  is  con- 
tinuous laterally  with  the  superior  surface  of  the  small  wing,  and 
presents  at  either  side  the  olfactory  groove  for  the  olfactory  bulb. 
The  anterior  border  of  the  jugum  is  projected  in  the  middle  line 
into   the   ethmoidal   spine,   which   articulates  with   the   posterior 


THE  BONES  OF  THE  HEAD  8i 

margin  of  the  cribriform  plate  of  the  ethmoid.  The  sella  turcica 
is  bounded  posteriorly  by  a  prominent  quadrilateral  plate  of  bone, 
called  the  dorsum  sellse  or  dorsum  ephippii  (back  of  the  saddle), 
which  is  directed  forwards  and  upwards.  The  antero-inferior 
surface  of  this  plate  overhangs  the  sella  turcica,  and  the  postero- 
superior  surface,  called  the  clivus  (slope),  is  inclined  downwards 
and  backwards  to  become  continuous  with  the  basilar  groove  of 
the  occipital.  The  clivus  lodges  the  upper  part  of  the  pons  Varolii 
and  the  basilar  artery.  The  antero-superior  border  of  the  dorsum 
sellae  presents  at  either  side  the  posterior  clinoid  process  for  a  portion 


Jugum  Sphenoidale 

Limbus  Sphenoidalis 
Mid.  Clinoid  Process  <^ 

Optic  Foramen       \         \ 
Ant.  Clinoid  Process        \      •,  >^ 

Sphenoidal  Fissure        \       "•       \         \ 


Ethmoidal 
Spine     Optic  Groove 


Olfactory  Groove 

Olivary  Eminence 

/  Carotid  Notch 
•     Small  Wing 
■     '      .'      Sylvian  Border  of  Small  Wing 
.■■     /      ■        ,  Great  Wing 


Foram.  Rotundum 


Foramen  Vesalu 
Foramen  Ovale - 

P'oram.  Spinosum  - 


Canaliculus  Innominatus 

Lingula 
Cavernous  Groove 
Post.  Clinoid  Proces; 


\        Spinous  Process 
\ 
Notch  for  6th  Cranial  Nerve 

Posterior  Petrosal  Process 
Clivus  ;      Dorsum  Sella; 
.Sella  Turcica 


Fig.   53. — The  Sphenoid  Bone  (Superior  View). 


ot  the  tentorium  cerebelli  and  the  interclinoid  ligament,  which 
latter  connects  it  with  the  anterior  clinoid  process,  and  is  some- 
times ossified.  On  each  lateral  border  of  the  dorsum  sellae,  a  little 
below  the  posterior  clinoid  process,  is  a  notch,  which  transmits  the 
sixth  cranial  nerve.  At  the  lower  end  of  each  lateral  border  there  is 
a  projection,  called  the  posterior  petrosal  process,  which  aiticulates 
with  the  apex  of  the  petrous  portion  of  the  temj)oral,  and  bounds 
internally  the  foramen  lacerum  medium. 

The  inferior  surface  of  the  body  is  limited  at  either  side  by 
the  internal  pterygoid  plate  of  the  pterygoid  process.  In  the 
middle  line  it  presents  a  vertical,  antero-posterior  ridge,  called 

6 


82  A  MANUAL  OF  ANATOMY 

the  rostrum,  which  is  continuous  with  the  sphenoidal  crest  on  the 
anterior  surface,  and  is  received  into  the  cleft  between  the  alee 
of  the  vomer.  At  either  side  of  the  rostrum  there  is  a  thin  scale 
of  bone  projecting  inwards  for  a  short  distance  from  the  root  of 
the  internal  pterygoid  plate,  called  the  vaginal  process,  which 
articulates  with  the  ala  on  the  upper  border  of  the  vomer,  and 
with  it  covers  the  greater  part  of  the  inferior  surface  of  the  body 
at  either  side  of  the  middle  line.  On  the  inferior  surface  of  this 
process  there  is  a  groove,  which  is  converted  by  the  sphenoidal 
process  of  the  palate  bone  into  a  canal,  called  the  pterygo-palatine 
canal,  for  the  passage  of  the  pharyngeal  nerve  and  pterygo-palatine 
artery. 

The  anterior  surface  presents  in  the  middle  line  a  vertical  ridge, 
continuous  above  with  the  ethmoidal  spine  and  below  with  the 
rostrum,  called  the  sphenoidal  crest,  which  articulates  with  the 
perpendicular  plate  of  the  ethmoid  and  forms  part  of  the  nasal 
septum.  On  either  side  of  this  crest  the  surface  is  divided  into 
two  parts,  outer  and  inner.  The  outer  part  is  rough,  and  articulates 
with  the  back  part  of  the  lateral  mass  of  the  ethmoid  and  the  orbital 
process  of  the  palate  bone.  The  inner  part  presents  the  opening  of 
the  sphenoidal  air  sinus  of  its  own  side,  with  the  margins  of  which 
he  sphenoidal  turbinate  or  spongy  bone  articulates.  When  this 
bone  is  in  position  the  opening  of  the  sinus  is  small  and  circular, 
and  is  placed  superiorly,  but  when  the  bone  has  been  removed 
the  opening  is  of  large  size  and  irregular  outline.  It  communi- 
cates anteriorly  with  the  spheno-ethmoidal  recess  of  the  nasal 
fossa  above  and  behind  the  superior  meatus.  The  part  of  the 
anterior  surface  which  presents  the  opening  of  the  sphenoidal 
air  sinus  enters  into  the  formation  of  the  roof  of  the  corresponding 
nasal  fossa. 

The  posterior  surface  is  rough  and  truncated.  It  articulates 
with  the  basilar  process  of  the  occipital  by  synchondrosis  up  to 
the  twentieth  year,  after  which  ankylosis  takes  place. 

The  lateral  sitrface  gives  attachment  to  the  great  wing  and  a 
portion  of  the  small  wing.  Anteriorly,  beneath  the  small  wing,  it 
forms  the  inner  boundary  of  the  sphenoidal  fissure  and  the  back 
part  of  the  inner  wall  of  the  orbit.  Above  the  attachment  of  the 
great  wing  it  presents  a  winding  groove,  called  the  cavernous  or 
carotid  groove,  which  contains  the  cavernous  venous  sinus  and 
the  internal  carotid  artery.  The  direction  of  this  groove  is  from 
behind  forwards,  and  its  deepest  part  is  placed  posteriorly,  where 
it  is  bounded  internally  by  the  posterior  petrosal  process,  and 
externally  by  the  lingula  sphenoidalis  or  anterior  petrosal  process. 
This  latter  process  is  a  sharp  scale  of  bone  which  projects  back- 
wards in  the  angle  between  the  great  wing  and  body. 

The  small  or  orbital  wings  (orbito-sphenoids)  extend  almost 
horizontally  outwards  on  a  level  with  the  anterior  part  of 
the  upper  surface  of  the  body.  Each  arises  by  two  roots — an 
upper,  which  is  expanded  and  compressed  from  above  downwards. 


THE  BONES  OF  THE  HEAD 


83 


and  is  on  a  level  with  the  anterior  part  of  the  upper  surface  of  the 
body ;  and  a  bwer,  slender  and  compressed  from  before  backwards, 
which  arises  from  the  anterior  part  of  the  side  of  the  body.  The 
wing  is  triangular  and  flattened  from  above  downwards.  The 
superior  surface,  smooth  and  somewhat  concave,  forms  the  back 
part  of  the  anterior  cranial  fossa.  The  inferior  surface  overhangs 
the  sphenoidal  fissure,  and  forms  the  back  part  of  the  roof  of  the 
orbit.  Externally  the  wing  ends  in  a  slender,  pointed  extremity, 
which  lies  very  near  the  great  wing,  but  does  not  as  a  rule  touch 


Opening  of  Sphenoidal  Sinus 

Sphenoidal  Fissure 

Temp.  Div.  of  Ext.         For  Ext.  Ang. 
Surf,  of  Great  Wing      Proc.  of  Frontal   ■ 


fc^thmoidal  .Spine 

Optic  Foramen 


Orbital  Surface 
of  Great  Wing 


Vidian  Canal 


Zygom.  Div.  of  Ext.  ^' 
Surf,  of  Great  Wing 

.Spinous  Proces: 


External  Pterygoid  Plate 

Hamular  Process  / 

Internal  Pterygoid  Plate       ; 

Sphenoidal  Spongy  Bone' 

Vaginal  Process 


Foramen  Rotundum 

Sphen.-maxill.  Surf. 

of  Great  Wing 
.Sphenoidal  Crest 


^-  Pterygoid  Notch 
Pterygo-palatine  Groove 

Rostrum 


Fig.  54. — The  Sphenoid  Bone  (Anterior  View). 


it,  though  it  may  do  so.  The  anterior  border  is  thin  and  serrated 
for  the  orbital  plate  of  the  frontal.  The  posterior  border,  smooth, 
thick,  and  round,  corresponds  with  the  Sylvian  fissure  of  the 
cerebrum,  from  which  circumstance  it  is  known  as  the  Sylvian 
bordei".  It  forms  at  either  side  the  line  of  demarcation  between 
the  anterior  and  middle  cranial  fossae,  and  terminates  internally 
in  the  anterior  clinoid  process  for  a  portion  of  the  tentorium 
cerebelli  ;iiifl  iIh;  interclintjid  ligament. 

Between  the  anterior  clinoid  j^rocess  and  the  side  of  the  olivary 
eminence  is  the  semicircular  carotid  notch,  which  is  the  anterior 

6—2 


■84  A  MANUAL  OF  ANATOMY 

termination  of  the  carotid  groove,  and  lodges  the  internal  carotid 
artery. 

On  either  side  of  the  body,  close  to  the  inner  side  of  the  anterior 
extremity  of  the  carotid  groove  and  posterior  to  the  carotid  notch, 
opposite  the  anterior  clinoid  process,  there  is  usually  a  small 
tubercle,  called  the  middle  clinoid  process.  It  is  connected  with 
the  anterior  clinoid  process  by  the  carotico-clinoid  ligament,  which 
bridges  over  the  carotid  notch.  When  this  ligament  undergoes 
ossification  a  carotico-clinoid  foramen  is  formed,  through  which  the 
internal  carotid  artery  ascends  after  leaving  the  carotid  groove. 

In  front  of  the  carotid  notch,  between  the  upper  and  lower  roots 
of  the  small  wing,  there  is  a  circular  aperture,  called  the  optic 
foramen,  which  leads  forwards  and  outwards  into  the  orbit,  and 
transmits  the  optic  nerve  and  the  ophthalmic  artery. 

The  great  or  temporal  wings  (alisphenoids)  extend  outwards, 
upwards,  and  forwards  from  the  sides  of  the  body.  The  posterior 
part  of  each  projects  backwards,  and  ends  in  a  pointed  extremity, 
which  is  received  within  the  petro-squamous  angle  of  the  temporal 
bone.  From  this  extremity  a  sharp  projection  extends  downwards 
for  a  short  distance,  called  the  spinous  process  or  alar  spine,  which 
presents  a  groove  on  its  inner  aspect  for  the  chorda  tympani  nerve. 
Anterior  to  this  groove  and  encroaching  on  the  posterior  border 
of  the  great  wing  is  another  groove  for  the  cartilaginous  part  of 
the  Eustachian  tube.  The  spinous  process  gives  attachment  to 
(i)  the  spheno-mandibular  ligament,  (2)  some  fibres  of  the  tensor 
palati,  and  (3)  the  anterior  ligament  of  the  malleus,  or  band  of 
Meckel. 

Each  great  wing  presents  three  surfaces — superior,  antero- 
internal,  and  external  ;  and  four  borders — posterior,  external, 
anterior,  and  internal. 

The  iuper.'or  or  cerebral  surface,  which  at  its  front  part  rises 
almost  vertically  upwards,  is  concave,  and  enters  into  the  formation 
of  the  lateral  division  of  the  middle  cranial  fossa.  It  supports 
the  temporo-sphenoidal  lobe  of  the  cerebrum,  and  presents  a  few 
digitate  impressions,  whilst  externally  it  is  grooved  for  a  branch 
of  the  middle  meningeal  artery.  This  surface  presents  several 
important  foramina.  At  the  anterior  part  of  its  attachment  to 
the  side  of  the  body,  just  below  the  inner  end  of  the  sphenoidal 
fissure,  is  the  foramen  rotundum,  which  is  directed  from  behind 
forwards  and  transmits  the  superior  maxillary  division  of  the 
fifth  cranial  nerve.  A  little  behind  and  external  to  this  foramen 
is  the  foramen  ovale,  of  large  size  and  opening  vertically  down- 
wards, for  the  passage  of  the  inferior  maxillary  division  and  the 
motor  root  of  the  fifth  cranial  nerve,  the  small  meningeal  artery, 
an  emissary  vein  from  the  cavernous  sinus,  and  sometimes  the 
small  superficial  petrosal  nerve.  Internal  and  anterior  to  the 
foramen  ovale,  between  it  and  the  lingula  sphenoidalis,  there  is 
sometimes  a  small  opening,  called  the  foramen  Vesalii,  which 
leads   to   the   scaphoid   fossa   on   the   outer   side   of    the   root   of 


THE  BONES  OF  THE  HEAD  85 

the  internal  pterygoid  plate,  or  to  the  pterygoid  fossa  external  to 
the  scaphoid  fossa.  It  transmits  a  small  emissary  vein  from  the 
cavernous  sinus.  Behind  and  external  to  the  foramen  ovale  is  the 
small  circular  foramen  spinosum,  close  to  the  spinous  process,  which 
opens  vertically  downwards.  It  transmits  the  middle  meningeal 
artery  and  a  recurrent  branch  of  the  inferior  maxillary  nerve, 
and  is  sometimes  incomplete  }:)osteriorly.  Internal  to  this  foramen, 
between  it  and  the  foramen  ovale,  there  is  somet  mes  a  small 
opening,  called  the  canaliculus  innominatus,  for  the  small  superficial 
petrosal  nerve. 

The  antero  internal  surface  is  divisible  into  a  large  orbital  portion 
and  a  small  soheno-maxillary  portion.  The  orbital  division  is 
quadrilateral,  smooth,  and  slightly  concave,  and  it  forms  the  greater 
part  of  the  outer  wall  of  the  orbit.  The  sphen -^-maxillary  division 
is  situated  at  the  lower  and  inner  part  above  the  root  of  the 
pterygoid  process.  It  is  pierced  by  the  foramen  rotundum,  and 
lies  in  the  posterior  wall  of  the  spheno-maxiUary  fossa. 

The  external  or  teniporo-zygomatic  surface  is  elongated  from  above 
downwards,  and  is  continuous  with  the  outer  surface  of  the  external 
pterygoid  plate  of  the  pterygoid  process.  Towards  its  lower  part  it  is 
crossed  by  the  infratemporal  crest,  which  divides  it  into  a  large 
upper  and  a  small  lower  portion.  The  upper  or  temporal  division, 
which  is  directed  outwards,  forms  part  of  the  temporal  fossa,  and 
gives  origin  to  fibres  of  the  temporal  muscle.  The  lower  or 
zygomatic  division  looks  downwards  into  the  zygomatic  fossa,  and 
gives  origin  to  the  upper  head  of  the  external  pterygoid  muscle. 
At  its  lower  and  back  part  it  presents  the  openings  of  the  foramen 
ovale  and  foramen  spinosum. 

The  posterior  border  extends  from  the  spinous  process  to  the  body, 
passing  in  its  course  behind  the  foramen  ovale.  Over  its  inner 
two- thirds  it  bounds  the  foramen  lacerum  medium  anteriorly,  and 
over  its  outer  third,  where  it  becomes  serrated,  it  articulates  with 
the  petrous  portion  of  the  temporal,  the  two  forming  a  groove  for 
the  cartilaginous  part  of  the  Eustachian  tube.  The  external  border 
separates  the  superior  or  cerebral  from  the  external  or  temporo- 
zygomatic surface.  It  is  serrated  behind,  where  it  is  bevelled  at  the 
expense  of  the  upper  or  inner  plate,  but  in  front  it  is  squamous  and 
bevelled  at  the  expense  of  the  outer  plate.  The  entire  border 
articulates  with  the  squamous  portion  of  the  temporal.  The 
i.n'erior  border  or  malar  crest  scjiarates  the  orbital  and  temporal 
surfaces.  Its  direction  is  downwards  and  inwards,  and  it  is  sharp 
and  irregular  for  the  malar.  The  internal  border  is  situated  between 
the  orbital  and  cerebral  surfaces.  Its  direction  is  backwards  and 
inwards,  ard  it  forms  the  lower  boundary  of  the  sphenoidal  fissure. 
About  its  centre  it  presents  a  small  spine,  which  gives  origin  to 
fibres  of  the  lower  head  of  the  external  rectus  muscle  of  the  eye- 
ball. The  great  wing  antero-suj)eriorly  becomes  thick  and  expanded, 
and  it  here  presents  a  rough,  triangular,  serrated  surface  for  the 
frontal.     At  the  outer  end  of  this  surface   there  is  another  small 


86 


A   MANUAL  OF  ANATOMY 


triangular,  serrated  impression,  for  the  antero-inferior  angle  of  the 
parietal. 
The  sphenoidal  fissure,  also  called  the  foramen  lacerum  anterius 

or  orbitale,  is  situated  between  the  great  and  small  wings.  It  is 
triangular,  and  its  direction  is  inwards  and  downwards.  It  is 
bounded  above  by  the  small  wing,  below  by  the  internal  border  of 
the  great  wing,  and  internally  by  the  anterior  part  of  the  side  of  the 
body,  whilst  externally  it  is  closed  by  the  frontal^  or,  it  may  be,  the 
meeting  between  the  two  wings.  It  leads  from  the  middle  cranial 
fossa  to  the  orbit,  and  transmits  the  following  structures  :  the 
third  cranial  nerve,  the  fourth,  the  three  branches  of  the  ophthal- 
mic division  of  the  fifth  (namely,  frontal,  lachrymal,  and  nasal),  and 
the  sixth  cranial  nerves,  the  sympathetic  root  of  the  ciliary  ganglion, 


Posterior  Clinoid  Process 

Anterior  Clinoid  Process     1 

Post,  or  Sylvian  Border 
of  Small  Wing 


Dorsum  Sellse 

I  Back  Part  of  Carotid  Groove 

Sphenoidal  Fissure 


Ext.  Bord.  of  Great 
Wing,  for  Squam. 
Port,  of  Temporal 


Sup.  Surf,  of 
Great  Wing 


Spinous  Process'' 

Lingula/    ^^' 

Vidian  Canal  /    .- 
Scaphoid  Fossa 
Ext.  Pterygoid  Plate 


Groo\e  for  Chorda 
Tympani  Nerve 
^'Pterygoid  Tubercle 
^  Vaginal  Process 

Rostrum 

Pterygoid  Fossa 


Int.  Pterygoid  Plate'' 

Fig.   55. — The  Sphenoid  Bone  (Posterior  View). 


^  Pterygoid  Notch 
"^  Hamular  Process 


the  superior  and  inferior  ophthalmic  veins,  the  orbital  branch  of 
the  middle  meningeal  artery,  and  a  portion  of  the  dura  mater 
to  form  the  orbital  periosteum. 

The  pterygoid  processes  project  downwards  from  the  junction 
of  the  body  and  great  wings.  Each  is  composed  of  two  plates, 
external  and  internal,  united  in  front  to  form  a  thick  round 
border,  except  inferiorly,  where  they  are  separated  by  the 
pterygoid  notch,  which  receives  the  pyramidal  process  or  tuber- 
osity of  the  palate  bone.  At  the  upper  end  of  the  anterior 
border  a  triangular  surface  opens  out,  which  lies  in  the  posterior 
wall  of  the  spheno-maxillary  fossa,  and  presents  the  anterior  orifice 
of  the  Vidian  or  pterygoid  canal.  Posteriorly  the  two  plates  diverge, 
and  enclose  between  them  the  pterygoid  fossa,  which  contains 
the  internal  pterygoid  and  tensor  or  circumflexus  palati  muscles. 


THE  BONES  OF  THE  HEAD  87 

The  external  pterygoid  plate  is  broader  and  shorter  than  the 
internal,  and  is  directed  backwards  and  slightly  outwards.  Its 
outer  surface  looks  into  the  zygomatic  fossa,  and  gives  origin  to  the 
lower  head  of  the  external  pterygoid  muscle.  Its  inner  surface  looks 
into  the  pterygoid  fossa,  and  gives  origin  to  the  internal  pterygoid 
muscle.  The  posterior  border  usually  presents  towards  its  upper 
part  a  sharp  spine,  from  which  the  pterygo-spinous  ligament  extends 
backwards  and  outwards  to  the  spinous  process.  This  ligament 
sometimes  becomes  ossified,  and  a  foramen  is  then  formed,  called  the 
pterygo-spinous  foramen,  for  the  passage  of  muscular  branches  of 
the  inferior  maxillary  nerve.  Sometimes  there  is  another  spine 
towards  the  lower  end  of  this  border  for  another  pterygo-spinous 
ligament. 

The    internal    pterygoid    plate,    narrower   and   longer   than   the 
external,  is  prolonged  inferiorly  into  the  hamular  process,  which 
is  inclined  outwards,  its  outer  and  inferior  aspects  being  smooth 
and  grooved  for  the  play  of  the  tendon  of  the  tensor  or  circum- 
fie.vus   palati.     Superiorly  this   plate   is    inflected   as   the   vaginal 
process,  which  articulates  with  the  ala  of  the  vomer,  and  presents 
on  its  under  surface  a  groove  forming  part  of  the  pterygo-palatine 
canal    already   referred    to.     The    outer   surface    of    the    internal 
pterygoid  plate  looks  into  the  pterygoid  fossa,  and  is  related  to 
the  tensor  or  circumflexus  palati.     The  inner  surface  forms  the 
back    part    of  the  outer  wall   of  the  nasal  fossa.     The  posterior 
border  at  its   upper  end  presents  the   pterygoid  tubercle,  which 
has  the  posterior  end  of  the  Vidian  canal  above  and  external  to  it. 
Between  this  tubercle  and  the  Vidian  canal  on  the  one  hand,  and 
the  pterygoid   fossa  on   the   other,   is   the  scaphoid  fossa,  which 
gives  origin  to  the  tensor  or  circumflexus  palati.     On  the  posterior 
border  of  the  internal  pterygoid  plate,  below  the  lower  pointed 
end  of  the  scaphoid  fossa,  is  the   Eustachian  spine  or  processus 
tiihariiis,   which   supports   the   cartilage   of   the   Eustachian   tube. 
The  lower  third  of  the  posterior  border  and  the  hamular  process 
give  origin    to  fibres  of  the  superior  constrictor   muscle    of    the 
pharynx,  and  the  hamular  process  also  gives  attachment  to  the 
pterygo-mandibular  ligament.     The  anterior  border  articulates  with 
the  posterior  border  of  the  ]:)erpendicular  plate  of  the  palate  bone. 
The  Vidian  or  pterygoid  canal  pierces  the  bone  from  before  back- 
wards at  the  junction  of  the  internal  pterygoid  plate  and  body  on 
either  side.     Its  anterior  orifice  appears  on  the  posterior  wall  of  the 
spheno-maxillary  fossa,  below  and  internal  to  the  anterior  orifice 
of  the  foramen  rotundum,  and  posteriorly  it  opens  on  the  anterior 
wall  of  the  foramen  lacerum  medium,  above  and  external  to  the 
jjterygoid  tubercle.    It  gives  passage  to  the  Vidian  nerve  and  artery. 
Summary  of  Openings  in   the  Sphenoid   Bone.— (i)  Sphenoidal 
fissure,  between  small  and  great  wings  ;  (2)  optic  foramen,  between 
the  two  roots  of  the  small  wing ;  and,  in  the  great  wing   (3)  foramen 
rotundum  ;    (4)  foramen  ovale  ;    (5)  foramen  Vesalii  (inconstant)  ; 
(6)  foramen   spinosum  ;    (7)  canaliculus  innominatus  (inconstant)  ; 


88  A  MANUAL  OF  ANATOMY 

and  (8)  Vidian  or  pterygoid  canal,  the  last-named  being  between  the 
internal  pterygoid  plate  and  the  body.  All  these  openings  are 
common  to  each  side. 

The  sphenoidal  air  sinuses  are  situated  within  the  body,  and  are 
two  in  number,  right  and  left.  They  are  separated  from  each  other 
by  a  septum,  which  is  usually  slightly  bent  to  the  left  side.  The 
sinuses  are — at  least,  after  adult  life — usuaUy  multilocular,  and 
they  may  extend  backwards  so  as  to  invade  the  basilar  process 
of  the  occipital,  especially  in  old  age.  Each  sinus  may  even 
extend  slightly  into  the  attached  portion  of  the  great  wing.  They 
are  lined  with  mucous  membrane,  which  is  continuous  with  that  of 
the  nasal  fossae,  and  each  opens  anteriorly  by  a  small  circular 
aperture  into  the  spheno-ethmoidal  recess  above  and  behind  the 
corresponding  superior  meatus. 

The  sphenoidal  turbinate  or  spongy  bones  (sphenoidal  turbinals 
or  bones  of  Bertin)  are  situated  on  the  anterior  and  inferior 
surfaces  of  the  body  of  the  sphenoid,  of  which  they  form  a 
large  part.  In  the  adult  they  are  blended  with  the  sphenoid  and 
adjacent  parts  of  the  ethmoid  and  palate  bones,  but  in  early 
life  they  are  quite  distinct.  Each  has  the  form  of  a  three-sided, 
hollow  pyramid,  the  apex  of  which  is  directed  backwards  and  down- 
wards to  the  front  part  of  the  vaginal  process,  whilst  the  base  is  in 
contact  with  the  back  part  of  the  lateral  mass  of  the  ethmoid.  The 
inferior  surface  looks  into  the  posterior  part  of  the  roof  of  the  nasal 
fossa,  and  it  converts  the  spheno-palatine  notch  on  the  upper  border 
of  the  perpendicular  plate  of  the  palate  bone  into  a  foramen.  The 
external  surface  appears  on  the  inner  wall  of  the  spheno-maxillary 
fossa,  and  a  portion  of  it  is  sometimes  seen  on  the  inner  wall  of  the 
orbit,  behind  the  os  planum  of  the  ethmoid.  The  superior  surface 
is  in  contact  with  the  anterior  and  inferior  surfaces  of  the  front  part 
of  the  body  of  the  sphenoid.  It  is  at  the  upper  part  of  this  surface, 
on  either  side  of  the  middle  line,  where  the  openings  of  the  sphenoidal 
air  sinuses  ultimately  appear  as  small  circular  apertures.  When 
the  sphenoidal  spongy  bones  are  broken  away  these  openings  are  of 
large  size  and  irregular  outline. 

The  blood-supply  of  the  bone  is  derived  from  branches  of  the 
deep  temporal  arteries  externally,  the  middle  and  small  meningeal 
internally,  and  the  Vidian,  pterygo-palatine,  and  spheno-palatine 
branches  of  the  internal  maxillary,  as  these  traverse  their  respective 
passages. 

Articulations. — The  sphenoid  articulates  with  fourteen  bones,  as 
follows  :  occipital,  two  temporals,  two  parietals,  frontal,  ethmoid, 
two  sphenoidal  turbinates,  two  malars,  two  palates,  and  vomer.  It 
sometimes  also  articulates  with  the  superior  maxillae. 

Structure.  —  The  body  of  the  bone  is  excavated  into  two  air 
sinuses. 

Varieties. — (i)  Middle  clinoid  process.  (2)  Carotico-clinoid  foramen. 
(3)  Ossification  of  interclinoid  ligament  between  anterior  and  posterior  clinoid 
processes,     (4)  The  lateral  margin  of  the  dorsum  sellae  may  present  a  superior 


THE  BONES  OF  THE  HEAD 


89 


petrosal  process  for  the  attachment  of  the  petro-sphenoidal  liganient,  which 
connects  it  vdih  a  projection  sometimes  present  on  the  inner  part  of  the  superior 
border  of  the  petrous  portion  of  the  temporal.  This  ligament,  which  is  some- 
times ossilied,  bridges  over  a  foranren  through  which  the  inferior  petrosal 
venous   sinus   and   sixth   cranial   nerve   pass.      (5)   Pterygo-spinous   foramen. 

(6)  Foramen    ovale    and    foramen    spinosum    are    sometimes    incomplete. 

(7)  Foramen  Vesalii.  (8)  Canaliculus  innominatus.  (9)  The  cranio-pharyn- 
geal  canal  may  remain  persistent,  opening  into  the  pituitary  fossa. 

Ossification. — The  sphenoid  is  developed  in  cartilage,  with  the  exception 
of  the  internal  pterygoid  plates,  which  are  developed  in  hbrous  tissue.*  The 
bone  is  originally  divided  into  two  parts — presphenoid,  representing  the  part 
of  the  body  in  front  of  the  olivary  eminence,  and  the  small  wings  ;  and  post- 
sphenoid,  including  the  part  of  the  body  behind  the  olivary  eminence,  the 
great  wings,  and  the  pterygoid  processes.  The  postsphenoid  division  is 
developed  from  four  pairs  of  centres.  One  pair  appear  in  the  eighth  week 
of  intra-uterine  life,  one  at  either  side  in  the  great  wing  between  the  foramen 


-Small  Wino 


Presphenoid  Portion  of  Body 


Great  Wing 


Dorsum  Sells 
JZ      Internal  Pterygoid  Plate 


Fig.    56. — The  Sphenoid  Bone  in  Early  Life. 

I,    Presphenoid    Division ;     II,    Postsphenoid    Portion   of   Body ;    III,    Great 
Wing  and  Pterygoid  Process;     IV,  Elements  of  Pterygoid  Process. 

rotundum  and  foramen  ovale,  and  from  this  ossification  extends  outwards 
into  the  great  wing  and  downwards  into  the  external  pterygoid  plate.  Another 
pair  appear  about  the  same  time  in  the  sella  turcica  on  either  side  of  the 
cranio-pharyngeal  canal,  from  which  ossification  extends  around  the  canal, 
gradually  constricting  it,  and  finally  leading  to  its  closure.  At  this  time  another 
pair  (sphenotics  of  Bland-Sutton)  appear,  one  at  either  side,  for  the  lingula. 
In  the  fourth  month  (ninth  or  tenth  week,  Fawcett)  another  pair  of  centres 
appear  in  fibrous  tissue,  one  at  either  side,  for  the  internal  pterygoid  plate, 
which  unites  with  the  external  pterygoid  plate  before  the  sixth  month. 
The  presphenoid  division  is  developed  from  two  pairs  of  centres.  Two 
appear  in  the  ninth  week,  one  at  either  side,  external  to  the  optic 
foramen,  for  the  small  wing.  Another  pair  apj)ear  in  the  eleventh  week 
internal  to  the  optic  foramina  for  the  presphenoid  portion  of  the  body. 
The  latter  pair  soon  unite  with  each  other,  and  also  with  those  for  the  small 
wings.  The  presphenoid  division,  bearing  the  small  wings,  joins  the  post- 
sphenoid division  shortly  before  birth  in  the  region  of  the  olivary  eminence. 
At  birth  the  place  of  junction  is  indicated  by  a  wide  depression  on  the  under 

*  According  to  recent  observations  made  by  I-'awcett  the  external  pterygoid 
plates  are  also  develojjed  in  fibrous  tissue. 


go  A  MANUAL  OF  ANATOMY 

aspect  of  that  eminence,  which  may  even  extend  through  it  and  give  rise 
to  a  small  foramen  on  its  upper  surface. 

At  birth  the  bone  is  composed  of  three  parts — a  central,  representing  the 
presphenoid  and  postsphenoid  portions  of  the  body,  the  former  bearing 
the  small  wings  ;  and  two  lateral,  each  of  which  represents  a  great  wing  bearing 
a  pterygoid  process.  In  the  first  year  the  hngula  joins  the  great  wing,  and 
the  wing  and  body  unite.  About  the  same  time  the  small  wings  come  together 
and  blend  over  the  anterior  part  of  the  upper  surface  of  the  presphenoid 
portion  of  the  body,  where  they  give  rise  to  a  smooth,  elevated,  flat  platform, 
called  the  jugum  sphenoidale. 

In  foetal  life  a  canal,  called  the  cranio-pharyngeal  canal,  leads  downwards 
from  the  sella  turcica  into  the  body,  and  contains  a  process  of  the  dura 
mater.  This  canal  is  the  remains  of  a  cleft  originally  present  in  the  base  of 
the  skull,  through  which  a  diverticulum  of  the  buccal  epiblast,  known  as  the 
pouch  of  Rathke,  originally  passed  upwards  to  form  the  anterior  lobe  of  the 
pituitary  body. 

The  sphenoidal  air  sinuses  do  not  appear  until  after  the  seventh  year. 

In  some  animals  the  presphenoid  and  postsphenoid  portions  remain 
permanently  separate,  and  the  internal  pterygoid  plates  form  the  pterygoid 
bones. 

The  sphenoidal  turbinate  bones  commence  to  ossify  in  the  fifth  month  of 
intra-uterine  life.  At  birth  each  partially  envelops  a  small  extension  of  the 
nasal  mucous  membrane,  and  by  the  third  year  it  has  surrounded  it  in  the 
form  of  a  bony  capsule,  except  anteriorly,  where  an  opening,  called  the  sphe- 
noidal foramen,  is  left.  Subsequently  a  portion  of  this  capsule  becomes 
absorbed,  and  its  place  is  taken  by  the  presphenoid,  which  latter,  after  the 
seventh  year,  is  gradually  invaded  by  the  original  extension  of  the  nasal 
mucous  membrane.  The  sphenoidal  spongy  bones  become  ankylosed  to  the 
ethmoid  about  the  fourth  year,  and  are  sometimes  regarded  as  belonging 
to  that  bone.  By  the  twelfth  year  they  have  become  united  to  the  sphenoid, 
and  also  to  the  palate  bones. 

The  Ethmoid  Bone. 

The  ethmoid  bone  is  situated  at  the  anterior  part  of  the 
base  of  the  skull,  where  it  lies  in  the  middle  line  in  front  of  the 
sphenoid.  A  portion  of  it  occupies  the  ethmoidal  notch  between 
the  orbital  plates  of  the  frontal,  whence  the  greater  part  of  the 
bone  projects  downwards  to  take  part  in  the  formation  of  the 
orbits  and  nasal  fossae.  The  only  portions  of  the  bone  visible  in 
the  interior  of  the  base  are  the  cribriform  plate  and  crista  galli. 
It  is  irregularly  cubical,  its  long  axis  being  directed  from  before 
backwards,  and  it  is  remarkable  for  its  lightness,  which  is  due  to 
the  great  number  of  enclosed  air  cells,  these  being  surrounded  by 
very  thin  plates  of  bone.  It  is  composed  of  four  parts,  namely, 
a  cribri'orm  plate,  a  perpendicular  plate,  and  two  lateral  masses. 

The  cribriform  plate  connects  the  upper  borders  of  the  lateral 
masses,  and  enters  into  the  formation  of  the  middle  division  of  the 
anterior  cranial  fossa,  where  it  occupies  the  ethmoidal  notch  of  the 
frontal  bone.  In  the  middle  line  anteriorly  it  presents  an  upward 
extension  of  the  perpendicular  plate,  called  the  crista  galli.  This 
is  a  stout,  triangular,  laterally-compressed  process,  which  presents 
a  smooth,  sloping  posterior  border,  for  the  falx  cerebri.  The 
anterior  border,  short  and  vertical,  is  somewhat  narrow  above, 
but  soon  expands  into  two  alar  processes,  for  the  frontal  bone, 


THE  BONES  OF  THE  HEAD 


91 


and  it  here  sometimes  completes  the  foramen  csecum.  The 
posterior  border  is  prolonged  backwards  as  a  median  ridge,  and 
on  either  side  of  this  ridge  and  the  crista  galli  is  the  olJEactory 
groove,  which  lodges  the  olfactory  tract  and  bulb.  Each  half  of 
the  cribriform  plate,  which  lies  in  the  roof  of  the  corresponding 
nasal  fossa,  is  pierced  by  foramina  for  the  filaments  of  the  olfactory 
bulb.  The  foramina  in  each  half  are  arranged  in  three  sets,  as 
follows — a  middle  set,  which  are  simple  perforations,  and  an  internal 
and  external  set,  which  lead  into  small  canals.  These  canals 
descend  on  the  perpendicular  plate  and  inner  surface  of  the  lateral 
mass  respectively,  branching  and  opening  out  as  they  descend. 
All  the  foramina  lead  to  the  upper  part  of  the  corresponding  nasal 
fossa.  At  the  anterior  and  inner  part  of  each  half  of  the  cribriform 
plate,  close  to  the  side  of  the  crista  galli,  near  its  anterior  border, 


Crista  Gall 
Nasal  Groove. 


Groove  for  Anrerior 
Ethmoidal  Canal 


^Vertical  Plate 
-Right  Alar  Process 

— ^Ant.  Ethmoidal  Cells 

._  InfiuKlibulum 


Orbital  Plate  1  Olfactory  Groove  on  Cribriform  Plate 

Groove  for  Post.  Ethmoidal  Canal 

Fig.   57. — The  Ethmoid  Bone  (Superior  View). 

there  is  an  antero-posterior  fissure,  called  the  nasal  slit,  which 
transmits  the  nasal  branch  of  the  ophthalmic  nerve  and  nasal  branch 
of  the  anterior  ethmoidal  artery  to  the  nasal  fossa.  Leading 
backwards  and  outwards  from  this  slit  to  the  anterior  ethmoidal 
groove  on  the  upper  border  of  the  lateral  mass  is  the  nasal  groove, 
also  for  the  nasal  nerve.  The  posterior  border  of  the  cribriform 
j)late  articulates  with  the  ethmoidal  spine  of  the  sphenoid. 

The  perpendicular  plate  (mesethmoid)  extends  downwards  from 
the  cribriform  plate  in  the  middle  line.  It  lies  between  the  lateral 
masses,  where  it  forms  about  the  upper  third  of  the  nasal  septum, 
and  it  is  usually  inclined  more  to  one  side  than  the  other.  It  is 
very  thin  and  irregularly  quadrilateral.  The  superior  border  projects 
above  the  cribriform  plate  and  forms  the  crista  galli.  The  inferior 
border  articulates,  in  front,  with  the  septal  cartilage  of  the  nose, 
and  behind,  with  the  ala;  of  Ihe  vomer  in  the  intervening  cleft, 


92 


A  MANUAL  OF  ANATOMY 


with  which  alae  it  is  usually  ankylosed  in  adult  life.  The  anterior 
border  articulates  with  the  nasal  spine  of  the  frontal  and  the 
nasal  crest  of  the  nasal  bones.  The  posterior  border  articulates 
with  the  crest  of  the  sphenoid.  Each  lateral  surface  looks  into  the 
corresponding  nasal  fossa,  and  presents  superiorly  several  small 
canals  and  grooves,  which  lead  downwards  from  the  internal  set 
of  foramina  in  each  half  of  the  cribriform  plate,  and  transmit 
olfactory  filaments. 

The  lateral  masses  or  lateral  ethmoids  (ethmo-turbinals)  form  the 
principal  part  of  the  bone,  and  contain  a  number  of  air  cells  enclosed 
within  very  thin  osseous  plates.  Each  lateral  mass  or  labyrinth 
is  elongated  from  before  backwards,  and  presents  two  surfaces  and 
four  borders. 

The  external  surface,  smooth  and  quadrilateral,  with  the  long  axis 
directed  from  before  backwards,  is  called  the  OS  planum  or  orbital 


Alar  Process 


Infundibulum.,__ 


Ant.  Ethm.  Cells-— -"I./ 


Vertical  Plate 


Crista  Galli 

Groove  for  Ant.  Ethm.  Canal 

Groove  for  Post.  Ethm.  Canal 

Orbital  Plate 


I  Middle  Meatus 

Uncinate  Process  Inf.  Turbinate  Process 

Fig.   58. — The  Ethmoid  Bone  (Lateral  View). 


plate,  and  forms  the  principal  part  of  the  inner  wall  of  the  orbit. 
It  articulates  superiorly  with  the  inner  border  of  the  orbital  plate 
of  the  frontal,  anteriorly  with  the  lachrymal,  inferiorly  with  the 
inner  margin  of  the  orbital  plate  of  the  superior  maxilla,  and 
behind  this  with  the  orbital  process  of  the  palate  bone,  close  to 
the  postero-inferior  angle,  and  posteriorly  with  the  sphenoid,  or, 
it  may  be,  with  a  portion  of  the  sphenoidal  spongy  bone.  At  the 
lower  part  of  the  external  surface,  below  the  os  planum,  there  is  a 
deep  channel,  elongated  from  before  backwards,  which  forms  the 
middle  meatus  of  the  nose,  and  is  limited  below  by  the  inferior 
rolled  border  of  the  inferior  turbinate  process.  This  groove  turns 
upwards  in  front,  under  cover  of  the  anterior  part  of  the  inferior 
turbinate  process,  and  is  continued  into  the  infundibulum  which 
communicates  with  the  frontal  sinus  of  the  same  side.  The  anterior 
ethmoidal  cells  open  into  the  ascending  part  of  the  middle  meatus, 
whilst  the  middle  ethmoidal  cells  and  the  antrum  of  Highmore 


THE  BONES  OF  THE  HEAD  93 

open  into  its  horizontal  part.     Lying  in  the  anterior  part  of  this 
meatus  is  the  uncinate  process. 

The  internal  surface  of  the  lateral  mass  forms  a  part  of  the 
outer  wall  of  the  nasal  fossa.  Superiorly  it  presents  several  small 
canals  and  grooves,  which  lead  downwards  from  the  external  set 
of  foramina  in  the  cribriform  plate  and  transmit  olfactory  filaments. 
This  surface  is  doubly  convoluted,  and  presents  the  superior  and 
inferior  turbinate  processes,  which  are  sometimes  spoken  of  as  the 
superior  and  middle  spongy  bones,  or  conchce.  These  are  continuous 
with  each  other  in  front,  but  posteriorly  they  are  separated  by  the 
superior  meatus,  which  is  directed  obliquely  forwards  and  upwards, 
and  communicates  with  the  pcsterior  ethmoidal  cells.  The 
superior  turbinate  process  is  short,  and  overhangs  the  superior 
meatus.  The  inferior  turbinate  process  is  longer  and  more  con- 
voluted than  the  superior.     Its  lower  border,  which  is  thick,  is 

Cribriform  Plate         Groove  for  Ant.  Ethiu.  Canal 
Groove  for  Post.  Ethmoidal  Canal         ]        1        Nasal  Groove 


Post.  Ethmoidal  Cells 


Sup.  Turbinate  Process 

Inf.  Turbinate  Process' g^p^^;^^'  ^j^^^^,^^  Uncinate  Process 

Fig.  59. — The  Left  L.^teral  Mass  of  the  Ethmoid  Bone 
(Internal  View). 

rolled  outwards,  and  has  been  referred  to  in  connection  with  the 
outer  surface.  It  is  free,  as  are  also  its  thick  anterior  and  pointed 
posterior  extremities.  This  process  overhangs  the  middle  meatus. 
Both  turbinate  processes  are  pierced  by  nutrient  foramina,  and 
present  grooves  for  olfactory  filaments. 

The  superior  border  is  covered  by  the  bevelled  inner  margin  of 
the  orbital  plate  of  the  frontal,  which  closes  in  the  depressions 
upon  it,  and.  converts  them  into  air  cells.  Besides  these  depres- 
sions this  border  presents  two  transverse  grooves  about  half  an 
inch  apart,  which,  with  corresponding  grooves  on  the  orbital 
l>]Hte  of  the  frontal,  form  the  anterior  and  posterior  ethmoidal  or 
internal  orbital  canals.  These  open  upon  the  inner  wall  of  the 
orbit,  and  the  anterior  transmits  the  anterior  ethmoidal  vessels 
and  the  nasal  nerve,  whilst  the  posterior  gives  ])assage  to  the 
posterior  ethmoidal  vessels  and  the  spheno-ethmoidal  neive.  The 
infaior    border,    which    is    free    on    the    outer    wall   of    the    nasal 


94  A  MANUAL  OF  ANATOMY 

fossa,  is  formed  by  the  lower  border  of  the  inferior  turbinate 
process.  Anteriorly  it  articulates  with  the  superior  turbinate 
crest  of  the  superior  maxilla,  and  posteriorly  with  the  ethmoidal 
or  superior  turbinate  crest  of  the  palate  bone.  The  anterior  border, 
like  the  superior,  presents  depressions,  which  form  air  cells  when 
the  lachrymal  and  nasal  process  of  the  superior  maxilla  are  in 
position.  This  border  projects  slightly  in  advance  of  the  front 
of  the  OS  planum,  and  from  the  lower  part  of  this  projecting 
portion  there  springs  the  uncinate  process.  This  is  a  long,  thin, 
curved  plate  which  extends  downwards,  backwards,  and  slightly 
outwards  into  the  anterior  part  of  the  middle  meatus.  In  its 
course  it  crosses  the  opening  of  the  antrum  of  Highmore  in  the 
superior  maxilla,  and  thus  forms  part  of  the  inner  wall  of  that 
air  sinus.  The  lower  border  of  the  process  presents  two  spur-like 
projections,  between  which  the  border  is  markedly  concave.  The 
posterior  terminal  spur  articulates  with  the  ethmoidal  process  of 
the  inferior  turbinate  bone.  The  posterior  border  of  the  lateral 
mass  presents  a  few  depressions,  closed  by  the  sphenoidal  spongy 
bone  and  orbital  process  of  the  palate  bone,  which  latter  process 
becomes  ankylosed  with  it  about  the  fourth  year. 

The  ethmoidal  cells  are  contained  within  each  lateral  mass,  and 
are  lined  with  mucous  membrane,  which  is  continuous  with  that  of 
the  nose.  They  are  arranged  in  three  sets — anterior,  middle,  and 
posterior.  The  anterior  ethmoidal  cells,  along  with  the  frontal  sinus 
of  the  same  side,  open  by  a  common  passage,  already  described 
as  the  infundibulum,  into  the  ascending  front  part  of  the  middle 
meatus  ;  the  middle  ethmoidal  cells  open  into  the  horizontal  part 
of  the  middle  meatus ;  and  the  posterior  ethmoidal  cells  open  into 
the  superior  meatus. 

The  bone  receives  its  blood  -  supply  from  the  anterior  and 
posterior  ethmoidal  branches  of  the  ophthalmic,  and  the  spheno- 
palatine branch  of  the  internal  maxillary. 

Articulations. — The  ethmoid  articulates  with  fifteen  bones,  as 
follows  :  (i)  frontal  (nasal  spine  and  orbital  plates)  ;  (2)  sphenoid 
(ethmoidal  spine  and  sphenoidal  crest)  ;  (3)  two  sphenoidal  spongy 
bones  ;  (4)  two  nasal  bones  (nasal  crest)  ;  (5)  vomer  (cleft  between 
alse)  ;  (6)  two.  palate  bones  (ethmoidal  or  superior  turbinate  crests 
and  orbital  processes)  ;  (7)  two  lachrymals  (upper  part  of  internal 
surface)  ;  (8)  two  superior  maxillse  (nasal  processes,  orbital  plates, 
and  opening  of  each  antrum)  ;  and  (9)  two  inferior  turbinates 
(ethmoidal  processes). 

Structure. — The  lateral  masses  are  excavated  into  many  thin- 
walled  air  cells,  and  the  crista  galli  contains  a  small  amount  of 
cancellated  tissue. 

Ossification. — The  ethmoid  is  developed  in  cartilage  from  tliree  centres. 
Two  of  these  appear  in  the  fifth  month  of  intra- uterine  life,  one  in  each  os 
planum,  from  which  ossification  extends  into  the  superior  and  inferior  turbinate 
processes.  At  birth  the  lateral  masses  are  ossified,  but  the  perpendicular 
plate  and  crista  galli  are  cartilaginous.  In  the  first  year  a  centre  appears 
at  the  base  of  the  crista  galli,  and  from  this  ossification  extends  upwards  into 


THE  BONES  OF  THE  HEAD  95 

that  process,  downwards  into  the  perpendicular  plate,  and  outwards  into 
the  cribriform  plate,  into  which  latter  osseous  matter  also  extends  inwards 
from  each  lateral  mass.  The  three  original  parts  unite  about  the  fifth  year. 
The  osseous  ethmoidal  cells  usually  make  their  appearance  about  the  third  year. 

The  Superior  Maxillary  Bones. 

The  superior  maxillary  bone  forms,  with  its  fellow,  a  large  part 
of  the  face,  and,  besides  supporting  the  upper  teeth  of  its  own 
side,  it  enters  into  the  formation  of  the  orlDit,  nasal  fossa,  and 
hard  palate.  It  is  composed  of  a  central  portion  or  body,  and 
four  processes — nasal,  malar,  alveolar,  and  palatal. 

The  body  is  excavated  into  a  large  cavity,  called  the  antrum  of 
Highmore  or  maxillary  air  sinus,  and  it  presents  four  surfaces — 
antero-external,  postero-external,  superior,  and  internal. 

The  antero-external  or  facial  surface  is  limited  above  by  the 
infra-orbital  border,  below  by  the  alveolar  border,  internally  by  the 
mesial  border,  presenting  the  nasal  notch,  and  externally  by  the 
malar  process  and  a  ridge  of  bone  extending  downwards  from  it 
to  the  first  molar  alveolus.  It  presents  interiorly  five  ridges, 
coinciding  with  the  roots  of  the  incisor,  canine,  and  bicuspid 
teeth,  of  which  that  of  the  canine  is  conspicuous,  and  is  called  the 
canine  ridge.  Internal  to  this  ridge  is  the  incisor  or  myrtiforra 
fossa  (like  a  m^-rtle-berry),  which  gives  origin  internally  to  the 
depressor  alse  nasi,  and  externally  to  a  deep  slip  of  the  orbicularis 
oris,  whilst  above,  and  external  to,  the  latter  the  compressor  naris 
arises.  External  to  the  canine  ridge  is  the  canine  fossa,  which, 
at  its  upper  part,  gives  origin  to  the  levator  anguli  oris,  the  bone 
being  here  thin  and  translucent  in  front  of  the  antrum.  Above 
the  canine  fossa,  near  the  infra-orbital  border,  is  the  infra-orbital 
foramen,  which  is  the  outlet  of  the  infra-orbital  canal,  and  trans- 
mits the  infra-orbital  nerve  and  vessels.  Immediately  above  this 
foramen  the  levator  labii  superioris  arises.  The  mesial  border 
of  the  facial  surface  presents  the  deep  nasal  notch,  at  the  lower 
and  inner  part  of  which  is  a  sharp  projection,  forming,  with  its 
fellow,  the  anterior  nasal  spine,  below  which  the  border  is  vertical. 

The  postero-external  or  zygomatic  surface  is  situated  behind  the 
malar  process  and  the  ridge  connecting  that  process  with  the  first 
molar  alveolus.  Superiorly  it  is  limited  by  the  posterior  border 
of  the  orbital  surface,  inferiorly  by  the  molar  portion  of  the  alveolar 
border,  and  posteriorly  by  the  posterior  border  of  the  bone.  It 
looks  into  the  zygomatic  and  spheno-maxillary  fossae,  and  its 
outline  is  convex.  Towards  the  centre  it  presents  the  openings 
of  two  or  three  posterior  dental  canals,  which  lead  to  the  molar 
alveoli,  and  transmit  branches  of  the  posterior  superior  dental 
nerve  and  artery.  At  the  lower  and  back  part  this  surface  gives 
rise  to  the  tuberosity,  which  lies  above  and  behind  the  last  molar 
tooth.  This  tuberosity  articulates  with  the  pyramidal  process  of 
the  palate  bone,  and  gives  origin  to  some  fibres  of  the  internal 
pterygoid  muscle. 


96 


A  MANUAL  OF  ANATOMY 


The  superior  or  orbital  surface  is  triangular,  smooth,  and  slightly 
concave,  and  it  forms  the  greater  part  of  the  floor  of  the  orbit. 
This  portion  of  the  bone  is  known  as  the  orbital  plate.  It  presents 
the  infra-orbital  groove,  which,  commencing  at  the  posterior  border 
in  a  notch,  ultimately  becomes  converted  into  the  infra-orbital 
canal.  This  canal  transmits  the  infra-orbital  nerve  and  vessels. 
From  its  posterior  part  the  middle  dental  canal,  for  the  middle 
superior  dental  nerve  and  artery,  passes  downwards  and  forwards 


Nasal  Process 


For  Lachrymal  Bone 
Lachrymal  Tubercle      \ 


For  Nasal  Bone 


Lachi-ymal  Notch 
Orbital  Surface 
Infra-orbital  Groove     I 


Openings  of 
Post.  Dental  Canals 


Nasal  Notch 


_. .interior  Nasal 
Spine 


Tuberosity    ' 
Zygomatic  Surface 


Malar  Process 


Palatal  Process 
Incisor  Fossa 
Canine  Fossa 


Fig.  6o. 


Infra-orbital  Foramen 

-The  Right  Superior  Maxillary  Bone  (External  View). 


to  the  bicuspid  alveoli,  lying  at  first  in  the  postero-external  wall 
of  the  antrum,  and  subsequently  in  the  antero-external  wall.  This 
canal  is  often  for  the  most  part  a  groove.  The  anterior  dental 
canal,  for  the  anterior  superior  dental  nerve  and  artery,  descends 
in  a  branching  manner  from  the  anterior  part  of  the  infra-orbital 
canal  to  the  incisor  and  canine  alveoli,  lying  in  the  antero-external 
wall  of  the  antrum.  At  the  anterior  and  inner  part  of  the  orbital 
plate,  external  to  the  lachrymal  groove,  there  is  a  slight  depression 
which  gives  origin  to  the  inferior  oblique  muscle  of  the  eyeball. 


THE  BONES  OF  THE  HEAD  97 

The  borders  of  the  orbital  surface  are  anterior,  posterior,  and 
internal.  The  anterior  border  coincides  with  the  infra-orbital 
border.  The  posterior  border,  which  has  an  inclination  outwards, 
forms  the  anterior  boundary  of  the  spheno-maxillary  fissure,  and 
presents  a  notch  representing  the  commencement  of  the  infra- 
orbital groove.  The  internal  border,  antero-posterior  in  direction, 
presents,  behind  the  nasal  process,  the  lachrymal  notch  for  the 
lachrymal  bone,  and  behind  this  it  articulates,  from  before  back- 
wards, with  the  lower  border  of  the  os  planum  of  the  ethmoid  and 
the  orbital  process  of  the  palate  bone.  This  border  presents  a 
few  depressions  which  close  in  ethmoidal  cells. 

The  internal  or  nasal  surface  forms  part  of  the  outer  wall  of  the 
nasal  fossa.  It  is  limited  in  front  by  the  mesial  border  of  the 
bone,  behind  by  the  posterior  border,  above  by  the  internal 
border  of  the  orbital  surface,  and  below  for  the  most  part  by  the 
palatal  process.  It  presents  the  opening  of  the  antrum  of 
Highmore,  in  front  of  which  is  the  deep  lachrymal  groove,  directed 
downwards,  outwards,  and  backwards,  and,  after  a  course  of 
about  h  inch,  opening  into  the  front  part  of  the  inferior  meatus 
of  the  ""nose.  This  groove  is  converted  posteriorly  and  internally 
into  the  lachrymal  canal  by  the  lachrymal  and  inferior  turbinate 
bones,  and  it  transmits  the  nasal  duct.  In  front  of  the 
lachrymal  groove  is  a  slightly  oblique  ridge,  called  the  inferior 
turbinate  crest,  for  articulation  with  the  inferior  turbinate  bone, 
and  below  this  is  a  smooth  concave  surface  which  forms  the  anterior 
part  of  the  inferior  meatus.  Above  the  crest  is  the  commencement 
of  another  smooth  surface,  which  extends  upwards  on  to  the  inner 
aspect  of  the  nasal  process,  and  forms  the  outer  wall  of  the  atrium 
of  the  middle  meatus.  Behind  the  opening  of  the  antrum  the 
internal  surface  articulates  with  the  perpendicular  plate  of  the 
palate  bone,  and  it  presents,  from  the  centre  downwards,  a  groove, 
directed  downwards  and  forwards,  which,  with  the  palate  bone, 
forms  the  posterior  palatine  canal  for  the  great  or  anterior  palatine 
nerve,  and  the  superior  or  descending  palatine  artery.  Above  the 
opening  of  the  antrum  are  a  few  depressions  on  the  internal  border 
01  the  orbital  surface,  forming  ethmoidal  cells. 

The  nasal  or  frontal  process  ascends  vertically  from  the  mesial 
part  of  the  facial  surface  above  the  nasal  notch.  It  is  somewhat 
triangular,  and  presents  two  surfaces  and  three  borders.  The 
external  surface  is  continuous  with  the  facial  surface  of  the  body, 
and  gives  attachment  to  the  orbicularis  palpebrarum,  tendo  oculi, 
and  levator  labii  superioris  ala;que  nasi.  The  intrnal  surface 
forms  part  of  the  outer  wall  of  the  nasal  fossa,  and,  at  its  back  part 
superiorly,  it  presents  one  or  two  depressions,  com])leting  cells 
on  the  anterior  border  of  the  lateral  mass  of  the  ethmoid.  The 
surface  is  crossed  ol)liquely  backwards  and  ujnvards  by  a  ridge, 
called  the  agger  nasi  (mound)  or  superior  turbinate  crest,  which 
represents  the  naso-turbinal  of  most  mammals  (Schwalbc)-  This 
cre?t   bounds  superiorly   the   atrium   of   the  middle   meatus,   and 

7 


A  MANUAL  OF  ANATOMY 


articulates  posteriorly  with  the  anterior  extremity  of  the  inferior 
turbinate  process  of  the  ethmoid.  Above  the  agger  nasi  there  is 
a  groove,  called  the  sulcus  olfadorius.  The  superior  border  is  short, 
thick,  and  serrated  for  the  frontal.  The  anterior  border  is  sharp 
and  articulates  with  the  nasal.  The  posterior  border  is  thick, 
and  in  its  lower  part  presents  a  continuation  of  the  lachrymal 
groove,  which  here  lodges  the  lachrymal  sac.  The  lips  of  this 
part  of  the  groove  are  sharp,  the  inner  articulating  with  the 
lachrymal,  and  the  outer,  which  is  crescentic,  being  continuous 

Sulcus  Olfactorius 

,Sup.  Turbinate  Crest  (Agger  Nasi) 
Atrium  of  Middle  Meatus 
Inf.  Turbinate  Crest 

Int.  Bord.  of  Orbital  Surface 
Antrum 


Anterior  Nasal  Spine      | 
Incisor  Crest 
Incisor  or  Naso-Palatine  Groove 


Post.  Palatine  Groove 


Palatal  Process 


Inferior  Meatus 


Nasal  Crest 
Lachrymal  Groove 

Fig.  6i.— The  Right  Superior  Maxillary  Bone  (Internal  View). 

with  the  infra-orbital  margin,  at  which  point  there  is  a  projection, 
called  the  lachrymal  tubercle. 

The  malar  process  is  stout  and  triangular.  Its  anterior  surface 
is  continuous  with  the  facial  surface  of  the  body,  and  its  posterior 
with  the  zygomatic  surface,  whilst  the  superior  surface  is  rough 
and  slightly  serrated  for  the  malar. 

The  alveolar  process  forms  the  dependent  part  of  the  bone, 
and  is  thick  and  curved,  being  convex  externally  and  concave 
internally.  The  outer  plate  is  known  as  the  labial  plate,  and  the 
inner  as  the  lingual.     The  two  plates  are  widely  separated,  and 


THE  BONES  OF  THE  HEAD  99 

the  intervening  space  is  partitioned  off  into  alveoli  or  sockets  by 
septa  which  pass  between  the  two  plates.  The  number  of  alveoli 
in  the  adult  bone  is  as  a  rule  eight,  and  they  gradually  narrow 
towards  their  upper  or  deep  ends,  where  they  are  perforated  by 
foramina  for  the  nerves  and  arteries  of  the  teeth.  They  lodge  the 
roots  of  the  teeth,  which,  in  order  from  the  middle  line  outwards 
and  backwards,  are  as  follows  :  central  incisor,  lateral  incisor, 
canine,  first  bicuspid,  second  bicuspid,  and  first,  second,  and  third 
molars.  The  alveoli  correspond  in  shape  with  the  roots  of  the 
teeth,  the  canine  being  the  deepest.  The  outer  surface  of  the 
alveolar  border,  over  the  extent  of  the  three  molar  sockets,  gives 
origin  to  fibres  of  the  buccinator. 

The  palatal  process  is  situated  on  the  internal  surface  of  the 
body,  from  which  it  projects  horizontally  inwards,  and,  with  its 
fellow,  it  forms  three-fourths  of  the  hard  palate.  It  is  quadrilateral, 
and  presents  two  surfaces  and  four  borders.  The  superior  surface 
forms  three-fourths  of  the  floor  of  the  nasal  fossa,  and  is  smooth, 
concave,  and  covered  in  the  recent  state  by  the  nasal  mucous 
membrane.  The  inferior  surface  forms  a  part  of  the  hard  palate, 
and  is  rough,  arched,  and  covered  in  the  recent  state  by  the  buccal 
mucous  membrane.  It  presents  several  depressions  for  the  palatal 
mucous  glands,  and  is  perforated  by  several  nutrient  foramina. 
Laterally  it  is  marked  by  a  groove,  directed  from  behind  forwards, 
for  the  nerve  and  artery  which  reach  the  hard  palate  through  the 
posterior  palatine  canal.  The  posterior  border  stops  short  of  the 
back  part  of  the  alveolar  border,  and  is  short  and  serrated  for 
the  horizontal  plate  of  the  palate  bone.  The  anterior  border, 
superiorly,  forms  the  lower  part  of  the  nasal  notch.  The  external 
border  is  attached  to  the  body.  The  internal  or  mesial  border 
is  faintly  serrated,  and  articulates  with  its  fellow.  At  the 
place  of  meeting  it  is  elevated  into  a  ridge,  forming,  with  that 
of  its  fellow,  the  nasal  crest,  which  is  grooved  to  receive  the  lower 
border  of  the  vomer.  This  mesial  ridge  becomes  prominent  in 
front,  where  it  forms  the  incisor  crest,  which  is  projected  to 
constitute,  with  its  fellow,  the  anterior  nasal  spine.  It  supports 
the  septal  nasal  cartilage,  and  the  anterior  extremity  of  the  vomer 
lies  behind  it. 

Close  to  the  outer  side  of  the  incisor  crest  the  palatal 
process  is  pierced  by  an  opening  leading  into  a  canal,  which  is 
bounded  internally  by  a  thin  plate  of  bone,  and  descends  to  the 
front  part  of  the  hard  palate,  being  ultimately  converted  into  a 
groove,  due  to  its  inner  thin  wall  becoming  deficient.  This  passage 
is  variously  known  as  the  incisor  or  naso-j)alatine  canal,  or  canal 
of  Stensen  (Steno),  and  the  two  canals,  right  and  left,  in  the 
articulated  condition  form  interiorly  a  large  orifice,  called  the 
anterior  palatine  fossa.  This  fossa,  which  is  somewhat  diamond- 
shaped,  is  situated  in  the  middle  line  of  the  hard  palate,  behind 
the  central  incisor  teeth.  On  looking  into  it  from  below  four 
foramina  are  seen,   two  of  which  are  placed  in  the  middle  line, 

7—2 


loo  A  MANUAL  OF  ANATOMY 

where  they  he  in  the  intermaxillary  suture.  These  are  known 
as  the  foramina  of  Scarpa,  and  they  transmit  the  naso-palatine 
nerves,  the  lefi  nerve  passing  through  the  anterior,  which  usually 
communicates  with  the  left  nasal  fossa,  and  the  right  through 
the  posterior,  which  usually  communicates  with  the  right  nasal 
fossa.-  The  other  two  foramina  are  situated  one  at  either  side, 
and  are  known  as  the  foramina  of  Stensen,  and  the  canal  into  which 
each  leads  opens  superiorly  on  the  floor  of  the  corresponding  nasal 
fossa,  close  to  the  outer  side  of  the  incisor  crest.  Each  of  Stensen' s 
canals  transmits  a  branch  of  the  superior  or  descending  palatine 
artery  from  the  anterior  palatine  fossa  to  the  nasal  fossa.  The 
inner  wall  of  Stensen's  canal,  on  each  side,  represents  the  mesial 
palatal  process  of  the  premaxilla  or  intermaxillary  bone,  and  also 
a  portion  developed  from  the  prepalatine  centre.  The  canals  of 
Stensen  correspond  to  the  incisor  foramina  of  many  animals — 
e.g.,  the  ruminantia,  in  which  they  are  of  large  size,  and  each  opens 
independently  on  the  front  part  of  the  hard  palate  as  a  large  aper- 
ture, there  being  no  anterior  palatine  fossa.  In  such  animals  each 
incisor  foramen  leads  up  to  the  orifice  of  Jacobson's  organ,  which 
is  a  supplementary  organ  of  smell.  In  man  the  canals  of  Stensen 
are  the  remains  of  a  communication  which  existed  in  early  foetal 
life  between  the  nasal  and  buccal  cavities. 

Passing  transversely  outwards  from  the  anterior  palatine  fossa 
at  its  back  part  to  the  interval  between  the  lateral  incisor  and 
canine  teeth  a  suture  is  always  present  in  early  life,  and  may 
persist  in  the  adult,  which  indicates  the  line  of  junction  of  the 
maxillary  portion  proper  and  the  premaxilla  or  intermaxillary  bone, 
the  latter  representing  the  part  which  bears  the  central  and  lateral 
incisor  teeth.  This  intermaxillary  portion  forms  an  independent 
bone  in  many  animals. 

The  antrum  of  Highmore  or  maxillary  air  sinus  is  situated 
within  the  body  of  the  bone,  and  is  of  large  size,  its  capacity  in 
health  being  equal  to  about  2  drachms.  It  has  the  shape  of  a 
four-sided  pyramid,  and  is  lined  with  mucous  membrane  continuous 
with  that  of  the  nasal  fossa.  The  apex  corresponds  to  the  malar 
process,  and  the  base  represents  the  internal  or  nasal  aspect.  The 
superior  wall  or  roof  is  formed  by  the  orbital  plate.  The  inferior 
wall  or  floor  is  formed  by  that  portion  of  the  alveolar  border  which 
contains  the  molar  and  second  bicuspid  alveoli,  and,  in  some  cases, 
the  first  bicuspid  alveolus  also.  It  is  often  very  irregular,  due  to 
projections  of  the  upper  ends  of  the  alveoli,  and  in  some  cases  the 
root  of  the  first  molar,  and,  it  may  be,  that  of  the  second,  projects 
into  the  antral  cavity.  The  antero- external  wall  is  formed  by  the 
facial  surface,  and  is  thin  and  translucent  over  the  region  of  the 
canine  fossa.  It  contains  the  anterior,  and  the  lower  part  of  the 
middle,  dental  canals.  The  postero- external  wall  is  formed  by  the 
zygomatic  surface,  and  it  contains  the  upper  part  of  the  middle 
dental  canal.  The  opening  of  the  antrum,  which  is  large  and 
irregular,  is  situated  on  the  base  or  nasal  aspect.     In  the  articu- 


THE  BONES  OF  THE  HEAD  loi 

lated  skull  its  size  is  considerably  diminished  by  the  perpendicular 
plate  of  the  palate  bone  behind,  the  maxillary  process  of  the  in- 
ferior turbinate  below,  and  above  this  by  the  uncinate  process  of 
the  ethmoid.  The  opening  is  further  curtailed  by  the  adjacent 
mucous  membrane.  Under  these  circumstances  it  is  reduced  to 
a  small  aperture,  situated  near  the  upper  part,  which  opens  into  the 
middle  meatus  of  the  nasal  fossa  The  antrum  is  usually  uni- 
locular, but  it  may  be  partially  divided  into  compartments. 

The  bone  derives  its  blood  -  supply  from  many  sources,  such 
as  posterior  .dental,  infra-orbital,  middle  and  anterior  dental, 
facial,  frontal,  superior  or  descending  palatine,  and  naso-palatine 
arteries. 

Articulations. — The  superior  maxilla  articulates  with  nine  bones, 
as  follows:  malar,  nasal,  frontal,  lachrymal,  ethmoid,  inferior 
turbinate,  palate,  vomer,  and  its  fellow  of  the  opposite  side.  In 
addition  to  these  it  may  articulate  with  the  pterygoid  process  and 
great  wing  of  the  sphenoid. 


Fig.  62. — The  Foetal  Superior  Maxillary  Bone. 

A,  External  View,  showing  the  Infra-orbital  Groove  and  Foramen,  with 
Fissure  ;  B,  Inferior  View,  showing  the  Incisor  Fissure  and  Alveoli ; 
C,  Internal  View,  showing  the  Antrum  and  Incisor  Fissure. 


Structure. — The  bone  contains  the  maxillary  air  sinus.  For  the 
most  part  cancellated  tissue  is  absent,  except  in  the  alveolar  process 
around  the  alveoli. 

Ossification. — The  superior  maxillary  bone  is  ossified  in  membrane.  Accord- 
ing to  -Mall  and  Fawcett  it  has  two  centres— maxillary  proper  and  premaxillary, 
which  appear  about  the  sixth  week,  and  join  about  the  third  mouth.  The 
centre  referred  to  as  maxillary  proper  appears  in  the  region  of  the  future 
canine  alveolus,  and  from  it  ossification  proceeds  backwards  into  the  malar 
process,  upwards  into  the  posterior  half  of  the  nasal  process,  inwards  into 
the  posterior  three-quarters  of  the  palatal  process,  and  downwards  into  the 
alveolar  border,  excluding  the  incisor  portion. 

The  premaxillary  centre  gives  rise  to  the  premaxilla,  which  lies  on  the  mesial 
side  of  the  maxilla  proper  and  bears  the  upper  incisor  teeth.  It  also  gives 
rise  to  (i)  ihz  anterior  fourth  of  the  palatal  plate,  and  (2),  according  to  Fawcett, 
the  anterior  half  of  the  nasal  process.  It  is  to  be  noted  that,  whilst  the 
anterior  half  of  the  nasal  process  is  ossified  from  the  premaxillary  centre,  the 
posterior  half  oi  that  process  (bearing  the  lachyrmal  groove)  is  ossified  from  the 
maxillary  proper  centre. 

Besides  the  premaxillary  centre  there  is  an  infravomerine  centre,  according 
to  Rambaud  and  Renault.  This  centre  lies  beneath  the  anterior  part  of  the 
vomer,  and  it  gives  rise  to  the  infravomerine  part  of  the  bone,  which  forms 
the  mesial  wall  of  Stensen's  canal.     The  line  of  union  between  the  premaxilla 


I02  A  MANUAL  OF  ANATOMY 

and  maxilla  proper  is  indicated  by  the  premaxillary  suture  on  the  palatal 
surface  of  young  bones,  which  may,  though  somewhat  rarely,  persist  in  adult 
life.  This  suture  extends  outwards  and  forwards  from  a  point  directly  behind 
the  lower  end  of  Stensen's  canal  to  the  alveolar  border  between  the  lateral 
incisor  and  canine  alveoli. 

The  premaxilla  of  each  side  forms  an  independent  bone  in  many  animals. 
It  may  be  developed  in  two  parts  from  separate  centres  of  ossification — an 
inner  for  the  portion  bearing  the  central  incisor  alveolus,  and  an  outer  for 
the  portion  containing  the  lateral  incisor  alveolus,  and  these  two  portions  may 
remain  separate.  The  inner  portion  is  known  as  the  endognathion,  and  the 
outer  portion  as  the  niesognathion,  -whilst  the  remainder  and  greater  part  of 
the  bone  is  referred  to  as  the  maxilla  proper. 

The  varieties  of  alveolar  cleft  palate  are  explained  by' a  reference  to 
these  conditions  of  the  bone.  In  mesial  cleft  palate  the  two  premaxillae 
(right  and  left)  are  separated  by  a  mesial  cleft.  Lateral  cleft  palate  may 
occur  in  two  forms — the  maxilla  proper  or  excgnathion  and  the  entire 
premaxilla  may  fail  to  unite,  and  the  cleft  is  situated  between  them,  and 
invades  the  alveolar  border  between  the  lateral  incisor  and  canine  alveoli ;  or 
the  premaxilla  may  exist  in  two  parts,  inner  or  endognathion,  and  outer  or 
mesognathion,  and  the  cleft  may  be  between  these  two,  in  which  case  it 
invades  the  alveolar  border  between  the  central  and  lateral  incisor  alveoli. 
These  conditions  may  occur  on  one  or  both  sides. 

In  the  earlier  stages  of  intra -uterine  life  there  is  no  trace  of  the  antrum,  and 
the  alveolar  border  lies  close  to  the  infra -orbital  border.  In  the  course  of  the 
fourth  month,  however,  the  antrum  makes  its  appearance  as  a  shallow  depres- 
sion on  the  inner  aspect  of  the  bone,  and,  as  this  increases,  it  gradually 
separates  the  orbital,  alveolar,  and  palatal  portions.  In  the  process  of 
development  the  alveolar  border  first  presents  an  elongated  furrow,  called  the 
dental  groove,  on  either  side  of  which  a  plate  grows  downwards,  forming 
the  labial  and  lingual  plates.  The  groove  is  thus  converted  into  a  trench  with 
these  ramparts  on  either  side.  Subsequently  these  plates  are  connected  by  a 
number  of  septa,  which  intersect  the  trench  and  break  it  up  into  alveoli.  At 
this  stage  these  are  only  five  in  number  for  each  bone,  and  the  canine  alveolus 
is  the  first  to  be  partitioned  off.  In  early  life  the  bone  contains  the  temporary 
teeth,  which  are  five  in  number  on  either  side,  but  in  the  adult,  as  stated,  it 
contains  eight  alveoli  for  the  eight  permanent  teeth. 

The  Malar  Bones. 

The  malar  or  cheek-bone  is  situated  between  the  external 
angular  process  of  the  frontal  and  zygoma  of  the  temporal  on  the 
one  hand,  and  the  malar  process  of  the  superior  maxilla  on  the 
other,  where  it  separates  the  orbit  from  the  temporal  fossa.  It  is 
quadrilateral,  and  presents  two  surfaces,  four  processes,  and  four 
borders.  The  external  surface  is  convex,  and  near  its  centre  there 
is  the  malar  tuberosity.  Above  this  is  the  malar  foramen  for  the 
passage  of  the  malar  branch  of  the  temporo-malar  or  orbital 
nerve,  and  a  branch  of  the  lachrymal  artery.  The  portion  of  this 
surface  close  to  the  zygomatic  process  gives  origin  to  the  zygo- 
maticus  major,  and  the  lower  and  anterior  part  to  the  zygomaticus 
minor.  The  internal  surface,  which  is  concave,  looks  into  the 
temporal  fossa  above  and  zygomatic  fossa  below,  and  it  is  overhung 
superiorly  by  a  curved  plate  of  bone,  called  the  orbital  process. 
Anteriorly  it  presents  a  rough,  slightly  serrated,  triangular  area 
for  the  malar  process  of  the  superior  maxilla.  The  orbital  process 
projects  backwards  and  inwards,  in  a  curved  manner,  from  the 


THE  BOXES  OF  THE  HEAD 


103 


upper  part  of  the  internal  surface  on  a  level  \vith  the  orbital  border. 
It  is  triangular,  and  its  superior  or  orbital  surface  presents  a  sweep- 
ing concavity,  which  enables  it  to  form  the  front  part  of  the  outer 
wall  of  the  orbit,  and  a  portion  of  the  floor.  This  surface  is  pierced 
by  one  or,  it  may  be,  two  openings.  If  there  is  one,  it  ultimately 
leads  to  two  canals — malar,  which  opens  on  the  external  surface, 
and  temporal,  which  opens  on  the  temporal  division  of  the  internal 
surface,  as  a  rule  near  the  frontal  process.  These  canals  transmit  the 
malar  and  temporal  branches  of  the  temporo-malar  or  orbital  nerve. 
If  there  are  two,  each  leads  to  its  own  canal.  The  inferior  surface 
of  the  orbital  process,  which  is  convex,  forms  the  anterior  part  of 
the  temporal  fossa.  The  rough  margin  of  the  process  articulates 
by  its  superior  part  with  the  anterior  border  or  malar  crest  of  the 


Frontal  Process  (Sup.  Ang.) 
Malar  Foramen '     ' 


Marginal  Proces; 
Temporal  Border 

Zygomatic  Process  (Post.  An  s.) 


Orbital  Border 


Masseteric  Border' 

Malar  Tuberosity         | 
Maxillarj'  Process  (Inf.  Ang.) 


Infra-orbital  Process 
(Ant.  Ang.) 


Maxillary  BLrder 

Fig.  63. — The  Right  M.a.lar  Bone  (External  View) 


great  wing  of  the  sphenoid,  and  below  with  a  part  of  the  orbital 
plate  of  the  superior  maxilla.  The  part  of  this  border  between  the 
sphenoidal  and  maxillary  portions  sometimes  closes  the  anterior 
and  outer  extremity  of  the  spheno-maxillary  fissure,  and  thus 
intervenes  between  the  great  wing  of  the  sphenoid  and  the  superior 
maxilla. 

The  processes  are  four  in  number — superior,  posterior,  inferior, 
and  anterior.  The  superior  or  frontal  process  is  stout  and  promi- 
nent. Its  direction  is  vertically  upwards,  and  it  terminates  in 
a  thick  serrated  extremity  for  tlie  external  angular  process  of  the 
frontal.  The  posterior  or  zygomatic  process  is  short  and  usually 
blunt.  Its  direction  is  backwards,  and  it  terminates  in  a  serrated 
extremity  for  the  zygoma  of  the  temporal.  The  inferior  or  maxillary 
process  ia  blunt  and  truncated.     Its  direction  is  downwards,  and 


I04 


A  MANUAL  OF  ANATOMY 


it  articulates  with  part  of  the  malar  process  of  the  superior  maxilla. 
The  anterior  or  infra-orWtal  process  is  slender  and  pointed.  Its 
direction  is  forwards,  and  it  articulates  with  the  superior  maxilla 
near  the  infra-orbital  foramen. 

The  borders  are  four  in  number — temporal,  m.asseteric,  maxillary, 
and  orbital.  The  temporal  border  extends  from  the  frontal  process 
to  the  zygomatic,  and  is  directed  backwards.  It  is  sinuous,  and 
continuous  with  the  upper  border  of  the  zygoma,  and  it  gives 
attachment  to  the  temporal  fascia.  Near  the  frontal  process 
it  '  usually  presents  a  slight  prominence,  called  the  marginal 
process,  to  which  a  stout  sHp  of  the  temporal  fascia  is  attached. 
The  masseteric  border  extends  from  the  zygomatic  process  to  the 
maxiUary  process,  and  looks  downwards.  It  is  thick,  rough,  and 
continuous  with  the  lower  border  of  the  zygoma,  and  it  gives  origin 

Frontal  Process 

I        bital  Surface  of  Orbital  Process 

Opening  of  Temporal  Canal 
©>,   Opening  of  Malar  Canal 


Zygomatic  Process 


'         I  Temporo-Zygomatic  Surface 

I  ]         Maxillary  Process 

Infra-orbital  Process        For  Sup.  Maxilla 

Fig.  64. — The  Right  Malar  Bone  (Internal  View). 

to  the  anterior  fibres  of  the  superficial  part  of  the  masseter.  The 
maxillary  border  extends  from  the  maxillary  process  to  the  infra- 
orbital process,  and  it  looks  forwards  and  slightly  downwards.  It 
is  rough  and  slightly  concave,  and,  together  with  the  rough,  slightly 
serrated,  triangular  area  on  the  internal  surface  adjacent  to  it, 
articulates  with  the  malar  process  of  the  superior  maxilla.  The 
orbital  border  extends  from  the  infra-orbital  process  to  the  frontal, 
and  is  smooth,  round,  and  concave.  Its  direction  is  outwards  and 
upwards,  and  it  forms  a  large  part  of  the  circumference  of  the  orbit. 

The  bone  derives  its  blood-supply  from  the  lachrymal,  anterior 
deep  temporal,  and  transverse  facial  arteries. 

Articulations.- — The  malar  articulates  with  four  bones,  as  follows: 
superiorly  with  the  frontal  and  sphenoid,  posteriorly  with  the  tem- 
poral, and  anteriorly  with  the  superior  maxilla. 

Structure. — The  bone  is  mainly  composed  of  compact  tissue,  the 
amount  of  cancellated  tissue  being  small. 


THE  BONES  OF  THE  HEAD 


105 


Varieties. — The  bone  may  persist  in  two  parts  connected  by  a  suture,  which 
may  be  horizontal  or  vertical.     It  sometimes  persists  in  three  parts. 

Ossification. — ^The  malar  is  developed  in  membrane  from  three  centres, 
which  appear  in  the  eighth  week  of  intra-uterine  life,  and  they  unite  at  the 
end  of  the  foiitth  month.  These  centres  are  called  premalar,  postmalar,  and 
hypomalar.  If  all  three  centres  should  fail  to  unite,  then  a  tripartite  malar 
is  the  result.  If  the  premalar  and  postmalar  unite,  and  the  hypomalar  remains 
separate,  a  bipartite  malar  persists  with  a  horizontal  suture.  If  the  postmalar 
and  hypomalar  unite,  and  the  premalar  remains  separate,  the  suture  is  vertical. 
A  bipartite  malar  occurs  with  great  frequentcy  amongst  the  Japanese,  and 
from  this  circumstance  the  bone  is  known  as  the  OS  Japonicum. 


•  iSuperior  Border 


The  Nasal  Bones. 

The  nasal  bone,  which  articulates  with  its  fellow  by  its  mesial 
border,  forms  with  it  the  bridge  of  the  nose.  It  lies  in  front  of 
the  nasal  process  of  the  superior  maxilla,  where  it  enters  into  the 
formation  of  the  face  and  nasal  fossa.  The  bone  is  elongated  from 
above  downwards,  and  presents  two  sur- 
faces and  four  borders.  The  anterior  or 
facial  surface  is  smooth,  concavo-convex 
from  above  downwards,  and  convex  from 
side  to  side.  Near  its  centre  it  usually 
presents  a  minute  foramen  for  the  passage 
of  a  small  vein  from  the  nose  to  the  com- 
mencement of  the  facial  vein.  This  surface 
supports  the  common  aponeurosis  of  the 
pyramidalis  nasi  and  compressor  naris 
muscles.  The  posterior  or  na'^al  surface  is 
rough  superiorh^  where  it  articulates  with 
the  nasal  process  of  the  frontal.  Elsewhere 
it  is  smooth  and  concave  from  side  to  side, 
and  in  the  recent  state  is  covered  by  the 
nasal  mucous  membrane.  It  is  traversed 
longitudinally  near  the  centre  by  the  nasal 
groove  for  the  nasal  nerve. 

The  superior  horcLpr  is  short,  thick, 
and  serrated  for  the  nasal  notch  of  the 
frontal.  The  inferior  border  is  thin  and  ex- 
panded for  the  upper  lateral  nasal  cartilage. 
It  usually  presents  the  nasal  notch,  which 
is  situated  near  its  inner  end.  The  mesial 
border  articulates  with  its  fellow.  It  is 
usually  rather  shorter  and  thicker  than  the 
external,  and  projecting  backwards  from  it 
is  a  ledge  of  Ijon'-,  which,  with  its  fellow, 
forms  the  nasal  crest  for  articulation  with 

frontal  and  the  anterior  bfjrder  of  the  perpendicular  plate  of  the 
ethmoid  The  external  border,  long  and  thin,  is  finely  serrated  for 
the  nasal  process  of  the  superior  maxilla. 


ilesial  Border 


~| >JasaI  Notch 


•'inferior  B 


-•Nasal  Crest 


•Nasal  Groov 


Fig.  65. — The  Right 
Nasal  Bone. 

A,  Anterior  View;  B,  Pos- 
terior View. 

the  nasal  spine  of  the 


io6  A  MANUAL  OF  ANATOMY 

The  bone  receives  its  blood-supply  from  the  angular  branch,  of 
the  facial,  and  the  nasal  and  anterior  ethmoidal  branches  of  the 
ophthalmic,  arteries. 

Articulations.— The  nasal  articulates  with  four  bones,  as  follows  : 
superiorly  with  the  frontal,  externally  with  the  superior  maxilla, 
internally  with  its  fellow,  and  posteriorly  with  the  ethmoid  and  again 
with  the  frontal. 

Structure. — The  bone  is  composed  of  compact  tissue,  and  is  there- 
fore dense. 

Ossiflcation. — The  nasal  is  developed  in  membrane  from  one  centre,  which 
appears  about  the  eighth  week  of  intra-uterine  life. 

The  Lachrymal  Bones. 

The  lachrymal  or  tear-bone  is  situated  at  the  anterior  part  of  the 
inner  wall  of  the  orbit,  where  it  lies  behind  the  nasal  process  of  the 
superior  maxilla,  and  in  front  of  the  os  planum  of  the  ethmoid.  It 
is  very  thin  and  scale-like.  From  its  resemblance  in  this  sense 
to  a  finger-nail,  it  is  known  as  the  os  itnguis.  It  is  quadrilateral 
and  presents  two  surfaces  and  four  borders,  the  inferior  border 
being  recognised  by  its  presenting  a  hamular  and  a  descending  pro- 
cess. The  external  or  orbital  surface  is  traversed  by  the  lachrymal 
crest,  which  is  nearer  the  anterior  than  the  posterior  border,  and 

divides  the  surface  into  two  unequal 
Superior  Border  parts.     The  auterior  division,  represent- 

ing  one-third,    presents   the   lachrymal 
groove,  which  lodges  the  lachrymal  sac 
Anterior  Border         and    the    commcnccment    of   the    nasal 

Lachrymal  Groove         duct.       The  loWCr  CUd    of   th^S   divisiOU  is 

.  Orbital  Surface         prolougcd  iuto  the  desccnding  process, 

Hamular  Process       which  takcs  part  iu  the  wall  of  the  lach- 
j__  Descending  Process    j-ymal  caual,   and   articulates  with   the 
■p      fi^     T      T?          T  lachrymal    process   of   the  inferior  tur- 

'""■RYMTLBoNETExTERNrL    ^inate.      Thc   />os/mo/    division     vepre- 
View).  sentmg  two-thirds,  is  smooth  and  forms 

part  of  the  inner  wall  of  the  orbit.  The 
iashrymal  crest  gives  origin  to  the  tensor  tarsi  muscle,  and 
interiorly  terminates  in  a  hook-Hke  projection,  called  the  hamular 
process.  This  process  is  curved  in  a  forward  direction,  and  is 
received  into  the  lachrymal  notch  at  the  front  part  of  the  internal 
border  of  the  orbital  plate  of  the  superior  maxilla,  where  it 
bounds  externally  the  superior  oriiice  of  the  lachrymal  canal.  It 
articulates  with  the  lachrymal  tubercle  of  the  superior  maxilla. 
The  internal  surface  presents  a  vertical  furrow  corresponding  with 
the  position  of  the  lachrymal  crest  on  the  external  surface. 
Superiorly  it  articulates  with  the  front  part  of  the  lateral  mass 
of  the  ethmoid,  where  it  helps  to  close  ethmoidal  cells,  and  forms 
part  of  the  infundibulum.  Interiorly  it  forms  part  of  the  outer 
wall  of  the  nasal  fossa,  and  looks  into  the  middle  meatus. 


THE  BONES  OF  THE  HEAD  107 

The  superior  border  is  short,  and  articulates  with  the  internal 
angular  process  of  the  frontal.  The  inferior  border,  behind  the 
lachrymal  crest,  articulates  with  the  internal  border  of  the  orbital 
surface  of  the  superior  maxilla,  whilst  in  front  of  the  crest  it  forms, 
as  stated,  the  descending  process,  and  articulates  with  the  lachrymal 
process  of  the  inferior  turbinate.  The  anterior  border  articulates 
with  the  inner  lip  of  the  lachrymal  groove  on  the  posterior  border 
of  the  nasal  process  of  the  superior  maxilla.  The  posterior  border 
articulates  with  the  anterior  border  of  the  os  planum  of  the  ethmoid. 

The  bone  derives  its  blood-supply  from  the  nasal  and  anterior 
ethmoidal  branches  of  the  ophthalmic  artery. 

Articulations. — The  lachrymal  articulates  with  four  bones,  as 
follows  :  superiorly  with  the  frontal,  anteriorly  with  the  superior 
maxilla,  inferiorlv  with  the  inferior  turbinate,  and  again  with  the 
superior  maxilla,  and  posteriorly  with  the  ethmoid. 

Structure. — The  bone  consists  of  a  thin  translucent  plate. 

Ossification. — The  lachrymal  is  developed  in  membrane  usually  from  one 
centre,  which  appears  during  the  third  month  of  intra-uterine  life.  It  may, 
however,  have  two  or  more  centres. 


The  Inferior  Turbinate  Bones. 

The  inferior  turbinate  or  spongy  bone  (maxillo-turbinal)  some- 
times called  the  inferior  concha,  is  situated  on  the  outer  wall  of  the 


Lachrymal  Proce>-s 


Front  Part  of  .Superior. 
Border 


Anterior  Extremity . 


Ethmoidal  Process 

1 

Back  Part  of  Superior  Border 


Inferior  Border 


Ethmoidal  Process 

Maxillary  Process 


Lachrymal  Process 


..Anterior 
JOxlrLinity 


Inferior  Border 

Fig.  67. — The  Right  Inferior  Turbinate  Bone. 
A,  Internal  View  ;  B,  External  View. 

nasal  fossa,  where  it  overhangs  the  inferior  meatus,  and  is  in  series 
with  the  inferior  turbinate  jirocess  (middle  spongy  bone)  of  the 
ethmoid.     It   is  olongat(;d    from   Ixiforc;   backwards,   and   ]iresents 


io8  A   MANUAL  OF  ANATOMY 

two  surfaces,  two  borders,  and,  two  extremities.  The  external 
surface  is  concave,  and  is  overhung  above,  over  about  its  middle 
third,  by  the  maxihary  process.  It  looks  towards  the  outer  wall 
of  the  nasal  fossa.  The  internal  surface  is  irregularly  convex, 
pitted,  and  marked  by  a  few  antero-posterior  grooves.  It  bulges 
into  the  nasal  fossa,  and  limits  interiorly  the  middle  meatus. 

The  IsHpe/ioy  border,  which  is  attached,  slopes  downwards  and 
forwards  in  front,  where  it  articulates  with  the  inferior  turbinate 
crest  of  the  superior  maxilla.  Behind  this  it  presents  a  slight 
concavity,  limited  in  front  by  the  lachrymal  process,  which  articu- 
lates with  the  descending  process  of  the  lachrymal,  and  forms  part 
of  the  lachrymal  canal.  Behind  the  concavity  is  the  ethmoidal 
process  for  the  uncinate  process  of  the  ethmoid.  The  portion  of 
the  superior  border  between  these  two  processes  is  folded  down- 
wards and  outwards  into  a  thin  plate,  called  the  maxillary  process, 
which  forms  part  of  the  inner  wall  of  the  antrum  of  Highmore 
below  the  opening  of  that  cavity.  Behind  the  ethmoidal  process 
the  superior  border  slopes  downwards  and  backwards,  and  articu- 
lates with  the  inferior  turbinate  crest  of  the  palate  bone.  The 
inferior  border  is  convex,  thick,  pitted,  and  free.  The  anterior 
extremity  is  short  and  stunted,  whilst  the  posterior  is  long,  slender, 
and  pointed. 

The  bone  receives  its  blood-supply  from  the  spheno-palatine 
branch  of  the  internal  maxillary,  and  anterior  ethmoidal  branch 
of  the  ophthalmic,  arteries. 

Articulations. — The  inferior  turbinate  articulates  with  the  follow- 
ing four  bones  :  superior  maxilla,  lachrymal,  ethmoid,  and  palate. 

Structure. — The  bone  is  light  and  porous. 

Ossification. — The  inferior  turbinate  is  developed  in  cartilage  from  one 
centre,  which  appears  in  the  pfth  month  oi  intra-u ferine  Ufe. 

The  Palate  Bones. 

The  palate  bone  enters  into  the  formation  of  the  hard  palate, 
the  outer  wall  of  the  nasal  fossa,  and  the  floor  of  the  orbit.  It 
consists  of  a  horizontal  and  perpendicular  plate,  which  meet  at  a 
right  angle,  and  of  three  processes,  namely,  pyramidal  process 
or  tuberosity,  situated  at  the  meeting  of  the  two  plates  posteriorly, 
and  orbital  and  sphenoidal  processes,  situated  at  the  upper  ex- 
tremity of  the  perpendicular  plate,  where  they  are  separated  by 
the  spheno-palatine  notch. 

The  horizontal  or  palatal  plate  is  quadrate,  and  presents  two 
surfaces  and  four  borders.  The  superior  or  nasal  surface  is  smooth 
and  concave  from  side  to  side.  It  forms  the  posterior  fourth  of  the 
floor  of  the  nasal  fossa,  and  is  covered  in  the  recent  state  by  the  nasal 
mucous  membrane.  The  inferior  or  palatal  surface  forms  the  pos- 
terior fourth  of  one-half  of  the  hard  palate,  and  near  its  posterior 
border  it  presents  a  short  transverse  ridge,  which  gives  insertion  to 
a  portion  of  the  tendon  of  the  tensor  palati.    The  anterior  border 


THE  BONES  OF  THE  HEAD  109 

is  serrated  for  the  posterior  border  of  the  palatal  process  of  the 
superior  maxilla.  The  posterior  border  is  concave  and  sharp.  It 
gives  attachment  to  one-half  of  the  soft  palate,  and  at  its  inner 
extremity  it  forms  a  backward  projection,  which,  with  its  fellow, 
constitutes  the  palatal  or  posterior  nasa!  spine,  for  the  attachment 
of  the  azygos  uvulae  muscle.  The  external  border  is  attached, 
and  meets  the  perpendicular  plate  at  a  right  angle.  On  its  outer 
aspect  posteriorly  it  is  excavated  by  the  lower  part  of  the  posterior 
palatine  canal.  The  internal  border  is  thick  and  serrated,  and 
articulates  with  its  fellow,  forming  an  upward  elevation,  called  the 
nasal  crest.  This  crest  is  continuous  with  that  of  the  palatal 
processes  of  the  superior  maxillae,  and,  like  it,  is  grooved  superiorly 
for  a  portion  of  the  inferior  border  of  the  vomer. 

The  perpendicular  plate   rises  upwards  from  the  outer  border 
of  the  horizontal  plate.     It  is  long  and  thin,  and  presents  two 

Internal  or  Ethmoidal  Siirf.^^  /T^ Sup.  or  Orbit.  Surf,  of  Oibital  Process 

,         .  ii»     -n         c-     r  h-mimr Posterior  Or  Sphenoidal  Surface 

Anterior  or  Maxillary  Surf.-^    -/  W^fM 

Spheno-palatine  Notch  ._  ir^^^L    £Vj^,Sphenoidal  Process 

Superior  Turbinate  or 

Ethmoidal  Crest  /-^l"  '■■W')l|i|lllN,'''''W~"~""- Superior  Meatus 


Maxillary  Process  _ 


--  Middle  Meatus 

.  -  Inferior  Turbinate  Crest 


Inferior  Meatus 
For  Pterygoid  Fossa  of  Sphenoid 
_  For  Ext.  Pterygoid  Plate 
of  .Sphenoid 


Nasal  Crest  |        ^         Tuberosity 

Posterior  Nasal  .Spine        For  Int.  Pterygoid  Plate  of  Sphenoid 

Fig.  68. — The  Right  Palate  Bone  (Internal  View). 

surfaces  and  four  borders.  The  internal  surface  forms  part  of  the 
outer  wall  of  the  nasal  fossa,  and  is  crossed  from  before  backwards 
by  two  ridges.  The  lower  ridge  is  called  the  inferior  turbinate  crest, 
and  articulates  with  the  posterior  sloping  part  of  the  superior 
border  of  the  inferior  turbinate  bone.  The  upper  ridge,  which 
crosses  the  roots  of  the  orbital  and  sphenoidal  processes,  is  called 
the  ethmoidal  or  superior  turbinate  crest,  and  it  articulates  with  the 
inferior  turbinate  ])rocess  of  the  ethmoid.  Below  the  inferior 
turbinate  crest  is  a  smooth  groove,  which  forms  part  of  the  inferior 
meatus  of  the  nose ;  between  the  inferior  and  superior  turbinate 
crests  is  another  groove,  which  forms  part  of  the  middle  meatus ; 
and  above  the  superior  turbinate  crest  there  is  a  third  groove, 
which  forms  part  of  the  superior  meatus.  The  external  or  maxillary 
surface,  towards  its  upper  and  posterior  part,  forms  the  inner 
boundary  of  the  i)terygo-maxillary  fissure,  and  leading  downwards 
from  this  part  is  a  groove,  which,  with  the  superior  maxilla,  forms 


A  MANUAL  OF  ANATOMY 


the  posterior  palatine  or  palato-maxillary  canal  for  the  great  or 
anterior  descending  palatine  nerve  and  the  superior  or  descending 
palatine  artery.  In  front  of  this  groove  the  external  surface 
articulates  with  the  inner  surface  of  the  superior  maxilla  behind 
the  opening  of  the  antrum.  Behind  the  groove  the  external  surface 
articulates  interiorly  with  the  posterior  border  of  the  superior 
maxiUa,  and  superiorly  with  the  internal  pterygoid  plate  of  the 
sphenoid. 

The  anterior  border  of  the  perpendicular  plate  presents,  just 
below  the  inferior  turbinate  crest,  a  leaf- like  projection,  called  the 
maxillary  process,  which  closes  the  lower  and  back  part  of  the 
opening  of  the  antrum  of  Highmore.  Superiorly  it  articulates  with 
the  ethmoid,  and  interiorly  with  the  superior  maxilla.  The  pos- 
terior border  articulates  superiorly  with  the  anterior  border  of 
the  internal  pterygoid   plate    of   the   sphenoid,  and   inferiorly  it 


Spheno-maxillary  Surfacesj.^^ 
Sphenoidal  Process.^ 


Inner  Boundary  of 
Pterj'go-ma.xillary  Fissure 


.Orbital  Process 

.  -Spheno-palatine  Notch 


"'^  For  Superior  Maxilla 


Maxillary  Process 
for  Maxillary  Sinus 


Tuberosity      [  j       Groove  for  Post.  Palatine  Canal 

For  Zygomatic  Fossa  For  Post.  Border  of  Sup.  Maxilla 

Fig.  69. — The  Right  Palate  Bone  (External  View). 

is  prolonged  into  the  tuberosity.  The  inferior  border  is  attached, 
and  meets  the  horizontal  plate.  The  superior  border  presents  the 
orbital  and  sphenoidal  processes  and  the  spheno-palatine  notch,  to 
be  presently  described. 

The  pyramidal  process  or  tuberosity  projects  backwards,  down- 
wards, and  outwards  from  the  meeting  of  the  horizontal  and  per- 
pendicular plates,  and  is  received  into  the  pterygoid  notch  of  the 
sphenoid.  Posteriorly  it  presents  three  grooves.  The  central 
groove  forms  part  of  the  pterygoid  fossa,  and  gives  origin  to 
fibres  of  the  internal  pterygoid.  The  grooves  on  either  side  are 
rough,  and  articulate  with  the  anterior  borders  of  the  correspond- 
ing pterygoid  plates.  The  tuberosity  on  its  inferior  aspect,  close 
to  the  horizontal  plate,  presents  two  small  openings,  which  are 
the  orifices  of  the  posterior  and  external  accessory  palatine  canals, 
the  latter  being  the  smaller  of  the  two,  and  inconstant.  These 
canals   transmit  the   posterior   and   external   descending  palatine 


THE  BONES  OF  THE  HEAD  iii 

nerves  and  arteries.  Internally  the  tuberosity  gives  origin  to  a 
few  fibres  of  the  superior  constrictor  muscle  of  the  pharynx. 
Externally  there  is  a  small  free  surface,  which  looks  into  the 
zygomatic  fossa,  between  the  pterygoid  process  of  the  sphenoid 
and  the  tuberosit}'  of  the  superior  maxilla. 

The  orbital  process  surmounts  the  anterior  border  of  the  per- 
pendicular plate.  It  is  of  large  size,  and  presents  six  surfaces, 
three  of  which  are  articular.  The  superior  or  orbital  surface  forms 
a  small  part  of  the  floor  of  the  orbit  posteriorly.  The  external 
or  spheiio- maxillary  surface  looks  into  the  spheno-maxillary  fossa. 
The  anterior  or  maxillary  surface  is  continuous  with  the  external 
surface  of  the  perpendicular  plate,  and  articulates  with  the  back 
part  of  the  internal  border  ot  the  orbital  surface  of  the  superior 
maxilla.  The  iniernal  or  ethmoidal  surface,  which  is  excavated, 
aiticulates    with    the    lower    border    of    the    os    planum    of    the 

Post,  or  Sphenoidal  Surf,  of  Orbital  Proces-;,  /  .^:uperior  or  Orbital  Surface 

Superior  or  Sphenoidal  Surface.^  [Vm  I'llii 

of  Sphenoidal  Process  '■■-,         I'SJM^    ^     .Kxt.  or  Spheno-maxillary 


Groove  for  Pterygopalatine  Canal  —  ''' 

Inferior  Turbinate  Crest 

Nasal  Crest- -i-\ 


Surface 

"-»S{heno-palatine  Notch 

.-Groove  for  Post.  Palatine  Canal 
(on  Ext.  Surf.) 

_  For  Pterygoid  Fossa  of  Sphenoid 


j  ^^~"l?\W^'iJ\ For  Ext.  Pterygoid  Plate 

Posterior  Nasal  Spine .'  /  ^^>S^H^  °^  Sphenoid 

Horizontal  Plate'  /  7^ 

For  Int.  Pterygoid  Plate  of  Sphenoid  '  ^J 

Tuberosity 

Fig.  70. — The  Right  Palate  Bone  (Posterior  View). 

ethmoid  at  its  back  part,  close  to  the  postero-inferior  angle.  The 
posterior  or  sphenoidal  surface,  small  and  excavated,  articulates 
with  the  front  of  the  body  of  the  sphenoid,  and,  as  a  rule,  com- 
municates with  the  sphenoidal  air  sinus.  The  inferior  or  n:.sal 
surface  is  continuous  with  the  internal  surface  of  the  perpendicular 
plate,  and  forms  part  of  the  outer  wall  of  the  nasal  fossa  at  its 
upper  and  back  part,  wheie  it  overhangs  the  groove  for  the  superior 
meatus. 

The  sphenoidal  process  surmounts  the  posterior  border  of  the 
perpendicular  j)late,  and  is  slightly  incurved.  It  presents  three 
surfaces,  and  three  borders.  The  superior  or  sphenoidal  surface, 
which  IS  grooved,  articulates  with  the  inferior  surface  of  the  body, 
and  the  vaginal  process,  of  the  sphenoid.  The  groove  on  this 
surface,  with  that  on  the  under  surface  of  the  vaginal  process,  forms 
the  pterygo-palatine  canal  for  the  pharyngeal  nerve  and  pterygo- 
palatine artery.     The  internal  or  nasal  surface  is  scooped  out,  and 


112  A   MANUAL  OF  ANATOMY 

has  an  inclination  downwards  as  well  as  inwards.  It  forms  part 
of  the  outer  wall  and  roof  of  the  nasal  fossa  The  external  or 
spheno-maxillary  surface  forms  part  of  the  inner  wall  of  the  spheno- 
maxillary fossa.  The  anterior  border  bounds  the  spheno-palatine 
notch  posteriorly,  and  may  be  projected  over  it  to  join  the  orbital 
process.  The  posterior  border  articulates  with  the  internal  ptery- 
goid plate  of  the  sphenoid.  The  internal  border  articulates  with 
the  ala  of  the  vomer. 

The  spheno-palatine  notch  is  situated  between  the  orbital  and 
sphenoidal  processes,  and  is  converted  into  a  foramen  usually  by 
the  inferior  surface  of  the  body  of  the  sphenoid,  representing  the 
part  formed  by  a  sphenoidal  spongy  bone.  It  leads  from  the 
spheno-maxillary  fossa  into  the  superior  meatus  of  the  nose,  and 
transmits  the  internal  branches  of  the  spheno-palatine  or  Meckel's 
ganglion,  and  spheno-palatine  artery. 

The  bone  derives  its  blood-supply  from  the  spheno-palatine, 
descending  palatine,  and  pterygo-palatine  branches  of  the  internal 
maxillary  artery. 

Articulations. — The  palate  bone  articulates  with  six  bones,  as 
follows:  the  superior  maxilla,  inferior  turbinate,  ethmoid,  vomer, 
sphenoid,  and  its  fellow. 

Structure. — The  bone  is  very  thin,  especially  over  the  upper 
part  of  the  perpendicular  plate. 

Varieties. — (i)  The  groove  for  the  posterior  palatine  canal  may  be  bridged 
over.  (2)  The  external  accessory  palatine  canal  may  be  absent.  (3)  The 
spheno-palatine  notch  may  be  converted  into  a  foramen  by  a  forward 
extension  of  the  sphenoidal  process. 

Ossification. — The  palate  bone  is  ossified  in  membrane  from  one  primary 
centre.  The  primary  centre  appears  about  the  seventh  week,  at  the  angle  of 
junction  between  the  horizontal  and  vertical  plates,  or  in  the  vertical  plate 
(Fawcett).     There  may  be  a  secondary  centre  for  the  orbital  process. 

The  Vomer. 

The  vomer  is  situated  in  the  median  plane,  and  forms  part  of 
the  septum  of  the  nose.  It  presents  two  surfaces,  four  borders, 
and  an  anterior  extremity.  The  surfaces  are  disposed  laterally, 
and  each  looks  into  the  corresponding  nasal  fossa.  Traversing 
each  there  is  a  groove,  directed  forwards  and  downwards,  for  the 
naso-palatine  nerve. 

The  superior  border  is  characterized  by  two  thick,  everted  alse, 
separated  by  a  groove,  which  receives  the  rostrum  of  the  sphenoid. 
Each  ala  by  its  upper  aspect  fits  against  the  inferior  surface  of 
the  body  of  the  sphenoid,  and  the  lateral  margin  of  each  meets 
the  vaginal  process  of  that  bone,  and  also  articulates  with  the 
internal  border  of  the  sphenoidal  process  of  the  palate  bone.  The 
inferior  border  is  irregular,  and  is  received  into  the  groove  which 
marks  the  nasal  crests  of  the  palatal  plates  of  the  superior  maxillae 
and  palate  bones.     The  anterior  border  is  sloped  downwards  and 


THE  BONES  OF  THE  HEAD 


113 


forwards,  and  it  may  present  two  alae,  but  these  are  very  thin, 
and  lie  near  each  other,  being  separated  by  a  narrow  cleft.  These 
characters  are  always  more  pronounced  in  earlier  life.  The  cleft, 
in  its  lower  part,  receives  the  septal  nasal  cartilage,  and  superiorly 
the  perpendicular  plate  of  the  ethmoid  fits  into  it,  being  usually 
ankylosed  with  one  or  both  alae.  In  many  cases,  however,  the 
anterior  border  is  simply  grooved.  The  posterior  border  is  sharp, 
and  almost  vertical,  and  lies  between  the  posterior  nares.  The 
anterior  extremity  forms  a  short  irregular  lip,  which  touches  the 
back  parts  of  the  incisor  crests  of  the  superior  maxillae. 

The  bone  receives  its  blood-supply  from  the  spheno-palatine 
branch  of  the  internal  maxillary  artery. 

Articulations. — The  vomer  articulates  with  six  bones,  as  foUows  : 
the  sphenoid,  two  palate  bones,  ethmoid,  and  superior  maxillae. 
In  addition  to  these   it  articulates  with  the  septal  nasal  cartilage. 


Superior  Border 


Anterior  Border 


Posterior  Border 


Groove  for  Septal 
I  Nasal  Cartilage 


Anterior  Extremity 


Groove  for  Naso-palatine  Nerve 

Inferior  Border 

Fig.  71. — The  Vomer  (Lateral  View). 

Structure. — The  vomer  is  composed  of  two  thin  plates  of  compact 
bone,  which  are  blended  into  one,  except  superiorly,  and,  it  may 
be,  to  a  certain  extent  anteriorly. 

Varieties. — The  bone  is  often  much  deflected  to  one  or  other  side,  more 
frequently  the  left,  and  so  it  may  curtail  the  cavity  of  the  nasal  fossa  to 
which  it  is  deflected. 

Ossification. — The  vomer  is  developed  in  membrane  from  two  centres,  wliich 
appear  about  the  eif;hth  week  of  intra-u ferine  life.  The  centres  unite  below 
in  the  third  month,  and  form  a  groove  in  which  the  septal  nasal  cartilage  lies. 
The  lamina;  forming  the  lips  of  the  groove  continue  to  grow  upwards  and 
forwards,  and  subsequently  fuse,  the  enclosed  cartilage  becoming  absorbed. 
Ultimately  there  are  left  the  alae  on  the  superior  border,  and,  it  may  be,  on  the 
anterior  border,  which  are  permanent  indications  of  the  original  bilaminar 
condition  of  the  bone. 


The  Inferior  Maxillary  Bone. 

The  inferior  maxillary  bone  or  mandible  supports  the  lower  teeth, 
and  articulates  at  either  side  with  the  anterior  jmrt  of  the  glenoid 
fossa  of   the  temporal   in  a  freely  movable  manner.     It  has   the 

8 


114 


A  MANUAL  OF  ANATOMY 


shape  of  a  horse-shoe,  and  consists  of  a  central  horizontal  portion, 
called  the  body,  and  two  upright  portions,  called  the  rami. 

The  body  is  arched,  being  convex  in  front  and  concave  behind, 
and  it  presents  two  surfaces  and  two  borders.  The  external  surface 
presents  a  slight  median  vertical  ridge  over  its  upper  two-thirds, 
which  marks  the  symphysis  or  place  of  union  of  the  two  halves 
of  which  the  bone  is  originally  composed.  This  ridge  bifurcates  at 
the  lower  third,  and  its  two  divisions,  diverging,  pass  to  the  lower 
border,  where  each  terminates  in  the  mental  tubercle.  Between 
these  diverging  divisions   there   is   a  triangular   elevated  surface, 


Sigmoid  Notch 


Left  Coronoid  Process 
Temporal  Muscle 


External  Pterygoid 
Left  Condyle 


Impression  for  Temporal 
Muscle 


Incisor  Fossa 


Levator  Menti 
Depressor  Labii__ 
Inferioris 


Mental  Protuberance 

Mental  Tubercle 


Posterior 
--Border  of  Ramus 
Masseter 


Base 
Platysma  Myoides 
External  Oblique  Line  and 
Depressor  Anguli  Oris 


Mental  Foramen 

Fig.  72. — The  Inferior  Maxillary  Bone  (External  View). 

called  the  mental  protuberance  or  chin.  On  either  side  of  the  sym- 
physis is  the  incisor  fossa,  which  gives  origin  to  the  levator  menti 
and  a  deep  slip  of  the  orbicularis  oris.  A  little  external  to  this 
fossa  is  the  mental  foramen,  which  opens  outwards  from  the  inferior 
dental  canal,  and  transmits  the  mental  nerve  and  vessels.  This 
foramen  is  in  line  with  the  septum  between  the  two  bicuspid  alveoli, 
and  in  the  adult  it  is  midway  between  the  superior  and  inferior 
borders.  Below  it  is  the  external  oblique  line,  which  extends  from 
the  mental  tubercle  to  the  lower  extremity  of  the  anterior  border 
of  the  ramus.  This  line  gives  origin  to  the  depressor  anguli  oris. 
The  lower  part  of  the  external  surface,  from  near  the  symphysis 
to  about  the  level  of  the  mental  foramen,  gives  origin  to  the  depressor 
labii  inferioris. 


THE  BONES  OF  THE  HEAD 


•15 


The  internal  surface  presents  a  slight  median  groove  over  about 
its  upper  two-thirds,  which  coincides  with  the  symphysis.  Lower 
down  there  are  four  small  projections,  called  collectively  the  genial 
spines,  which  are  arranged  in  pairs  on  either  side  of  the  middle  line. 
The  upper  spine  gives  origin,  at  either  side,  to  the  genio-hyo- 
glossus,  and  the  lower  to  the  genio-hyoid.  Close  to  the  lower  border, 
at  either  side  of  the  symphysis,  is  the  oval  digastric  impression, 
which  gives  origin  to  the  anterior  belly  of  the  digastric.  Coin- 
ciding with  the  position  of  the  external  oblique  line  there  is  the 


_  Condyle 


Coronoid  Process 
Temporal  Muscle 
Liiigula 


,Inferior  Dental  Foramen 
^Buccinator 

,  ^  Fossa  for  Submaxillary  Gland 

/ 
/ 

''  Internal  Oblique  Line 

/  (Mylo-hyoid  Ridge) 

Fossa  for  Sublingual  Gland 


Angle  I 

I 

I 

Mylo-hyoid  Groove 


Upper  Genial 

Spine  and 

Genio-hyo-glossus 

_  Lower  Genial 

Spine  and 

Genio-hyoid 


Digastric  Impression  and 
Anterior  Belly  of  Digastric 

Fig.  73. — The  Lkft  Half  of  the  Inferior  Maxillary  Bone 
(Internal  View), 


internal  oblique  line  or  mylo-hyoid  ridge.  This  commences  near 
the  symphysis  below  the  lower  genial  spine,  and,  passing  obliquely 
backwards  and  upwards,  it  terminates  a  httle  behind  the  last  molar 
alveolus.  It  gives  origin  to  the  mylo-hyoid  muscle  over  its  whole 
length,  whilst  at  its  upper  and  back  part  it  gives  attachment  to 
some  fibres  of  the  superior  constrictor  muscle  of  the  pharynx  and 
the  pterygo-mandibular  ligament.  Below  the  posterior  part  of  this 
ridge  is  the  submaxillary  fossa  for  the  submaxillary  gland,  and  above 
its  anterior  part  is  the  sublingual  fossa  for  the  sublingual  gland. 
The  superior  or  alveolar  border  is  excavated  into  sixteen  alveoli 

8—2 


ii6  A   MANUAL   OF  ANATOMY 

Oi  sockets,  eight  in  each  half  of  the  bone,  which  correspond  with 
those  in  each  superior  maxilla.  The  outer  surface  of  the  alveolar 
border,  over  the  extent  of  the  three  molar  alveoli  at  either  side, 
gives  origin  to  some  fibres  of  the  buccinator.  The  inferior  border 
or  base  terminates,  at  either  side,  on  a  level  with  the  anterior 
border  of  the  ramus.  It  projects  more  than  the  superior  border, 
and  gives  insertion  on  its  outer  aspect  to  a  portion  of  the  platysma 
myoides.  Near  its  termination  it  is  marked  by  a  short  vertical 
groove  for  the  facial  artery. 

The  ramus  rises,  at  either  side,  from  the  extremity  of  the  body. 
It  is  compressed  from  without  inwards,  and  presents  two  surfaces 
and  four  borders.  The  external  surface  gives  insertion  to  the 
masseter,  and,  in  the  vicinity  of  the  angle,  it  presents  a  few  oblique 
ridges  for  the  tendinous  bands  of  that  muscle.  The  internal 
surface  presents,  a  little  below  its  centre,  the  inferior  dental  foramen, 
which  is  on  a  level  with  the  summit  of  the  crown  of  the  third  molar 
tooth.  This  foramen  leads  to  the  dental  canal,  which  traverses 
the  bone  to  near  the  symphysis,  and  from  which,  near  its  anterior 
part,  the  mental  foramen  opens  on  the  external  surface.  This 
canal  lodges  the  inferior  dental  nerve  and  vessels,  and  communicates 
with  the  foramina  which  open  on  the  extremities  of  the  fangs  of 
the  teeth.  The  inferior  dental  foramen  presents  anteriorly  and 
internally  a  thin,  sharp  plate  of  bone,  called  the  lingula.  Behind 
the  lower  end  of  the  latter  is  a  short  crescentic  margin  on  the  inner 
aspect  of  the  foramen,  and  proceeding  downwards  and  forwards 
from  this  is  the  mylo-hyoid  groove,  which  terminates  a  little  below 
the  posterior  extremity  of  the  mylo-hyoid  ridge,  and  transmits 
the  mylo-hyoid  nerve  and  artery.  The  spheno-mandibular  liga- 
ment is  attached  to  the  lingula  and  to  the  crescentic  margin  behind 
it.  Between  the  inferior  dental  foramen  and  the  angle  there  is  a 
rough  impression,  often  strongly  ridged,  which  gives  insertion  to 
the  internal  pterygoid. 

The  anterior  border  is  continuous  with  the  external  oblique  line 
opposite  the  third  molar  alveolus,  and  is  shorter  than  the  posterior. 
The  posterior  border  meets  the  inferior  border,  thus  forming  the 
angle,  which,  in  muscular  subjects,  is  strongly  marked  and  slightly 
everted.  Externally  and  internally  it  presents  rough  impressions 
for  portions  of  the  masseter  and  internal  pterygoid  respectively, 
and  between  these  muscles  it  gives  attachment  to  the  stylo-man- 
dibular  ligament.  The  angle  is  obtuse,  and  in  the  adult  amounts  on 
an  average  to  120  degrees.  In  early  infancy  it  is  as  much  as  150 
degrees,  and  in  old  age  it  amounts  to  about  140  degrees.  The 
inferior  border  is  continuous  with  the  inferior  border  or  base  of 
the  body.  The  superior  border  presents  the  sigmoid  notch,  the 
coronoid  process,  and  the  condyle. 

The  sigmoid  notch  communicates  with  the  zygomatic  fossa,  and 
transmits  the  masseteric  nerve  and  artery  to  the  deep  surface  of 
the  masseter. 

The  coronoid  process  surmounts  the  anterior  border  of  the  ramus, 


THE  BONES  OF  THE  HEAD  117 

and  is  triangular  and  compressed  from  without  inwards  Its 
external  surface  gives  insertion  to  fibres  of  the  masseter,  and  its 
internal  surface,  as  well  as  the  superior  and  anterior  borders,  to 
part  of  the  temporal  muscle.  The  internal  surface  is  marked  by 
a  ridge  which  extends  downwards  on  the  internal  surface  of  the 
ramus,  not  far  from  the  anterior  border,  to  a  point  on  the  inner  side 
of  the  last  molar  alveolus,  where  it  becomes  continuous  with  the 
mylo-hyoid  ridge.  The  temporal  muscle  continues  to  take  inser- 
tion into  this  ridge,  as  well  as  into  the  elongated  triangular  depres- 
sion between  it  and  the  anterior  border  of  the  ramus. 

The  condyle  surmounts  the  posterior  border  of  the  ramus.  It 
is  oval  and  convex,  and  it  articulates  with  the  anterior  part  of  the 
glenoid  fossa  of  the  temporal,  an  interarticular  fibro  -  cartilage 
intervening.  Its  long  axis  is  oblique,  so  that  the  axes  of  the  two 
condyles,  if  sufficiently  prolonged  inwards  and  slightly  backwards, 
would  meet  near  the  anterior  margin  of  the  foramen  magnum. 
Externally  the  cond^'le  presents  a  projection,  called  the  condylar 
tubercle,  for  the  external  lateral  hgament  of  the  temporo-mandi- 
bular  articulation.  Below  the  condyle  is  the  neck,  which  presents 
anteriorly  a  depression  for  the  insertion  of  the  greater  part  of  the 
external  ptervgoid  muscle. 

The  bone  receives  its  chief  blood-supply  from  the  inferior  dental 
branch  of  the  internal  maxihary  artery.  Other  sources  are  the 
facial,  and  the  sublingual  branch  of  the  lingual. 

Articulations.— With  the  glenoid  fossae  of  the  temporal  bones. 

Structure. — The  inferior  maxilla  is  composed  of  two  dense  plates 
of  compact  bone,  which  are  particularly  strong  in  the  region  of  the 
base,  but  become  thinner  superiorly  at  the  alveolar  border.  Between 
these  plates  there  is  cancellated  tissue  with  wide  meshes. 

Ossification. — The  mandible  is  a  mixed  bone,  being  chiefly  a  membmne- 
bone.  but  in  part  also  a  cartilage  bone.  It  is  ossified  in  connection  with 
Meckel's  cartilage  and  its  fibrous  investment.  Each  half  of  the  bone  has 
one  centre  (Low  and  Fawcett),  which  appears  about  the  sixth  week  of  intra- 
uterine life,   being  only  preceded    by  the   primary  centres  for  the  clavicle. 


Fig.  74. — The  Inferior  Maxillary  Bone  at  Birth. 

It  is  deposited  in  the  membrane  which  covers  the  outer  surface  of  Meckel's 
cartilage  in  the  region  of  the  future  mental  foramen.  From  this  centre  one- 
half  of  the  bone  is  ossified,  chiefly  in  membrane,  but  also  in  cartilage,  namely, 
the  mesial  end  of  Meckel's  cartilage,  and  certain  other  accessory  cartilages. 
The  original  centre  gives  membranous  origin  to  ( i )  the  walls  of  the  alveoli  and 


II{ 


A  MANUAL  OF  ANATOMY 


dental  canal,  (2)  the  basilar  border  and  angle,  and  (3)  the  ramus  as  high  as 
the  inferior  dental  foramen.  The  mesial  part  of  Meckel's  cartilage  is  invaded 
by  osseous  extension  from  the  primordial  membrane-bone  formed  from  the 
single  centre,  the  mesial  part  of  Meckel's  cartilage  becoming  incorporated 
with  the  bone  so  formed,  and  constituting  the  incisor  portion  of  the  mandible. 


AT  BIRTH 


Fig.  75. 


-The  Inferior  Maxillary  Bone  at  different  Periods 
OF  Life. 


The  accessory  cartilages,  which  are  distinct  from  Meckel's  cartilage,  are  as 
follows:  (i)  Condylar,  (2)  coronoid,  and  (3)  symphysial.  All  these  accessory 
cartilages  become  surrounded  and  invaded  by  osseous  extension  from  the 
primordial  membrane-bone  formed  from  the  single  centre,  and  they  become 
incorporated  with  the  parts  of  the  mandible  so  formed. 

The  condylar  cartilage  gives  rise  to  (i)  the  condyle,  and  (2)  the  posterior 


THE  BONES  OF  THE  HEAD 


119 


part  of  the  ramus  as  low  as  the  inferior  dental  foramen.  The  coronoid  cartilage 
gives  rise  to  (i)  the  coronoid  process.,  and  (2)  the  anteriox  part  of  the  ramus 
as  low  as  the  inferior  dental  foramen.  The  symphysial  cartilage  gives  rise  to 
the  limited  symphysial  part  of  the  mandible. 

At  birth  the  mandible  consists  of  two  halves,  connected  at  the  symphysis  by 
fibrous  tissue.  In  the  course  of  the  yi^s^  year  osseous  union  takes  place,  which 
is  completed  towards  the  end  of  the  first  year  or  beginning  of  the  second  year. 

Meckel's  cartilage  extends  on  either  side  downwards  and  forwards  from  the 
periotic  cartilaginous  capsule  to  the  median  line,  where  it  meets  its  fellow. 
It  is  surrounded  by  a  fibrous  investment.  The  proximal  end  of  the  cartilage 
gives  rise  to  the  malleus  and  incus,  two  of  the  three  ossicles  of  the  tympanum. 
The  part  of  the  cartilage  between  the  periotic  cartilaginous  capsule  and 
the  inferior  dental  foramen  disappears,  and  the  membranous  investment  of 
this  part  persists  as  the  spheno-mandibular  ligament.  The  part  of  the  cartilage 
between  the  inferior  dental  foramen  and  the  mental  foramen  also  disappears, 
and  its  membranous  investment  undergoes  ossification  from  a  single  centre, 
and  gives  rise  to  (i)  the  greater  part  of  one-half  of  the  bod>  of  the  mandible 
(incisor  and  symphysial  parts  excepted),  and  (2)  the  lower  half  of  the  ramus 
as  high  as  the  inferior  dental  foramen.  The  mesial  part  of  Meckel's  cartilage, 
when  ossified,  becomes  the  incisor  part  of  the  mandible. 

At  birth  the  inferior  border  is  but  little  developed,  and  the  body  is 
consequently  shallow.  The  rami  are  very  short,  so  that  each  condyle  is 
nearly  on  a  level  with  the  upper  border  of  the  symphysis,  and  the  coronoid 
process  is  rather  longer  than  the  condyle.  The  mental  foramen  is  nearer  the 
inferior  than  the  superior  border,  and  the  angle  amounts  to  1 50 degrees  or  more. 
Subsequently  the  body  increases  in  depth,  the  rami  lengthen,  the  angle  decreases, 
and  the  mental  foramen  gradually  assumes  a  position  midway  between  the 
superior  and  inferior  borders.  In  old  age,  after  the  bone  becomes  edentulous, 
the  alveolar  border  undergoes  absorption,  the  body  consequently  becomes 
shallower,  the  mental  foramen  lies  near  the  superior  border,  the  rami  droop 
backwards,  and  each  angle  becomes  increased  to  about  140  degrees.  For  the 
development  of  the  alveolar  border,  and  its  relation  to  the  milk-teeth,  see  the 
superior  maxilla. 

The  Hyoid  Bone. 

The  hyoid  bone  is  situated  in  the  median  line  of    the  neck, 
between    the    chin    and    the    thyroid    cartilage    of     the    larynx, 
with  which  latter  it  is  connected 
by    means    of    the    thyro-hyoid 
membrane  and  thyro-hyoid  liga- 
ments.    It   is   closely   connected 
with  the  base  of  the  tongue,  and 
is  hence  known  as  the  o.s  linguce. 
In  its  development  it  is  associated 
with   the   skull,    and    it    is   sus- 
pended from  the  lower  ends  of 
the  styloid  processes  of  the  tem- 
poral bones  by  two  fibrous  bands,  Great  Comu 
called  the  stylo-hyoid  ligaments        g^^„  ^^^^^ ' 


(epi-hyals).  It  consists  of  a  central 
portion  or  body  and  two  pairs  of 
cornua,  great  and  small. 

The  body  is  elongated   trans- 
versely, compressed  from  before 
backwards,  and  quadrilateral.     Its  surfaces,  which  are  anterior  and 
posterior,  occupy  an  obH(iue  plane,  being  sloped  downwards  and  for 


Body  and  Hyoid  Tubercle       Superior  Border 

Fig.  76. — The  Hyoid  Bone 
(Anterior  View). 


A  MANUAL  OF  ANATOMY 


wards.  The  anterior  surface  is  convex,  and  is  crossed  transversely 
by  a  ridge,  which  divides  it  into  an  upper  and  a  lower  part.  At 
the  middle  line  this  is  intersected  at  right  angles  by  a  vertical 
ridge,  which,  however,  is  often  incomplete,  being  sometimes  con- 
fined to  the  upper  half,  and  sometimes  to  the  lower.  At  the  place 
of  intersection  of  the  two  ridges  there  is  a  slight  projection,  called 
the  hyoid  tubercle.  Each  half  of  the  anterior  surface  is  thus  mapped 
out  into  an  upper  and  a  lower  irregular  muscular  division.  The 
upper  division,  provided  the  uppn-  border  is  not  very  thick,  gives 
attachment  to  the  genio-hyoid  and  genio-hyo-glossus,  and  the 
lower  division  to  the  digastric,  stylo-hyoid,  and  mylo-hyoid.  The 
posterior  sitrface  i?  concave,  and  is  covered  by  the  thyro-hyoid 
membrane  as  it  ascends  to  be  attached  to  the  superior  border,  a 
synovial  bursa  intervening.    This  surface  is  related  to  the  epiglottis. 


Great  Cirnu    


Small  Cornu 


Middle 

Constrictor 

^Hyo-glossus 


•  -Chondro-glossus 


enio-hyo-glossus 
"Digastric 
Stylo-hyoid 


"Omo-hyoid  (Ant.  Bellj') 


Fig. 


Thyro-hyoid 
,,  Mylo-hyoid 

Stemo-hyoid 
Genio-hyoid 

-The  Hyoid  Bone,  showing  its  Muscular  Attachments. 


The  superior  border  is  somewhat  thick,  and  occasionally  is  really  a 
surface,  in  which  cases  it  gives  attachment  to  the  genio-hyo- 
glossus,  whilst  its  posterior  lip  gives  attachment  to  the  thyro-hyoid 
membrane.  The  inferior  border  is  sharp,  and  gives  insertion  to  the 
sterno-hyoid,  anterior  belly  of  the  omo-hyoid,  and  thjnro-hyoid 
muscles.     Each  lateral  border  is  connected  with  a  great  cornu. 

The  great  cornua  project  upwards  and  backwards  from  the  lateral 
borders  of  the  body.  Each  is  compressed  from  above  downwards, 
and  gradually  diminishes  in  size  to  its  termination,  where  it  ends 
in  a  small  tubercle  for  the  attachment  of  the  thyro-hyoid  ligament. 
It  gives  attachment  to  fibres  of  the  th^TO-hyoid,  hyo-glossus,  middle 
constrictor  muscle  of  the  pharynx,  and  the  thyro-hyoid  membrane. 
Each  great  cornu  is  connected  with  the  body  b}^  synchondrosis 
up  to  middle  life,  after  which  ankylosis  usually  takes  place. 


THE  BONES  OF  THE  HEAD  121 

The  small  cornua  are  short  conical  nodules,  each  of  which 
projects  upwards  and  backwards  from  the  junction  between  the 
body  and  great  cornu.  Its  tip  gives  attachment  to  the  stylo- 
hyoid ligament,  which  is  sometimes  ossified,  a  possible  condition 
to  be  borne  in  mind  during  digital  examination  of  the  upper  part 
of  the  pharynx.  Elsewhere  it  gives  attachment  to  the  middle 
constrictor  muscle  of  the  pharynx,  and  sometimes  to  the  chondro- 
glossus.  The  small  cornua  may  be  wholly  or  partially  cartilaginous, 
and  they  articulate  with  the  body  by  a  synovial  joint,  unless  in 
advanced  life,  when  ankylosis  usually  takes  place. 

Ossification. — The  hyoid  bone  is  developed  in  connection  with  the  second 
and  third  visceral  arches.  The  cartilaginous  bar  of  the  second  visceral  arch 
is  known  as  the  hyoid  bar,  and  is  continuous  with  its  fellow  at  the  median  line. 
The  cartilaginous  bar  of  the  third  visceral  arch  is  known  as  the  thyro-hyoid 
bar,  and  at  the  median  line  it  blends  with  the  junction  of  the  hyoid  bars. 
With  the  foregoing  proviso,  the  hyoid  bone  is  developed  from  five,  or,  it  may 
be,  six  centres.  One,  or,  it  may  be,  two  are  deposited  during  the  last  month 
of  intra-u ferine  life  at  the  place  of  fusion  of  the  two  hyoid  bars.  If  there  are 
two  centres  they  soon  jojn,  and  give  rise  to  the  greater  part  of  the  body  of  the 
hyoid  bone  or  basi-hyal.  About  the  same  time  a  centre  appears  at  eitlier  side 
in  the  thyro-hyoid  bar  of  the  third  visceral  arch,  and  from  these  centres  are 
developed  the  great  cornua  or  thyro-hyals,  and  the  adjacent  portions  of  the 
body.  In  the  course  of  the  fi.rst  year  the  two  remaining  centres  appear,  one  at 
either  side,  in  the  lower  or  mesial  part  of  each  hyoid  bar,  and  these  centres 
give  rise  to  the  small  cornua  or  cerato-hyals.  The  great  cornua  join  the 
body  in  middle  life,  but  the  small  cornua  do  not  join  until  advanced  life. 
The  stylo-hyoid  ligaments  may  become  ossified  more  or  less  completely,  and 
so  represent  the  epi-hyal  bones  of  many  animals. 

The  Skull  as  a  Whole. 

The  skull  is  spheroidal,  the  superior  surface  being  convex,  the 
lateral  surfaces  compressed,  and  the  inferior  surface  flat  and 
very  irregular.  It  presents  for  consideration  six  regions — superior, 
inferior,  anterior,  posterior,  and  two  lateral. 

I.  The  Posterior  Region. 

The  posterior  region  (norma  occipitalis)  is  formed  by  the  posterior 
parts  of  the  jjarietal  bones  and  the  upper  or  interparietal  division 
of  the  tabular  part  of  the  occipital.  It  is  limited  above  by  a  line 
connecting  the  j)arietal  eminences,  and  below  by  the  superior 
curved  lines  of  the  occii)ital,  whilst  laterally  it  is  limited  by  a 
line  connecting  the  i)arietal  eminence  with  the  lateral  angle  of  the 
tabular  jjart  of  the  occipital.  A  little  above  the  centre  it  presents 
the  lambda,  which  is  the  place  where  the  sagittal  meets  the  lambdoid 
suture  in  the  situation  of  the  posterior  fontanelle  of  early  life. 
Radiating  from  the  lambda  there  arc  three  sutures.  One  passes 
uj)wards  and  forms  the  posterior  part  of  the  sagittal  or  interj)arietal 
suture.  The  other  two,  diverging,  pass  outwards  and  downwards, 
and  form  together  the  laml)doid  or  occipito-parietal  suture.  About 
I  inch  above  the  lambda,  at  either  side  of  the  sagittal  suture,  is  the 


122  A  MANUAL  OF  ANATOMY 

parietal  foramen,  and  the  point  where  the  horizontal  Une  connecting 
the  parietal  foramina  intersects  the  sagittal  suture  is  known  as  the 
obelion,  which  coincides  with  the  situation  of  the  sagittal  fontanelle 
of  early  foetal  life.  This  part  of  the  sagittal  suture  is  less  serrated 
than  elsewhere,  and  is  the  first  to  show  signs  of  obliteration.  At 
the  lower  part  of  the  posterior  region  in  the  middle  line  is  the 
external  occipital  protuberance,  which  is  known  as  the  inion.  A 
little  above  this  is  the  occipital  point,  which  is  the  part  in  the 
median  plane  at  the  greatest  distance  from  the  glabella  of  the 
frontal.  The  tabular  part  of  the  occipital  may  present  an  occipital 
suture,  if  the  interparietal  division  persists  as  a  separate  bone. 

2.  The  Superior  Region. 

The  superior  region  (norma  verticalis)  varies  in  shape.  It  may 
be  oval  with  its  long  axis  antero-posterior,  and  broader  behind  than 
in  front.  Such  skulls  are  called  dolicocephalic,  and  in  them  the 
zygomatic  arches  are  usually  visible  at  either  side  from  above,  a 
condition  known  as  phenozygous.  In  other  cases  the  superior 
region  assumes  a  circular  shape,  due  to  the  broadening  of  its 
anterior  part.  Such  skulls  are  called  brachy cephalic,  and  in  them 
the  zygomatic  arches  are  usually  concealed  from  above,  a 
condition  known  as  cryptozygous.  Some  skulls  are  intermediate 
between  the  dolicocephalic  and  brachycephalic,  and  are  known 
as  mesaticocephalic.  The  bones  which  enter  into  the  superior 
region  are  the  upper  part  of  the  frontal  and  the  anterior  parts 
of  the  parietals.  It  is  limited  in  front  by  a  line  connecting 
the  frontal  eminences,  behind  by  a  line  connecting  the  parietal 
eminences,  and  on  either  side  by  the  superior  temporal  ridges  of 
the  parietal  and  frontal  bones.  The  highest  point  is  situated  in 
the  course  of  the  sagittal  suture,  and  is  called  the  vertex.  The 
sutures  in  this  region  are  usually  two  in  number,  coronal  and 
sagittal,  but  there  is  sometimes  a  third,  namely,  the  metopic  or 
frontal.  The  coronal  or  fronto-parietal  suture  lies  between  the 
frontal  and  parietal  bones.  The  anterior  part  of  the  sagittal  or 
interparietal  suture  meets  the  coronal  suture  from  behind,  and  the 
place  of  junction  is  known  as  the  bregma,  which  coincides  with 
the  anterior  fontanelle  of  early  life.  If  there  is  a  metopic  or 
frontal  suture  present  it  connects  the  two  halves  of  the  frontal 
bone,  and  is  a  continuation  of  the  sagittal  suture  as  far  as  the 
fronto-nasal  suture.  The  superior  region,  as  viewed  from  above, 
reveals  certain  parts  of  the  posterior  region,  namely,  the  posterior 
portions  of  the  parietals,  with  the  parietal  foramina  and  obelion,  the 
lambda,  the  interparietal  portion  of  the  occipital,  and  the  lambdoid 
suture. 

3.  The  Anterior  Region. 

The  anterior  region  (norma  frontalis  et  facialis)  is  limited  above 
by  a  line  connecting  the  frontal  eminences,  and  below  by  the  lower 


THE  BONES  OF  THE  HEAD  123 

border  of  the  inferior  maxilla.  It  is  formed  by  a  portion  of  the 
frontal,  the  nasals,  superior  maxillae,  malars,  and  inferior  maxilla. 
It  is  subdivided  into  two  portions,  frontal  and  facial. 

The  frontal  division  is  limited  laterally  by  the  superior  temporal 
ridge,  below  by  the  supra-orbital  border  at  either  side  of  the 
'  median  line,  and  by  the  fron to-nasal  and  fronto-maxillary  sutures 
close  to  the  median  line.  It  presents  the  frontal  eminences, 
superciliary  ridges,  external  and  internal  angular  processes,  supra- 
orbital notches,  or  it  may  be  foramina,  all  on  either  side  of  the 
median  line,  and  the  nasal  eminence  or  glabella  at  the  median  line, 
between  the  two  superciliary  ridges.  The  most  prominent  point  of 
the  glabella  is  known  as  the  antinion.  The  meeting  of  the  two 
fronto-nasal  sutures  is  known  as  the  nasion  or  nasal  point.  The 
centre  of  a  line  drawn  from  one  temporal  ridge  to  the  other  across 
the  narrowest  part  of  the  frontal  region  is  known  as  the  ophryon. 

The  upper  part  of  the  facial  division  presents  the  openings  of  the 
orbits.  These  cavities  are  separated  at  the  median  line  by  the 
bridge  of  the  nose,  which  is  formed  by  the  na~al  bones  and  the 
nasal  processes  of  the  superior  maxillae,  whilst  externally  each  orbit 
is  limited  by  the  malar  bone  and  the  external  angular  process  of 
the  frontal.  The  point  at  the  inner  angle  of  the  orbit  where  the 
horizontal  fronto-maxillary  suture  meets  the  vertical  lachrymo- 
maxillary  suture  is  known  as  the  dacryon,  and  the  lower  part  of 
the  internasal  suture  is  known  as  the  rhinion.  Below  the  nasal 
bones  is  the  anterior  nasal  aperture.  It  is  bounded  on  either  side 
by  the  nasal  notch  on  the  mesial  border  of  the  superior  maxilla, 
and  above  by  the  inferior  borders  of  the  nasal  bones,  whilst 
interiorly  in  the  median  line  is  the  anterior  nasal  spine  in  two 
halves.  The  central  point  of  the  base  of  this  spine  is  known  as 
the  subnasal  point.  The  anterior  nasal  aperture  is  the  common 
external  opening  of  the  two  nasal  fossae,  which  are  separated 
by  a  septum  composed  of  bones  and  cartilage.  An  inspection  of 
each  nasal  fossa  will  reveal  two  bulging  prominences  on  its  outer 
wall,  the  lower  of  which  is  formed  by  the  inferior  turbinate 
bone,  and  the  upper  by  the  inferior  turbinate  process  of 
the  ethmoid.  Below  the  former  is  the  inferior  meatus,  whilst 
between  the  two  is  the  middle  meatus.  The  outer  wall,  from  its 
irregularity,  thus  presents  a  marked  contrast  to  the  floor,  which  is 
smooth  and  unbroken.  The  osseous  septum  is,  as  a  rule,  deflected 
to  one  side,  most  commonly  the  left,  thus  diminishing  the  capacity 
of  the  left  fossa.  Below  the  anterior  nasal  aperture  are  the  alveolar 
borders  of  the  superior  maxilla;,  which  lodge  the  upper  teeth.  The 
point  where  the  anterior  margins  of  these  two  borders  meet  in  the 
median  line  is  known  as  the  alveolar  point.  Below  these  borders 
is  the  entrance  to  the  buccal  cavity,  and  below  this  is  the  alveolar 
border  of  the  inferior  maxilla,  which  lodges  the  lower  teeth.  The 
middle  j)oint  of  the  anterior  lij)  of  the  lower  border  of  the  inferior 
maxiJla  is  known  as  the  mental  point  or  gnathion. 

The    sujjerior  maxilla;   liaving   a   wider   lange  than  the   inferior 


124  A  MANUAL  OF  ANATOMY 

maxilla,  the  upper  teeth  slightly  overlap  the  lower.  According  to 
the  degree  of  projection  of  the  maxillary  bones,  skulls  are  spoken 
of  as  orthognathous,  prognathous,  or  mesognathous. 

The  chief  small  foramina  of  the  anterior  region  are  as  follows, 
from  above  downwards  at  either  side  :  supra- orbital,  at  the  junction 
of  the  outer  two-thirds  and  inner  third  of  the  supra-orbital  arch 
of  the  frontal  (which  in  most  cases  is  a  notch)  ;  infra-orbital,  in  the 
superior  maxilla  near  the  infra- orbital  margin  ;  mental,  in  the 
inferior  maxilla  in  line  with  the  septum  between  the  bicuspid 
alveoli ;  and  malar,  situated  above  the  malar  tuberosity.  The 
supra-orbital,  infra-orbital,  and  mental  foramina  are  in  the  same 
perpendicular  line,  and  transmit  the  following  important  sensory 
nerves,  in  order  from  above  downwards  :  supra- orbital,  infra- 
orbital, and  mental,  which  are  branches  of  the  ophthalmic, 
superior  maxillary,  and  inferior  maxillary  divisions  of  the  Gasserian 
ganglion  on  the  sensory  root  of  the  fifth  cranial  nerve.  The  malar 
foramen  transmits  the  malar  branch  of  the  temporo-malar  or 
orbital  nerve,  from  the  superior  maxillary  division  of  the  fifth. 

The  sutures  in  the  anterior  region  are  as  follows  :  fronto-malar, 
fronto-maxillary,  lachrymo-maxillary,  fronto-nasal,  internasal,  naso- 
maxillary, malo-maxillary,  and  intermaxillary. 

The  Orbits. — The  orbits  have  the  shape  of  four-sided  pyramids, 
their  bases  being  directed  forwards  and  outwards,  and  their  apices 
backwards  and  inwards.  The  inner  walls  are  nearly  parallel,  and 
occupy  an  antero-posterior  plane,  but  the  outer  walls  diverge,  the 
plane  of  each  being  directed  forwards  and  outwards,  so  that  they 
almost  form  a  right  angle  with  each  other.  Each  orbit  is  lined 
with  periosteum,  which  is  continuous  with  the  dura  mater  through 
the  sphenoidal  fissure,  and  it  contains  the  eyeball,  with  the  ocular 
muscles,  nerves,  and  bloodvessels,  the  lachrymal  gland,  and  a  large 
amount  of  fat.  It  presents  an  apex,  a  base,  and  four  sides  or 
walls.  The  apex,  which  is  directed  backwards  and  inwards,  is 
formed  by  the  inner  end  of  the  sphenoidal  fissure,  and  just  above 
and  internal  to  this  is  the  optic  foramen.  The  base  is  free,  and 
is  directed  forwards  and  outwards.  Its  circumference  presents  the 
fronto-malar  suture  externally,  the  malo-maxillary  interiorly,  and 
the  fronto-maxillary  internally.  The  walls  are  superior,  inferior, 
external,  and  internal. 

The  superior  wall  or  roof,  which  is  thin  and  brittle,  is  formed 
mainly  by  the  orbital  plate  of  the  frontal,  and  behind  this  by  the 
small  wing  of  the  sphenoid.  It  is  smooth  and  concave.  Within 
the  external  angular  process  it  presents  the  lachrymal  fossa  for 
the  lachrymal  gland,  and  near  the  internal  angular  process  the 
trochlear  fossa,  which  gives  attachment  to  the  cartilaginous  pulley 
of  the  superior  oblique  muscle  of  the  eyeball. 

The  inferior  wall  or  floor  is  foimed  by  three  bones,  namely,  the 
orbital  surface  (orbital  plate)  of  the  superior  maxilla,  external  to 
which  is  a  part  of  the  orbital  process  of  the  malar,  whilst  posteriorly 
is  the  orbital  process  of  the  palate  bone.    The  floor  is  thin,  and  sepa- 


THE  BONES  OF  THE  HEAD 


125 


Anterior  Ethmoidal  Canal 
Posterior  Ethmoidal  Canal , 
Supra-orbital  Notch 


Optic  Foramen 
Sphenoidal  Fissure 


Malar  Foramen   _ 
Infra-orb.  Foramen 


Subnasal  Point 


Mental  Foramen  / 


Symphys 
\  Mental  Protuberance 


Gnathion 

Fig.   78. — The   Anterior  Region   of  the   Skull   (Norma   Frontalis   et 

Facialis). 

I,  Nasal.  II,  Nas.  Proc.  of  Sup.  Maxilla.  Ill,  Lachrymal.  IV,  Ethmoid 
(Os  Planum).  V,  Orbital  Proc.  of  Malar.  VI,  Orb.  Surf,  of  Great  Wing  of 
Sjjhenoid.  VII,  Orb.  I^lato  of  I-rontal.  VIII,  Orb.  Surf,  of  Sup.  Maxilla. 
IX,  Frontal.  IX',  Tc-ni]).  Div.  of  I'^ontal.  X,  Parietal.  XI,  Great  Wing 
of  Si)henoid.  XII,  Scpuim.  Port,  of  Tem]xjral.  XIII,  Malar.  XIV,  Inf. 
Maxilla.      XV,  Temporal  Fossa. 


126  A  MANUAL  OF  ANATOMY 

rates  the  orbit  from  the  subjacent  antrum  of  Highmore.  It  is 
traversed  from  behind  forwards  by  the  infra-orbital  canal,  which 
posteriorly  is  a  groove.  At  its  anterior  and  inner  part  is  the 
upper  orifice  of  the  lachrymal  canal,  and  external  to  this  is  a  small 
depression  which  gives  origin  to  the  inferior  oblique  muscle  of  the 
eyeball. 

The  outer  wall  looks  forwards  and  inwards,  and  is  formed 
mainly  by  the  orbital  surface  of  the  great  wing  of  the  sphenoid, 
and  in  front  of  this  by  a  part  of  the  orbital  process  of  the 
malar.  Between  the  outer  wall  and  the  floor  is  the  spheno-maxillary 
fissure,  the  front  part  of  which  communicates  with  the  zygomatic 
fossa,  and  the  back  part  with  the  spheno-maxiUary  fossa.  Between 
the  outer  wall  and  the  roof,  towards  the  posterior  part  is  the  outer 
portion  of  the  sphenoidal  fissure.  The  part  of  the  orbital  process  of 
the  malar  which  forms  the  front  part  of  this  wall  presents  two 
foramina  (sometimes  one)  leading  to  the  malar  and  temporal  canals. 

The  inner  wall  is  almost  vertical,  and  looks  directly  outwards. 
It  is  formed  by  four  (sometimes  five)  bones,  in  the  following  order 
from  before  backwards  :  (i)  the  nasal  process  of  the  superior 
maxilla  ;  (2)  the  lachrymal ;  (3)  the  os  planum  or  orbital  plate  of 
the  ethmoid  ;  and  (4)  the  anterior  part  of  the  lateral  surface  of  the 
body  of  the  sphenoid.  If  there  are  five  bones,  the  fifth  is  a  portion 
of  the  sphenoidal  spongy  bone,  which  would  lie  behind  the  os 
planum  of  the  ethmoid.  Between  the  inner  wall  and  roof,  in  the 
ethmo-frontal  suture,  are  the  openings  of  the  anterior  and  posterior 
ethmoidal  or  internal  orbital  canals.  At  the  anterior  part  of  this 
wall  is  the  lachrymal  groove,  which  lodges  the  lachrymal  sac,  and 
behind  this  is  the  lachrymal  crest,  which  gives  origin  to  the  tensor 
tarsi  muscle. 

The  orbital  sutures  are  as  follows :  superiorly,  the  orbito- 
sphenoidal ;  interiorly,  the  malo-maxillary  and  palato-maxillary ; 
externally,  the  spheno-malar ;  and  internally,  from  before  backwards, 
the  lachrymo-maxillary,  ethmo-lachrymal,  and  ethmo-sphenoidal, 
all  of  which  three  are  disposed  vertically,  and  ethmo-frontal,  which 
is  antero-posterior. 

The  orbit  has  ten  (sometimes  nine)  openings  communicating  with 
it.  (i)  The  sphenoidal  fissure  or  foramen  lacerum  anterius  or 
orbitale,  the  wide  inner  end  of  which  forms  the  apex  of  the  cavity, 
whilst  the  narrow  outer  part  lies  between  the  roof  and  the  outer 
wall.  This  fissure  transmits  (a)  the  third  nerve,  the  sympa- 
thetic filament  to  the  lenticular  ganglion,  the  fourth,  the  three 
branches  (frontal,  lachrymal,  and  nasal)  of  the  ophthalmic  division 
of  the  fifth,  and  the  sixth,  cranial  nerves  ;  (b)  the  superior  and  in- 
ferior ophthalmic  veins ;  (c)  the  orbital  branch  of  the  middle 
meningeal  artery  ;  and  {d)  a  portion  of  the  dura  mater.  (2)  The 
optic  foramen,  situated  above  and  internal  to  the  apex,  for  the  optic 
nerve  and  the  ophthalmic  artery,  along  with  a  plexus  of  sympa- 
thetic nerve  fibres.  (3)  The  supra-orbital  notch  (or  it  may  be 
foramen),  on  the  supra-orbital  border,  for  the  supra-orbital  nerve 


THE  BONES  OF  THE  HEAD  127 

and  vessels.  (  4)  The  opening  of  the  infra-orbital  canal,  on  the 
floor,  transmitting  the  infra-orbital  nerve  and  vessels.  (5)  The 
opening  of  the  temporal  canal,  and  (6)  the  opening  of  the 
malar  canal,  both  on  the  outer  wall,  for  the  branches  of  the 
temporo-malar  or  orbital  nerve  from  the  superior  maxillary  division 
of  the  fifth  cranial  nerve.  (The  temporal  and  malar  openings 
may  be  combined  into  one.)  (7)  The  spheno-maxillary  fissure, 
at  "the  junction  of  the  outer  wall  and  floor,  which  transmits  the 
superior  maxillary  nerve  to  become  the  infra-orbital,  and  the  infra- 
orbital vessels.  (8)  The  lachrymal  canal,  at  the  anterior  part  of  the 
inner  wall,  for  the  nasal  duct.  (9)  The  anterior  ethmoidal  canal, 
and  (10)  the  posterior  ethmoidal  canal,  both  situated  on  the  inner 
wall,  the  former  transmitting  the  nasal  nerve  and  anterior  ethmoidal 
vessels,  and  the  latter  the  posterior  ethmoidal  vessels  and  the 
spheno-ethmoidal  nerve. 

Eight  muscles  take  their  origin  within  each  orbit.  The  four  recti 
arise  from  a  fibrous  ring  surrounding  the  optic  foram.en.  The 
levator  palpebrse  superioris  arises  above  and  in  front  of  the  optic 
foramen,  and  the  superior  oblique  arises  internal  to  the  last  named. 
The  inferior  oblique  arises  from  the  depression  at  the  anterior  and 
inner  part  of  the  floor,  external  to  the  orifice  of  the  lachrymal 
canal,  and  the  tensor  tarsi  arises  from  the  lachrymal  crest  behind  the 
lachrymal  groove. 

The  Nasal  Fossae. — The  nasal  fossae  are  two  in  number,  right  and 
left,  and  they  lie  on  either  side  of  the  median  plane.  They  extend 
horizontally  from  before  backwards,  opening  on  the  face  as  the 
anterior  nares  by  means  of  the  anterior  nasal  aperture,  and  com- 
municating posteriorly  with  the  naso-pharynx  by  the  posterior 
nares.  The  vertical  and  antero-posterior  dimensions  of  each  fossa 
greatly  exceed  the  transverse.  The  two  fossae  are  separated  from 
each  other  by  a  partition,  called  the  septum  nasi,  which  is  partly 
osseous  and  (in  the  recent  state)  partly  cartilaginous.  Each  fossa 
presents  a  roof,  floor,  and  two  walls,  inner  and  outer. 

The  roof  over  its  central  part  is  horizontal,  but  in  front  and  behind 
it  is  inclined  downwards.  Six  bones  enter  into  its  formation.  The 
central  portion  is  formed  by  one-half  of  the  cribriform  plate  of  the 
ethmoid.  The  sloping  anterior  part  is  formed  by  the  grooved  ala  of 
the  frontal  bone,  by  the  side  of  the  nasal  spine,  and  the  posterior 
surface  of  the  nasal  bone.  The  sloping  posterior  part  is  formed  by 
portions  of  the  anterior  and  inferior  surfaces  of  the  body  of  the 
sphenoid,  the  ala  of  the  vomer,  and  a  part  of  the  sphenoidal  pro- 
cess of  the  palate  bone.  The  central  part  of  the  roof  is  perforated 
by  the  foramina  of  one-half  of  the  cribriform  plate,  including  the 
nasal  slit,  and,  at  its  back  part,  the  aperture  of  the  sphenoidal  air 
sinus  opens  into  the  spheno-ethmoidal  recess. 

The  floor  is  smooth  and  concave  from  side  to  side.  Over  its 
anterior  three-fourths  it  is  formed  by  the  ])a]atal  process  of  the 
superior  maxilla,  and  over  its  posterior  fourth  by  the  horizontal 
plate  of  the  jjalate  bone.     Near  its  anterior  extremity,  close  to 


128 


A   MANUAL  OF  ANATOMY 


the  incisor  crest  of  the  superior  maxilla,  is  the  upper  opening  of 
Stensen's  canal. 

The  inner  wall  is  known  as  the  septum  nasi.  The  osseous 
septum  is  formed  by  ten  bones,  in  the  following  order,  as  nearly  as 
possible,  from  below  upwards  :  the  nasal  crests  of  the  palatal 
processes  of  the  superior  maxillae  and  palate  bones  ;  the  vomer  ; 
the    perpendicular    plate  j,  of    the    ethmoid ;  the   rostrum    of    the 

Frontal  Sinus 

Crista  Galli 
\ 
\ 

Half  of  Cribriform  Plate  . 

Perpend.  Plate  of  Ethmoid 
(showing  Olfact.  Grooves) 


Sphenoidal  Sinu 
Sella  Turcica 

Dorsum  Selte    i 


Clivus 


Nasal  Spine  of 
y   Frontal 

Nasal  Bone 


Atrium  of 
Middle  Meatus 


Ext.  Pteryg.  Plate 


Hamular  Process  of  ■^ 
Int.  Pterygoid  Plate 


Vomer 


Upper  Opening  of 
Stensen's  Canal 


Foramen  of  Stensen 

Fig.  79. — Sagittal  Section  of  the  Anterior  Part  of  the  Skull 
TO  THE  Right  of  the  Nasal  Septum. 


sphenoid ;  the  nasal  crest  of  the  nasal  bones ;  and  the  nasal 
spine  of  the  frontal.  The  anterior  border  of  the  osseous  septum 
presents  a  triangular  deficiency,  which  is  occupied  in  the  recent 
state  by  the  septal  cartilage.  The  posterior  border  is  formed  by 
the  posterior  border  of  the  vomer,  which  lies  between  the  posterior 
nares.  As  previously  stated,  the  septum  is  usually  deflected  to  one 
side,  most  commonly  the  left. 


THE  BONES  OF  THE  HEAD  129 

The  outer  wall  is  characterized  by  great  irregularity,  and  is 
formed  by  seven  bones,  in  the  following  order,  as  nearly  as  possible, 
from  before  backwards  :  (i)  the  nasal  ;  {2)  the  nasal  process  of 
the  superior  maxilla  ;  (3)  the  lachrymal  ;  (4)  the  internal  surface 
of  the  lateral  mass  of  the  ethmoid,  presenting  the  superior  and 
inferior  turbinate  processes  (superior  and  middle  spongy  bones)  ; 
(5)  the  inferior  turbinate  or  spongy  bone  which  lies  below  the  last 
named  ;  (6)  the  perpendicular  plate  of  the  palate  bone,  together 
with  })arts  of  its  orbital  and  sphenoidal  processes  ;  and  (7)  the 
internal  pterygoid  plate  of  the  j)terygoid  jjrocess  of  the  sphenoid. 

The  bulging  projections  on  this  wall  are  produced  by  the  superior 
and  inferior  turbinate  processes  of  the  ethmoid  and  the  inferior 
turbinate  bone,  in  this  order  from  above  downwards,  and  the  deep 
channels  thereby  formed  are  known  as  the  meatus.  These  are 
three  in  number — superior,  middle,  and  inferior.  The  superior 
meatus  is  situated  towards  the  back  part  of  the  outer  wall,  where 
it  lies  between  the  superior  and  inferior  turbinate  processes  of  the 
ethmoid.  It  is  comparatively  short,  and  is  directed  obliquely 
forwards  and  upwards.  The  posterior  ethmoidal  cells  open  into 
it  anteriorly,  and  the  spheno-palatine  foramen  posteriorly.  The 
middle  meatus,  which  is  longer  than  the  superior,  lies  between  the 
inferior  turbinate  process  of  the  ethmoid  and  the  inferior  turbinate 
bone.  At  its  anterior  part  it  turns  upwards,  and  is  continued  into 
the  passage  known  as  the  infundibulum,  which  communicates  with 
the  frontal  air  sinus  of  its  own  side.  The  ascending  part  also 
communicates  with  the  anterior  ethmoidal  cells.  The  middle 
portion  communicates  with  the  middle  ethmoidal  cells,  and  pre- 
sents the  opening  of  the  antrum  of  Highmore.  The  inferior  meatus, 
which  is  the  longest  of  the  three,  lies  between  the  inferior  turbinate 
bone  and  the  floor  of  the  nasal  fossa.  Near  its  anterior  part 
is  the  lower  orifice  of  the  lachrymal  canal,  which  lodges  the  nasal 
duct. 

The  Air  Sinuses. — These  are  hollow  cavities  lined  with  mucous 
membrane,  which  are  contained  within  the  following  bones  :  the 
frontal,  sphenoid,  ethmoid,  superior  maxillae,  and  mastoid  portions 
of  the  temporals.  They  communicate  directly  with  the  nasal  fossai, 
except  the  mastoid  cells,  which  at  either  side  are  in  communica- 
tion with  the  tympanum,  that  in  turn  being  connected  by  means  of 
the  Eustachian  tube  with  the  naso-pharynx,  at  a  point  external  to 
the  posterior  naris.  The  maxillary  air  sinus  or  antrum  of  Highmore 
appears  about  the  fourth  month  of  intra-uterine  life,  but  the 
other  air  sinuses  do  not  appear  until  childhood,  and  they  do 
not  show  much  development  until  the  period  of  puberty  (see 
the  individual  bones).  In  f)ld  age  they  all  tend  to  become 
enlarged. 

The  frontal  sinus  (through  means  of  the  infundibulum)  and  the 
anterior  ethmoidal  cells  ojjen  into  the  ascending  front  part  of  the 
middle  meatus.  The  middle  ethmoidal  cells  and  the  maxillary 
sinus  open  into  the  central  portion  of  the  middle  meatus.     The 

9 


I30  A  MANUAL  OF  ANATOMY 

posterior  ethmoidal  cells  open  into  the  superior  meatus,  and  the 
sphenoidal  sinus  opens  into  the  spheno-ethmoidal  recess. 

The  foramina  which  perforate  the  cribriform  plate  of  the  ethmoid 
transmit  the  filaments  of  the  olfactory  bulb,  and  are  arranged  in 
three  sets,  as  follows  :  a  middle  set,  which  are  simple  perforations, 
and  an  external  and  internal  set,  which  lead  into  small  canals. 
These  canals  descend  on  the  inner  surface  of  the  lateral  mass  and 
corresponding  part  of  the  perpendicular  plate  respectively,  branching 
and  opening  out  as  they  descend.  The  nasal  slit  transmits  the 
nasal  nerve  and  anterior  ethmoidal  artery.  The  spheno-palatine 
foramen  leads  from  the  spheno-maxillary  fossa,  and  transmits, 
the  internal  nerves  of  Meckel's  ganglion  and  the  spheno-palatine 
artery. 

The  anterior  nares  are  the  orifices  by  which  the  nasal  fossae 
open  on  the  face  through  means  of  the  anterior  nasal  aperture. 
Each  naris  is  semipyriform,  and  is  bounded  above  by  the  lower 
border  of  the  nasal,  externally  by  the  nasal  notch  of  the  superior 
maxilla,  and  inferiorly  by  the  premaxillary  portion  of  that  bone. 

The  posterior  nares  or  choanae  are  situated  at  the  posterior 
extremities  of  the  nasal  fossae,  between  the  pterygoid  processes 
of  the  sphenoid,  and  they  communicate  in  the  recent  state 
with  the  naso-pharynx.  They  are  oblong  from  above  down- 
wards, and  their  plane  is  oblique,  being  directed  downwards  and 
slightly  forwards.  Each  naris  is  bounded  externally  by  the  internal 
pterygoid  plate  of  the  sphenoid,  internally  by  the  posterior  border 
of  the  vomer,  which  separates  the  two  nares,  inferiorly  by  the 
posterior  border  of  the  horizontal  plate  of  the  palate  bone,  and 
superiorly  by  the  vaginal  process  of  the  sphenoid,  ala  of  the  vomer, 
and  sphenoidal  process  of  the  palate  bone. 

4.  The  Lateral  Region. 

The  lateral  region  (norma  lateralis)  is  formed  by  portions  of  the 
frontal,  parietal,  sphenoid,  temporal,  malar,  superior  maxilla,  and 
inferior  maxilla.  It  is  somewhat  triangular,  with  the  base  directed 
upwards.  The  base  represents,  for  the  most  part,  the  superior  tem- 
poral ridge,  and  corresponds  with  a  curved  line  connecting  the 
external  angular  process  of  the  frontal  with  the  lateral  angle  of  the 
tabular  part  of  the  occipital.  In  front  and  behind  it  is  limited  by 
lines  connecting  the  extremities  of  the  base  with  the  ramus  of  the 
inferior  maxilla  in  the  vicinity  of  the  angle.  This  region  presents 
the  zygomatic  arch,  and,  from  behind  forwards,  are  seen  the  mastoid 
process,  opening  of  the  external  auditory  meatus  and  suprameatal 
triangle,  condyle  of  the  inferior  maxilla,  lying  in  the  anterior  part 
of  the  glenoid  fossa,  eminentia  articularis,  and  the  sigmoid  notch 
and  coronoid  process  of  the  inferior  maxilla,  the  latter  lying  within 
the  front  part  of  the  zygomatic  arch.  The  central  point  of  the 
orifice  of  the  external  auditory  meatus  is  known  as  the  auricular 
point,  and  the  outer  side  of  the  angle  of  the  inferior  maxilla  is 


THE  BONES  OF  THE  HEAD 


131 


Fig.  80. — The  Lateral  Region  of  the  Skull   (Norma  Lateralis). 

I,  I,  Frontal  ;  11,  II,  Parietal  ;  IH,  Occipital  ;  IV,  Great  Wing  of  Sphenoid  ; 
\',  Squamous  Portion  of  Temporal  ;  VL  Mastoid  Portion  of  Temporal  ; 
VIL  Zygoma;  VIH,  Malar;  IX,  Nasal;  X,  Superior  Maxilla  (Nasal 
Process)  ;  XI,  Lachrymal  ;  XII,  Ethmoid  (Os  Planum)  ;  XIII,  Inferior 
Maxilla. 

I,  Bregma;  2,  Superior  Temporal  Ridge;  3,  Inferior  Temporal  Ridge; 
4,  Obelion  ;  5,  Occipital  Point;  6,  Inion  ;  7,  Asterion  ;  8,  Entomion  ; 
9,  Auricular  Point;  10,  Gonion  ;  11,  Mental  Foramen;  12,  Alveolar 
Point;  13,  Subnasal  Point;  14,  Jugal  Point;  15,  Lachrymal  Groove; 
16,  Dacryon  ;  17,  Nasion  ;  18,  Glabella  ;  19,  Ophryon  ;  20,  Pterion  ; 
21,  Ste{)hanion. 


9-2 


132 


A  MANUAL  OF  ANATOMY 


known  as  the  gonion.  The  point,  situated  at  the  angle  which 
the  posterior  border  of  the  frontal  process  of  the  malar  makes  with 
the  superior  border  of  its  zygomatic  process,  is  known  as  the  jugal 
point. 

The  sutures  in  this  region  are  the  fronto-malar,  spheno-malar, 
fronto-sphenoidal,  spheno-parietal,  squamo-sphenoidal,  coronal, 
squamous  or  squamo-parietal,  temporo-malar  (zygomatic),  parieto- 
mastoid, and  a  portion  of  the  occipito-mastoid. 

The  point  where  the  superior  temporal  ridge  crosses  the  coronal 
suture  is  known  as  the  stephanion,  and  the  point  where  the 
parieto-mastoid,  occipito-mastoid,  and  lambdoid  sutures  meet  is 
known  as  the  asterion.  The  latter  coincides  with  the  position  of 
the  postero-lateral  fontanelle  in  early  life.  The  point  near  the 
anterior  part  of  the  parieto-mastoid  suture,  where  a  process  of 
the  parietal  is  received  into  the  parietal  notch  of  the  mastoid,  is 
known  as  the  entomion. 

The  lateral  region  is  divided  by  the  zygomatic  arch  into  the 
temporal  and  zygomatic  fossae,  the  former  being  above  the  arch, 
and  the  latter  within  and  below  it. 

The  temporal  fossa  is  bounded  above  by  the  superior  temporal 
ridges  of  the  frontal  and  parietal,  and  below  by  the  upper  border 
of  the  zygomatic  arch  externally,  and  the  infratemporal  crest  of 
the  great  wing  of  the  sphenoid  internally.  It  is  formed  by  five 
bones,  as  follows  :  in  front  by  the  orbital  process  of  the  malar, 
above  by  the  lower  portions  of  the  frontal  and  parietal,  and 
below  by  the  temporal  division  of  the  outer  surface  of  the  great 
wing  of  the  sphenoid  and  the  squamous  portion  of  the  temporal. 
The  place  where  the  parietal,  frontal,  great  wing  of  the  sphenoid, 
and  squamous  portion  of  the  temporal  are  related  to  one  another, 
and  more  particularly  the  region  of  the  spheno-parietal  suture, 
is  known  as  the  pterion,  which  coincides  with  the  position  of 
the  antero-lateral  fontanelle  of  early  life.  In  this  situation  a  Wor- 
mian bone  is  sometimes  present,  called  the  epipteric  bone.  The 
temporal  fossa  gives  origin  to  the  temporal  muscle  as  high  as  the 
inferior  temporal  ridge,  and  the  temporal  fascia,  which  covers 
that  muscle,  is  attached  to  the  superior  temporal  ridge. 

The  zygomatic  fossa  is  situated  below  the  level  of  the  infra- 
temporal crest  of  the  sphenoid.  It  is  bounded  externally  by  the 
ramus  of  the  inferior  maxilla  and  the  inner  surface  of  the  zygomatic 
arch,  and,  between  the  two,  it  communicates  with  the  exterior  by 
means  of  the  sigmoid  notch.  Internally  it  is  bounded  by  the 
external  pterygoid  plate  of  the  sphenoid.  Superiorly  it  is  limited 
by  the  zygomatic  surface  of  the  great  wing  of  the  sphenoid 
below  the  infratemporal  crest,  where  it  presents  the  foramen 
ovale  and  foramen  spinosum,  and  by  a  small  part  of  the 
squamous  portion  of  the  temporal.  Anteriorly  its  wall  is  formed 
by  the  lower  portion  of  the  internal  surface  of  the  malar  and  the 
zygomatic  surface  of  the  superior  maxilla,  which  latter  presents 
the  openings  of  the  posterior  dental  canals.     Its  superior  limit  is 


THE  BONES  OF  THE  HEAD 


133 


the  infratemporal  crest  of  the  sphenoid,  the  inferior  limit  being  the 
molar  portion  of  the  alveolar  border  of  the  superior  maxilla  and 
the  lower  border  of  the  external  pterygoid  plate. 

The  contents  of  the  fossa  are  as  follows :  the  coronoid  process 
of  the  inferior  maxilla  with  the  insertion  of  the  temporal  muscle  ; 
the  external  and  internal  pterygoid  muscles  ;  the  first  and  second 
parts  of  the  internal  maxillary  artery,  and  the  pterygoid  plexus  of 
veins  ;  the  inferior  maxillary  division  of  the  fifth  cranial  nerve  and 


Fronto-Malar  Suture 


Orbital  Plate  of  Frontal 
Glabella 


Fronto-nasal  Suture 
Fronto-maxill.  Suture 
Nasal  Bone  .  _ 
Nas.  P.  of  Sup.  Max  - 
Lachrjmal  Groove 
Orbital  Surf,  of- 
Lachrymal  Bone 


Great  Wing  of  Sphenoid 

,Spheno-niaxillary  Fissure 

/Back  Part  of  Infra-orb.  Groove 

/Spheno-maxillary  Fossa 

Infratemporal  Crest 
rSpheno-palat.  Foramen 

/        ,Zygom.  Surf,  of  Great 
y      Wing  of  Sphenoid 
Pterygo- maxillary 
Fissure 
Zygoma 

Preglenoid 
Tubercle 


'•Foramen  Ovale 
^^     Foram.  Spinosum 

-'";>_     Spine  of  Sphenoid 
Openings  of  Posterior 
Dental  Canals 


External  Pterygoid  Plate  of 
Sphenoid 


Incisor  Fossa 

Canine  Fossa 


'        '      Hamular  Process 

Tuberosity  of  Palate  Bone 
Tuberosity  of  Superior  Maxilla 


Fig.  81. — Thk  Zygomatic  and  Spheno-Maxili.ary  Foss/F.. 


its  branches,  together  with  the  otic  (Arnold's)  ganglion  ;  the  chorda 
tympani  nerve  ;  and  the  spheno-mandibular  ligament. 

The  foramina  which  communicate  with  the  fossa  are  as  follows  : 
the  foramen  ovale  ;  the  foramen  spinosum ;  the  openings  of  the 
posterior  dental  canals  ;  and  the  inferior  dental  foramen. 

The  fossa  pr('.scnts  two  fissures — spheno-maxillary  and  pterygo- 
maxillary. 

The  spheno-maxillary  fissure  lies  horizontally  between  the  great 
wing  of   the  sphenoid  and  the  superior  maxilla.     Externally  it  is 


134  A  MANUAL  OF  ANATOMY 

closed,  as  a  rule,  by  the  malar,  but  sometimes  by  the  great  wing  of 
the  sphenoid,  which  may  here  articulate  with  the  superior  maxilla. 
Internally  it  is  bounded  by  the  zygomatic  surface  of  the  orbital 
process  of  the  palate  bone.  The  fissure  leads  into  the  orbit,  and 
transmits  the  superior  maxillary  nerve  to  become  the  infra- 
orbital, the  infra  -  orbital  vessels,  the  temporo  -  malar  or  orbital 
branch  of  the  superior  maxillary  nerve,  the  orbital  branches  of 
Meckel's  ganglion,  and  a  communicating  vein  which  passes  between 
the  inferior  ophthalmic  vein  and  the  pterygoid  plexus. 

The  pterygo-maxillary  fissure  lies  vertically  between  the  anterior 
border  of  the  pterygoid  process  of  the  sphenoid  and  the  posterior 
border  of  the  superior  maxilla,  at  their  upper  ends.  Interiorly  the 
fissure  is  closed  by  the  approximation  of  the  bones  forming  its  lips, 
a  part  of  the  tuberosity  of  the  palate  bone  usually  intervening 
between  them,  though  direct  articulation  sometimes  takes  place 
between  the  pterygoid  process  and  the  superior  maxilla.  Internally 
the  fissure  is  bounded  by  the  perpendicular  plate  of  the  palate  bone. 
It  transmits  the  internal  maxillary  artery  to  the  spheno-maxillary 
fossa.  The  pterygo-maxillary  fissure  meets  the  spheno-maxillary 
fissure  at  a  right  angle,  and  situated  deeply  within  this  angle  is 
the  spheno-maxillary  fossa. 

The  boundaries  of  the  spheno-maxillary  fossa  are  as  follows  : 
anteriorly,  the  zygomatic  surface  of  the  superior  maxilla  at  its 
inner  and  back  part  superiorly ;  posteriorly,  the  base  of  the 
pterygoid  process  of  the  sphenoid,  and  the  lower  and  inner  part 
of  the  anterior  surface  of  its  great  wing;  internally,  the  perpen- 
dicular plate  of  the  palate  bone,  with  its  orbital  and  sphenoidal 
processes  ;  and  superiorly,  the  under  surface  of  the  body  of  the 
sphenoid.  The  contents  of  the  fossa  are  the  third  part  of  the 
internal  maxillary  artery,  the  superior  maxillary  nerve,  and  the 
spheno-palatine  or  Meckel's  ganglion,  along  with  their  branches. 
Two  fissures  communicate  with  this  fossa,  namely,  the  spheno- 
maxillary, leading  into  the  orbit,  and  the  pterygo-maxillary, 
opening  into  the  zygomatic  fossa.  It  also  communicates  with 
the  superior  meatus  of  the  nose  by  means  of  the  spheno-palatine 
foramen  on  its  inner  wall. 

The  foramina  which  open  into  the  spheno-maxillary  fossa  are  as 
follows  :  three  on  the  posterior  wall,  in  the  following  order  from  above 
downwards,  and  from  without  inwards  :  the  foramen  rotundum 
for  the  superior  maxillary  nerve,  the  Vidian  or  pterygoid  canal  for 
the  Vidian  nerve  and  vessels,  and  the  pterygo-palatine  canal  for 
the  pharyngeal  nerve  and  pterygo-palatine  vessels.  On  the 
internal  wall  is  the  spheno-palatine  foramen  for  the  internal  branches 
of  Meckel's  ganglion  and  the  spheno-palatine  artery.  Inferiorly  is 
the  opening  of  the  posterior  palatine  canal  for  the  great  or  anterior 
descending  palatine  nerve  and  the  descending  palatine  artery. 
In  this  situation  there  may  also  be  the  openings  of  the  posterior  and 
external  accessory  palatine  canals  for  the  posterior  and  external 
descending  palatine  nerves,  but  these  openings  usually  branch  off 


THE  BONES  OF  THE  HEAD  135 

from  the  main  canal.  Anteriorly  is  the  spheno-maxillary  fissure. 
Externally  the  fossa  communicates  with  the  zygomatic  fossa  through 
the  pterygo-maxillary  fissure. 


5.  The  Inferior  Region. 

The  inferior  region  or  external  base  (norma  basilaris),  from  which 
the  inferior  maxilla  is  excluded,  is  limited  in  front  by  the  central 
portions  of  the  alveolar  borders  of  the  superior  maxillae,  and  behind 
by  the  superior  curved  lines  of  the  occipital.  At  eitfier  side  it  is 
limited  by  the  lateral  portion  of  the  alveolar  border  of  the  superior 
maxilla,  and  by  a  line  connecting  the  tuberosity  of  that  bone  with 
the  lateral  angle  of  the  tabular  part  of  the  occipital.  It  is  very 
irregular,  and  presents  three  divisions — anterior,  middle,  and 
posterior. 

The  anterior  division  forms  the  hard  palate,  and  resembles 
a  horseshoe.  It  is  bounded  in  front  and  laterally  by  the  alveolar 
borders  of  the  superior  maxillge,  and  behind  by  the  posterior 
borders  of  the  horizontal  plates  of  the  palate  bones.  The  posterior 
border  presents  in  the  middle  line  the  posterior  nasal  spine  in  two 
halves,  from  which  the  azygos  uvulae  muscle  arises.  At  either 
side  of  this  it  is  sharp  and  concave  for  the  attachment  of  the  soft 
palate.  The  bones  forming  the  hard  palate  are  the  palatal  pro- 
cesses of  the  superior  maxillae  over  the  anterior  three-fourths,  and 
the  horizontal  plates  of  the  palate  bones  over  the  posterior  fourth. 
The  surface  is  vaulted,  and  is  intersected  by  two  sutures,  middle 
palatal  and  transverse  palatal.  The  middle  palatal  suture  extends 
from  the  alveolar  point  to  the  posterior  nasal  spine,  and  indicates 
the  meeting  of  the  palatal  plates  of  the  superior  maxillae  and  palate 
bones  of  opposite  sides.  The  transverse  palatal  suture  crosses 
the  middle  one  at  right  angles  about  h  inch  in  front  of  the  posterior 
border,  and  externally  it  turns  backwards  to  end  at  the  posterior 
palatine  foramen.  It  indicates  the  meeting  of  the  palatal  process 
of  the  superior  maxilla  and  the  horizontal  plate  of  the  palate  bone 
of  either  side. 

In  young  skulls  two  additional  sutures  are  present,  called 
maxillo-premaxillary,  each  of  which  extends  from  the  posterior 
part  of  the  anterior  palatine  fossa  to  the  interval  between  the 
lateral  incisor  and  canine  teeth.  Each  of  these  sutures  corre- 
sponds with  the  place  of  junction  of  the  maxilla  proper  and  the 
premaxilla. 

The  hard  palate  presents  several  openings.  At  the  anterior 
extremity  of  the  middle  {)alatal  suture  is  the  diamond-shaped 
anterior  palatine  fossa.  Within  this  are  four  oj^enings,  two  being 
placed  laterally,  one  at  either  side,  called  the  foramina  of  Stensen 
(incisor  foramina),  and  two  in  the  median  line  in  the  intermaxillary 
suture,  called  the  foramina  of  Scarpa,  anterior  and  posterior  respec- 
tively.    Each  of  the  former  transmits  a  branch  of  the  descending, 


136 


Fig. 


29         28  27         26 

82. — The  External  Base  of  the  Skull. 


Ant.  Palatine  Fossa 

Post.  Nasal  Spine 

Post.  Border  of  Vomer 

Facial  Surf,  of  Sup.  Maxilla 

Hamular  Process  of  Int.  Pterygoid 
Plate  of  Sphenoid 

Pterygoid  Fossa 

Ext.  Pterygoid  Plate 

Zygomatic  Process  of  Malar 

Zygoma  of  Temporal 

Pharyngeal  Tubercle  (pointer 
crosses  Foram.  Lacerum  Med.) 

Kustachian  Groove 

Groove     for     Chorda     Tympani 
Nerve 

Petrous  Portion  of  Temporal  (Ori- 
gin of  Levator  Palati) 

Carotid  Foramen 

Ext.  Auditory  Meatus 

Ext.  Auditory  Process  • 

Basion 


Mastoid  Process 

Jugular  Foramen 

Ant.  Condylar  Foramen 

Digastric  Groove 

Occipital  Groove 

Post.  Condylar  Foramen 

Sup  Curved  Line  of  Occipital 

Inf.  Curved  Line 

Fxt.  Occipital  Crest 

Ext.  Occipital  Protuberance 

Opisthion 

Foramen  Magnum 

Right  Occipital  Condyle 

Foram.  Lacerum  Medium 

at  + 
Vaginal  Proc.  of  Tymp.  Plate 
Mastoid  Foramen 
Stylo-Mastoid  Foramen 
Styloid  Process 
Tympanic  Plate  (Post,  part  of 

Glenoid  Fossa) 


Spinous  Proc.  of  Sphenoid 
Ant.  part  of  Glenoid  Fossa 
Foramen  Spinosum 
Foramen  Ovale 
Foramen  Vesalii 
Preglenoid  Tubercle 
Eminentia  Articularis 
Zygomatic  Fossa 
Infratemporal  Crest 
Temporal  Division   of  (Jreat 

Wing  of  Sphenoid 
Spheno-Maxillary  Fissure 
Tuberosity  of  Sup.  Maxilla 
Ext.  Access.  Palat.  Foramen 
Post.  Access.  Palat.  Foramen 
Post.  Palatine  Foramen 
Right  Post.  Naris  (pointer  crosses 

ridge  for  Tensor  Palati) 
Groove  for  Descend.  Palat.  Artery 
Horiz.  Plate  of  Palate  Bone 
Palat.  Proc.  of  Sup.  Maxilla 


THE  BONES  OF  THE  HEAD  ■  137 

palatine  artery  from  the  palate  to  the  nasal  fossa,  whilst  each  of 
the  latter  transmits  the  naso-palatine  nerve  from  the  nasal  fossa 
to  the  hard  palate,  the  anterior,  which  usually  opens  from  the  left 
nasal  fossa,  containing  the  left  nerve,  and  the  posterior,  which 
usually  opens  from  the  right  nasal  fossa,  containing  the  right 
nerve.  Internal  to  the  last  molar  alveolus  at  either  side  is  the 
posterior  palatine  foramen,  which  is  the  outlet  of  the  posterior 
palatine  or  palato-maxillary  canal,  and  through  which  the  great 
or  anterior  descending  palatine  nerve  and  the  descending  palatine 
vessels  pass.  Leading  forwards  from  this  foramen  there  is  a  groove 
for  the  transmitted  structures.  A  little  behind  the  posterior 
palatine  foramen  is  the  posterior  accessory  palatine  foramen  for 
the  posterior  de  cending  palatine  nerve,  and  outside  this  is  the 
external  accessory  palatine  foramen  for  the  external  descending 
palatine  nerve,  but  the  last-named  foramen  is  inconstant.  Besides 
the  foregoing  openings,  there  are  a  number  of  nutrient  foramina. 
Over  its  anterior  three-fourths  the  hard  palate  presents  several 
depressions  for  the  palatal  mucous  glands,  and  extending  inwards 
from  the  back  part  of  the  posterior  palatine  foramen  at  either 
side  is  a  transverse  ridge  which  gives  partial  insertion  to  the  tensor 
palati  muscle. 

The  middle  division  extends  from  the  posterior  border  of  the 
hard  pala  e  to  a  transverse  line  on  a  level  with  the  anterior  margin 
of  the  foramen  magnum.  Laterally  it  is  limited  by  a  line  extending 
from  the  tuberosity  of  the  superior  maxilla  to  the  styloid  process 
of  the  temporal.  It  is  on  a  higher  level  than  the  anterior  division, 
and  its  central  or  basilar  part  is  known  as  the  guttural  fossa. 
The  bones  forming  it  at  either  side  are  the  tuberosity  of  the 
palate  bone,  the  pterygoid  process,  and  a  small  part  of  the 
great  wing,  of  the  sphenoid,  and  the  inferior  surface  of  the  petrous 
portion  of  the  temporal.  The  central  part  is  formed  by  the 
basilar  process  of  the  occipital,  the  body  and  vaginal  processes 
of  the  sphenoid,  the  superior  border  and  alae  of  the  vomer,  and 
the  sphenoidal  processes  of  the  palate  bones. 

Anteriorly  it  presents  the  posterior  nares,  already  described,  and 
at  either  side  of  these  openings  is  the  pterygoid  fossa,  which  is 
bounded  internally  by  the  internal,  and  externally  by  the  external, 
pterygoid  plate  of  the  sphenoid,  the  fossa  being  completed  in- 
feriorly  by  the  tuberosity  of  the  palate  bone. 

In  a  line  extending  backwards  and  outwards  from  the  external 
pterygoid  plate  to  the  styloid  process  the  following  parts  are 
seen,  in  order  from  before  backwards:  foramen  ovale;  foramen 
spinosum  ;  spinous  process  of  the  sphenoid ;  internal  border 
of  tlie  iym;)anic  plate  of  the  temporal,  forming  posteriorly  the 
vaginal  process :  and  styloid  process.  Inside  the  foregoing  line 
anteriorly  is  the  Eustachian  groove,  which  lies  obliquely  between 
the  great  wing  of  the  sphenoid  and  the  a})ical  part  of  the  petrous 
j)ortion  of  the  temporal.  This  groove  lodges  the  cartilaginous  part 
of  the  Eustachian  tube,  and,  when  followed  outwards  and  backwards, 


13S  A  MANUAL  OF  ANATOMY 

it  leads  to  the  Eustachian  canal  in  the  angle  between  the  squamous 
and  petrous  portions  of  the  temporal. 

On  either  side  of  the  basilar  process  of  the  occipital  is  the  foramen 
laeerum  medium,  also  known  as  the  sphenotic  foramen  from  its 
relation  to  the  sphenotic  portion  (lingula)  of  the  sphenoid.  It  hes 
between  the  basilar  process,  the  apex  of  the  petrous  portion  of  the 
temporal,  and  the  great  wing  of  the  sphenoid  near  the  root  of  the 
pter^-goid  process.  In  the  recent  state  it  is  here  closed  b}'  fibrous 
tissue,  which  is  pierced  by  a  meningeal  branch  of  the  ascending 
pharyngeal  arter^^  and  one  or  more  emissary  veins  from  the  cavern- 
ous sinus. 

In  a  line  extending  backwards  and  outwards  from  the  foramen 
laeerum  medium  are  the  following  markings  on  the  inferior  surface 
of  the  petrous  portion  of  the  temporal  :  the  rough  surface  from 
which  the  levator  palati  arises  :  the  carotid  foramen,  which 
transmits  the  internal  carotid  arter\"  and  the  ascending  branch 
of  the  superior  cer\"ical  ganghon  of  the  s\Tnpathetic  :  a  minute 
foramen,  on  the  posterior  wall  of  the  vertical  portion  of  the  carotid 
canal,  for  the  tjinpanic  branch  of  the  carotid  s^mipathetic  plexus 
and  t^Tnpanic  branch  of  the  internal  carotid  artery:  the  jugular 
fossa,  which  forms  part  of  the  jugular  foramen  :  the  tympanic 
canaliculus,  on  the  ridge  between  the  carotid  foramen  and  jugular 
fossa,  for  the  t^-mpanic  branch  (Jacobson's  ner\^e)  of  the  glosso- 
phar\-ngeal  and  the  tympanic  branch  of  the  ascending  phar\T:igeal 
arter\- :  and  the  auricular  canaliculus,  on  the  outer  wall  of  the 
jugular  fossa,  for  the  auricular  branch  (Arnold's  ner\-e)  of  the 
pneumogasrric.  Between  the  petrous  portion  of  the  temporal 
and  the  jugular  process  of  the  occipital  is  the  foramen  laeerum 
posterius  or  jugular  foramen,  which  lodges  the  commencement  of 
the  internal  jugular  vein,  and  transmits  the  following  structures  : 
the  glosso-phar^mgeal.  pneumogastric,  and  spinal  accessor^"  ner^^es : 
the  inferior  petrosal  sinus  ;  and  meningeal  branches  of  the  ascending 
phar\-ngeal  and  occipital  arteries. 

External  to  the  front  of  the  occipital  condyle  is  the  anterior 
condylar  foramen  for  the  h\-poglossal  nerve  and  a  meningeal  branch 
of  the  ascending  pharyngeal  arter\".  The  imder  surface  of  the 
basilar  process  of  the  occipital  presents  the  pharyngeal  tubercle. 

The  posterior  division  is  limited  in  front  by  a  transverse  line 
on  a  level  with  the  anterior  margin  of  the  foramen  magnum, 
and  behind  bv  the  external  occipital  protuberance  and  the 
superior  cur\-ed  line  at  either  side.  It  is  formed  b}-  the  supra- 
occipital  and  condvlar  portions  of  the  occipital  and  the  mastoid 
portions  of  the  temporal  bones. 

In  the  middle  line  is  the  foramen  magnum,  which  transmits 
the  mediilla  oblongata  and  its  membranes,  the  spinal  accessory 
nerves,  the  vertebral  arteries,  and  the  anterior  and  posterior 
spinal  arteries.  The  centre  of  the  anterior  margin  of  the 
foramen  magnum  is  known  as  the  basion,  and  the  centre  of 
the    posterior    margin    as    the    opisthion.      Proceeding    outwards 


THE  BONES  OF  THE  HEAD  I39 

from  this  foramen  are  the  occipital  condyle,  jugular  process, 
occipital  groove  for  the  occipital  artery,  digastric  groove  for  the 
posterior  belly  of  the  digastric,  and  the  mastoid  process.  Behind 
the  occipital  condyle  is  the  posterior  condylar  fossa,  in  which 
there  may  be  a  posterior  condylar  foramen  for  the  passage  of 
an  emissary  vein  from  the  lateral  sinus.  Behind  the  foramen 
magnum  is  the  supra-occipital  portion  of  the  occipital,  which  presents 
the  external  occipital  crest  in  the  median  line,  and  the  inferior  curved 
line  extending  outwards  on  either  side  from  its  centre. 


The  Interior  of  the  Cranium. 

A  sagittal  or  antero-posterior  section  of  the  skull  a  little  to  one 
side  of  the  median  plane  shows  the  septum  nasi  already  described. 
Along,  and  at  either  side  of,  the  vault  of  the  cranium  is  the  groove 
for  the  superior  longitudinal  venous  sinus,  which  extends  from 
before  backwards,  and  on  either  side  of  its  parietal  portion  are  the 
Pacchionian  depressions.  The  internal  openings  of  the  parietal 
foramina  may  be  seen,  as  well  as  the  branching  system  of  menin- 
geal grooves,  and  digitate  impressions.  The  basi-cranial,  basi- 
facial,  and  basi-bregmatic  axes  are  to  be  studied  from  this  section. 
The  basi-cranial  axis  represents  a  line  drawn  upwards  and  forwards 
from  the  basion  to  the  spheno-ethmoidal  suture.  The  basi-facial 
axis  corresponds  with  a  line  drawn  from  the  spheno-ethmoidal 
suture  to  the  subnasal  point.  The  angle  formed  by  these  two 
axes  is  known  as  the  cranio-facial  angle.  The  basi-bregmatic 
axis  represents  a  line  drawn  vertically  from  the  basion  to  the 
bregma. 

The  most  instructive  coronal  or  transverse  section  is  one  made 
in  the  plane  of  the  basi-bregmatic  axis.  Such  a  section  gives 
important  views  of  the  parts  within  the  petrous  portion  of  the 
temporal,  such  as  the  external  auditory  meatus,  tympanum,  and 
vestibule. 

When  a  horizontal  section  has  been  made  on  a  level  with  the  occi- 
pital point  and  the  most  prominent  part  of  the  glabella,  the  vaulted 
roof  of  the  cranium  is  removed.  This  is  called  the  calvaria, 
or  skull-cap,  and  it  is  formed  by  portions  of  the  frontal,  parietals, 
squamous  portions  of  the  temporals,  and  occipital.  The  outer 
plate  is  strong,  except  over  the  temporal  region,  but  the  inner  is 
brittle  and  readily  cracked,  from  which  circumstance  it  is  known 
as  the  vitreous  (glassy)  plate.  Between  the  two  plates  there  is 
cancellated  tissue,  here  called  diploe.  The  interior  of  the  calvaria 
presents  branching  meningeal  grooves,  digitate  impressions,  and 
along  the  middle  line  the  groove  for  the  superior  longitudinal  venous 
sinus,  with  depressions  at  either  side  for  the  Pacchionian  bodies. 
The  openings  of  the  parietal  foramina  may  be  noted. 


140 


A  MANUAL  OF  ANATOMY 


20        19  18      17  16 15  14 


Fig.  83. — Sagittal  Section  of  the  Skull  to  the  Right  of  the  Median 

Plane. 

F,  Frontal ;   P,  Parietal ;   O,  Occipital ;   T,  Temporal. 


I. 

Coronal  Suture 

II 

2. 

Anterior  and  Posterior  Me- 

12 

ningeal  Grooves 

13 

3- 

Lambdoid  Suture 

14. 

4- 

Hiatus  Subarcuatus 

^S- 

5- 

Sigmoid  Groove 

16. 

6. 

Inion    (External     Occipital 

17- 

Protuberance) 

18. 

7- 

Asterion 

8. 

Sigmoid  Groove 

19. 

9- 

Aqueductus  Vestibuli 

20. 

Jugular  Foramen 

21. 

Anterior  Condylar  Foramen 

Internal  Auditory  Meatus 

Styloid  Process 

Dorsum  Sellre 

Sella  Turcica 

External  Pterygoid  Plate 

Hamular  Process 

Superior  Turbinate  Process 

of  Ethmoid 
Superior  Meatus 
Inferior  Meatus 
Right  Superior  Maxilla 


Anterior  Nasal  Spine 
Inferior  Turbinate  Bone 
Middle  Meatus 
Inferior   Turbinate   Process 

of  Ethmoid 
Infundibulum 
Nasal  Bone 

Right  Sphenoidal  Sinus 
Right  Frontal  Sinus 
Crista  Galli 
Optic  Foramen 
Pterion 


The  Internal  Base  of  the  Skull. 

The  internal  base  forms  the  floor  of  the  cranial  cavity,  and  is  of 
very  irregular  outline  and  thickness.  The  thickest  and  densest 
parts  are  the  petrous  portions  of  the  temporals.  The  mastoid 
portion  of  the  temporal  and  the  basilar  part  of  the  occipital  are  also 
thick.  The  thinnest  parts  are  the  cribriform  plate  of  the  ethmoid 
and  the  orbital  plates  of  the  frontal,  but  the  central  portions  of  the 
cerebellar  fossae  of  the  occipital  are  also  thin,  sometimes  remarkably 
so.  The  interior  of  the  base  is  divided  into  three  fossae — anterior, 
middle,  and  posterior. 

Anterior  Fossa. — The  floor  of  this  fossa  is  formed  by  the  orbital 


THE  BONES  OF  THE  HEAD  141 

plates  of  the  frontal,  the  cribriform  plate  of  the  ethmoid,  and  the 
small  wings,  jugum  sphenoidale,  and  ethmoidal  spine  of  the  sphenoid. 
It  is  limited  posteriorly  by  the  posterior  or  Sylvian  border  of  the 
small  wing  of  the  sphenoid  at  either  side,  and  by  the  limbus  sphen- 
oidalis  in  the  centre.  It  is  subdivided  into  a  central  and  two  lateral 
parts. 

The  central  portion,  which  is  depressed,  is  formed  by  the  cribri- 
form plate  of  the  ethmoid  and  the  ethmoidal  spine  and  jugurn 
of  the  sphenoid.  In  the  middle  line  it  presents  the  crista  galli, 
which  gives  attachment  to  the  falx  cerebri.  In  front  of  this  is  the 
foramen  caecum,  which,  when  pervious,  transmits  an  emissary  vein 
passing  between  the  intracranial  superior  longitudinal  sinus  and  the 
veins  of  the  roof  of  the  nose.  At  each  side  of  the  crista  galli  are 
the  nasal  slit  for  the  nasal  nerve  and  anterior  ethmoidal  artery  ; 
the  cribriform  foramina  for  the  filaments  of  the  olfactory  bulb  ; 
the  cranial  opening  of  the  anterior  ethmoidal  canal  for  the  anterior 
ethmoidal  artery  and  nasal  nerve ;  and  the  cranial  opening  of  the 
posterior  ethmoidal  canal  for  the  posterior  ethmoidal  artery  and 
spheno-ethmoidal  branch  of  the  nasal  nerve.  The  last  two  open- 
ings are  situated  at  the  outer  side  of  the  cribriform  plate,  external 
to  the  olfactory  groove  which  marks  it.  Directly  beneath  each 
half  of  the  cribriform  plate  is  the  corresponding  nasal  fossa. 

Each  lateral  portion  of  the  anterior  fossa  is  irregularly  convex,  and 
forms  the  roof  of  the  orbit.  It  is  formed  by  the  orbital  plate  of  the 
frontal  and  the  small  wing  of  the  sphenoid.  It  is  very  thin,  and, 
except  over  the  small  wing  of  the  sphenoid,  it  presents  digitate 
impressions  for  the  convolutions  of  the  orbital  surface  of  the  frontal 
lobe  of  the  cerebrum,  which  it  supports.  The  sutures  in  the  anterior 
fossa  are  the  fronto-ethmoidal,  fronto-sphenoidal,  and  spheno- 
ethmoidal. 

Middle  Fossa. — This  fossa  is  on  a  lower  level  than  the  anterior. 
It  is  bounded  in  front  by  the  posterior  or  Sylvian  border  of  the  small 
wing  of  the  sphenoid  at  either  side,  and  by  the  limbus  sphenoidalis 
in  the  centre.  Behind  it  is  limited  by  the  superior  border  of  the 
petrous  portion  of  the  temporal  at  either  side,  and  by  the  dorsum 
sella;  of  the  sphenoid  in  the  centre.  It  presents  a  central  and  two 
lateral  divisions.  The  central  division  is  formed  by  the  superior  sur- 
face of  the  body  of  the  sphenoid  posterior  to  the  limbus  sphenoidalis. 
Each  lateral  division,  which  is  much  depressed,  is  formed  anteriorly 
by  the  superior  surface  of  the  great  wing  of  the  sphenoid,  externally 
by  part  of  the  squamous  portion  of  the  temporal,  and  posteriorly 
by  the  superior  surface  of  the  petrous  portion  of  that  bone.  It  lodges 
the  temporo-sphenoidal  lobe  of  the  cerebrum,  and  it  presents  the 
following  sutures :  the  spheno-parietal  ;  squamous  or  squamo- 
parietal  ;  squamo-sphcnoidal  ;  and  petro-sphenoidal. 

The  central  division  j^resents  the  following  parts :  the  optic 
groove  and  olivary  eminence  for  the  optic  commissure  ;  the  optic 
foramen  of  each  sid(;  ior  the  optic  nerve  and  ophthalmic  artery; 
the  anterior  clinoid    process   of  each  side ;    the   sella   turcica   or 


142  A  MANUAL  OF  ANATOMY 

pituitary  fossa  for  the  pituitary  body;  the  cavernous  or  carotid 
groove,  at  either  side  of  the  sella  turcica,  for  the  cavernous 
venous  sinus  and  internal  carotid  artery,  the  latter  being  accom- 
panied by  the  cavernous  sympathetic  plexus  of  nerves,  and  having 
the  sixth  cranial  nerve  on  its  outer  side ;  the  middle  clinoid 
process  of  each  side  (sometimes  connected  with  the  anterior, 
which  it  faces) ;  the  dorsum  sellse  ;  the  posterior  clinoid  process 
of  each  side,  at  either  lateral  angle  of  the  dorsum  sellae  ;  and  the 
notch  for  the  sixth  cranial  nerve,  on  each  side  of  the  dorsum 
sellge  a  little  below  the  posterior  clinoid  process.  The  central 
division  corresponds  with  the  interpeduncular  region  at  the  base  of 
the  cerebrum. 

Each  lateral  division  is  marked  by  meningeal  grooves  and 
digitate  impressions,  and  presents  the  following  openings :  the 
sphenoidal  fissure,  or  foramen  lacerum  anterius  or  orbitale,  for  the 
third  cranial  nerve,  the  fourth,  the  three  branches  of  the  ophthalmic 
division  of  the  fifth  (namely,  frontal,  lachrymal,  and  nasal),  and 
the  sixth  cranial  nerves,  the  sympathetic  root  of  the  ciliary  ganglion, 
the  superior  and  inferior  ophthalmic  veins,  the  orbital  branch  of 
the  middle  meningeal  artery,  and  a  portion  of  the  dura  mater  to 
form  the  orbital  periosteum  ;  the  foramen  rotundum,  leading  to  the 
spheno-maxillary  fossa,  and  transmitting  the  superior  maxillary 
division  of  the  fifth  cranial  nerve  ;  the  foramen  ovale,  leading  to  the 
zygomatic  fossa,  and  transmitting  the  inferior  maxillary  division 
and  the  motor  root  of  the  fifth  cranial  nerve,  the  small  meningeal 
artery,  an  emissary  vein  from  the  cavernous  sinus,  and  occasionally 
the  small  superficial  petrosal  nerve  ;  the  foramen  Vesalii  (inconstant), 
leading  to  the  scaphoid  fossa  at  the  root  of  the  internal  pterygoid 
plate,  or  to  the  pterygoid  fossa  external  to  the  scaphoid  fossa,  and 
transmitting  an  emissary  vein  from  the  cavernous  sinus ;  the 
foramen  spinosum,  leading  to  the  zygomatic  fossa,  and  transmitting 
the  middle  meningeal  artery  and  a  recurrent  branch  of  the  inferior 
maxillary  nerve  ;  and  the  foramen  lacerum  medium  or  sphenotic 
foramen,  situated  between  the  basilar  process  of  the  occipital,  the 
apex  of  the  petrous  portion  of  the  temporal,  and  the  great  wing  of 
the  sphenoid  near  the  root  of  the  pterygoid  process.  The  posterior 
opening  of  the  Vidian  canal,  which  leads  to  the  spheno-maxillary 
fossa  and  transmits  the  Vidian  nerve  and  artery,  is  to  be  found 
on  its  anterior  wall,  while  the  carotid  canal  for  the  internal  carotid 
artery,  with  a  plexus  of  sympathetic  nerve  fibres,  opens  on  its 
external  wall. 

The  superior  surface  of  the  petrous  portion  of  the  temporal 
presents  the  following  markings  :  the  Gasserian  depression,  near 
the  apex,  for  the  Gasserian  ganglion  ;  the  hiatus  Fallopii,  to  which 
a  groove  conducts  for  the  great  superficial  petrosal  nerve  and 
the  petrosal  branch  of  the  middle  meningeal  artery  ;  (within  this 
opening  there  may  be  a  small  one  for  the  external  superficial 
petrosal  nerve)  ;  the  accessory  hiatus,  to  which  a  groove  conducts, 
for  the  small  superficial  petrosal  nerve  ;   the  eminentia  arcuata, 


THE  BONES  OF  THE  HEAD 


143 


30      29     / 


Fig.  84. — The  Internal  Base  of  the  Skull. 

(The  Superior  Surface  of  the  Petrous  Portion  of  the  Right  Temporal  Bone  has  been  removed  lo 
expose  the  Internal  Auditory  Meatus  and  Semicircular  Canals.) 


Foramen  Caecum 

Crista  Galli 

Kthmoidal  Spineof  Sphenoid 

Jugum  Sphenoidale 

Anterior  Fossa 

Limbus  Sphenoidalis 

Optic  (jroove 

Olivary  Eminence 

.Sylvian     Border    of    Small 

Wing  of  .Sphenoid 
Anterior  Clinoid  Process 
Middle  Clinoid  Process 
Sella  Turcica 
Posterior  Clinoid  Process 
Dorsum  .Sella; 
Basilar  firoove 
Groove    for    Inf.      Petrosal 

Sinus 
Superior  Semicircular  Canal 
Kxternal  Semicircular  Canal 


jg.  Posterior  Semicircular  Canal 

20.  Internal    Auditory    Meatus 

(laid  open) 

21.  Opening  of  Internal  Audi- 

tory Meatus 

22.  Anterior  Condylar  Foramen 

23.  Basion 

24.  Groove  for  Lateral  Sinus 

25.  Vermiform  Fossa 

26.  Torcular  Herophili 

27.  Int.  Occipital  Protuberance 

28.  Internal  Occipital  Crest 

29.  Opisthion 

30.  Cerebral  Fossa 

31.  Cerebellar  Fossa 

32.  Jugular  Foramen 

33.  Sigmoid  Groove 

34.  Internal  Auditory  Meatus 

35.  Gasserian  Depression 

36.  Eminentia  Arcuata 


Hiatus  Fallopii 
Accessory  Hiatus 
Foramen  Lacerum  Medium 
Foramen  Spinosum 
Foramen  Ovale 
Middle  Fossa 
Foramen  Vesalii 
Lingula  of  .Sphenoid 
Parietal  Bone 
Coronal  Suture 
Cavernous  Groove 
Pterion 

Foramen  Kotundum 
Orl)ital  Plate  of  Frontal 
Sphenoidal  Fissure 
Carotid  Notch 
Optic  Foramen 
Posterior  ICtliinoidal  Canal 
Anterior  Ethinoidal  Canal 
Left  Frontal  Sinus 


144  A  MANUAL  OF  ANATOMY 

which  coincides  with  the  position  of  the  superior  semicircular  canal 
of  the  internal  ear  ;  and  the  tegmen  tympani. 

Posterior  Fossa. — This  fossa  is  on  a  lower  level  than  the  middle.  It 
is  limited  in  front  by  the  dorsum  sellae  of  the  sphenoid  in  the  centre, 
and  the  superior  border  of  the  petrous  portion  of  the  temporal  at 
either  side.  Behind,  it  is  limited  by  the  internal  occipital  protuber- 
ance and  the  groove  at  either  side  for  the  lateral  venous  sinus, 
which  groove  also  marks  its  lateral  extent.  It  lodges  the  pons 
Varolii,  medulla  oblongata,  and  cerebellum.  The  bones  which 
form  it  are  as  follows  :  the  dorsum  sells  of  the  sphenoid  ;  the 
basilar,  condylar,  and  supra-occipital  portions  of  the  occipital  ;  the 
petrous  and  mastoid  portions  of  the  temporal  ;  and  the  postero- 
inferior  angle  of  the  parietal.  It  presents  the  following  sutures  : 
the  occipito-mastoid  ;  parieto-mastoid  ;  and  petro-basilar.  The 
following  parts  are  to  be  noted  :  the  basilar  groove,  the  upper 
part  of  which  lodges  the  pons  Varolii  and  basilar  artery,  whilst 
the  lower  part  contains  the  medulla  oblongata ;  the  foramen 
magnum,  which  transmits  the  medulla  oblongata  and  its  mem- 
branes, the  spinal  accessory  nerves,  and  the  vertebral,  anterior 
spinal,  and  posterior  spinal,  arteries;  the  anterior  condylar 
foramen,  on  either  side  of  the  foramen  magnum,  for  the  hypo- 
glossal nerve  and  a  meningeal  branch  of  the  ascending  pharyngeal 
artery;  the  internal  occipital  crest,  which  gives  attachment  to 
the  falx  cerebelli,  and  is  occasionally  grooved  for  the  occipital 
venous  sinus;  (near  the  foramen  magnum  this  crest  presents 
the  vermiform  fossa,  which  receives  a  part  of  the  vermiform 
process  of  the  cerebellum)  ;  the  cerebellar  fossae,  which  lodge  the 
hemispheres  of  the  cerebellum  ;  the  opening  of  the  internal  auditory 
meatus,  on  the  posterior  surface  of  the  petrous  portion  of  the 
temporal,  for  the  facial  and  auditory  nerves,  fars  intermedia  of 
Wrisberg,  and  auditory  artery  ;  the  aqueductus  vestibuli,  about 
J  inch  external  to  the  preceding,  for  a  small  artery  and  vein,  and 
the  ductus  endolymphaticus  ;  the  hiatus  subarcuatus,  representing 
the  floccular  fossa  of  early  life,  situated  close  to  the  superior  border 
of  the  petrous  portion,  about  midway  between  the  opening  of  the 
internal  auditory  meatus  and  aqueductus  vestibuli ;  and  the  jugular 
foramen  or  foramen  lacerum  posterius,  between  the  jugular  process 
of  the  occipital  and  petrous  portion  of  the  temporal. 

The  jugular  foramen  is  divided  into  three  compartments,  which 
lie  obliquely  from  behind  forwards  and  inwards.  The  postero- 
external compartment  transmits  the  lateral  venous  sinus  to 
become  the  internal  jugular  vein,  and  a  meningeal  branch  of  the 
ascending  pharyngeal  artery ;  the  middle  compartment  transmits 
the  glosso-pharyngeal,  pneumogastric,  and  spinal  accessory  nerves ; 
and  the  antero-internal  compartment  gives  passage  to  the  inferior 
petrosal  venous  sinus.  The  antero-internal  compartment  may 
be  more  or  less  completely  isolated  by  means  of  the  intrajugular 
process,  passing  between  the  occipital  and  the  petrous  portion  of 
the  temporal. 


THE  BONES  OF  THE  HEAD  145 

The  posterior  fossa  is  grooved  by  the  following  venous  sinuses  : 
the  lateral  sinus,  which  extends  from  the  internal  occipital  pro- 
tuberance to  the  jugular  foramen,  grooving  in  its  sinuous  course 
the  tabular  part  of  the  occipital,  the  postero-inferior  angle  of 
the  parietal,  the  mastoid  portion  of  the  temporal,  and  the  jugular 
process  of  the  occipital,  (opening  from  which  there  is  usually 
the  mastoid  foramen,  and  occasionally  the  posterior  condylar 
foramen)  ;  the  superior  petrosal  sinus,  which  grooves  the  superior 
border  of  the  petrous  bone  ;  the  inferior  petrosal  sinus,  along  the 
course  of  the  petro-basilar  suture  ;  and  the  occipital  sinus,  which 
sometimes  grooves  the  internal  occipital  crest. 

Wormian  Bones. 

The  Wormian  bones  (so  named  after  Wormius)  are  supernumerary 
bones  which  are  frequently  met  with  in  the  course  of  the  cranial 
sutures,  and  occasionally  in  the  face,  as  in  the  region  of  the  lachrymal 
bones,  and  at  the  outer  extremity  of  each  spheno-maxillary  fissure. 
From  their  position  in  the  course  of  sutures  they  are  known  as 
ossa  snttiraritm.  They  are  for  the  most  part  of  small  size  and 
triangular  outline,  and  are  hence  sometimes  spoken  of  as  ossa 
triqitetra.  They  are  usually  due  to  the  appearance  of  special 
ossific  centres.  Their  most  common  situation  is  along  the  course 
of  the  lambdoid  suture,  where  they  may  form  a  regular  chain. 
The  superior  angle  of  the  occipital  sometimes  persists  as  a  Wormian 
bone,  called  pre-interparietal,  which  may  be  double.  One  is  often 
found  between  the  antero-inferior  angle  of  the  parietal  and  great 
wing  of  the  sphenoid  in  the  region  of  the  pterion,  and  it  is  known 
as  the  epipteric  bone.  If  the  metopic  or  frontal  suture  is  persistent 
one  or  more  Wormian  bones  may  be  present  along  its  course,  and, 
if  at  the  upper  part,  they  may  give  rise  by  their  persistence  and 
union  to  a  bregmatic  bone.  In  the  condition  known  as  chronic 
hydrocephalus  Wormian  bones  of  large  size  are  present  in  great 
numbers  along  the  cranial  sutures. 

The  Skull  at  Birth. 

The  skull  at  birth  is  remarkable  for  its  large  size,  and  for  the 
great  development  of  the  cranium  as  compared  with  the  face.  The 
face  is  equal  to  one-eighth  of  the  cranium,  whereas  in  the  adult 
it  is  equal  to  one-half.  The  occipital,  parietal,  and  frontal  regions 
are  well  developed,  the  parietal  and  frontal  eminences  are  very 
conspicuous,  and  the  mastoid  i)rocesses  are  absent.  The  bones 
are  not  united  by  sutures,  but  are  connected  by  fibrous  tissue, 
continuous  with  the  periosteum  externally  and  dura  mater  inter- 
nally. Membranous  intervals  exist  between  the  angles  of  certain 
bones,  these  being  called  fontanelles  from  the  pulsation,  or  wclling- 
up  sensation,  which  can  be  felt  there.  They  are  six  in  number, 
two  being  placed  in  the  median  line,  anterior  and  posterior,  and 
two  at  oith(!r  side,  antoro-latoral  and  postero-lateral.  The  anterior 
fontanelle  is  situated  between  tlu;  antero-superior  angles  of  the 

10 


146 


A  MANUAL  OF  ANATOMY 


Anterior 


parietals  and  the  superior  angles  of  the  two  halves  of  the  frontal. 
It  is  large  and  diamond- shaped,  and  it  is  not  completely  closed, 
as  a  rule,  until  towards  the  end  of  the  second  year.  The  posterior 
fontanelle  is  situated  between  the  postero-superior  angles  of  the 
parietals  and  the  superior  angle  of  the  occipital.  It  is  small  and 
triangular,  and  is  usually  closed  at,  or  shortly  after,  birth,  but  the 
surrounding  bones  are  still  movable.  The  antero-lateral  and 
postero-lateral  fontanelles  correspond  with  these  angles  of  the 
parietal.      The   antero-lateral   is   situated  between  the   parietal, 

sphenoid,  frontal,  and 
squamous  portion  of  the 
temporal,  whilst  the 
postero-lateral  is  situated 
between  the  parietal,  occi- 
pital, and  mastoid  portion 
of  the  temporal.  For  the 
sagittal  fontanelle  of  the 
earlier  part  of  foetal  life, 
see  p.  63. 

The  skull  increases 
rapidly  in  size  during  the 
first  six  years,  and  a 
further  marked  increase 
commences  on  the  ap- 
proach of  puberty,  which 
is  associated  with  the 
development  of  the  air 
sinuses.  The  latter  in- 
crease affects  chiefly  the 
frontal  and  facial  regions. 
In  old  age  the  cranial 
bones  become  thinner, 
the  air  sinuses  under- 
go enlargement,  and  the 
sutures  show  indications 
of  obliteration. 

Characters    of    the 

Female  Skull. — The  bones 

The  mastoid  processes, 

The  frontal 


Posterior 

Fig.  85. — The  Skull  at  Birth,  showing  the 
Anterior  and  Posterior  Fontanelles, 
AND  the  Parietal  Eminences. 


are  smaller  and  smoother  than  in  the  male 

superciliary  ridges,  and  glabella  are  less  prominent. 

and  occipital  regions  are  not  so  well  developed  relatively  to  the 

parietal.     The  cranial  capacity  is  rather  less.     The  face  as  a  rule 

is  narrower,  and  bears  a  smaller  proportion  to  the  cranium. 


Racial  Peculiarities  of  the  Skull. 

In  comparing  the  skulls  of  different  races  attention  has  to  be  directed  to  the 
following  points  :  the  capacity  of  the  cranium,  its  circumference,  its  relative 
length,  breadth,  and  height,  the  degree  of  forward  elongation  of  the  jaws,  and 
the  shape  of  the  anterior  nasal  and  orbital  apertures.  The  cranial  capacity 
may  be  ascertained  by  filling  the  skull  with  shot,  or  various  kinds  of  seeds,  and 


THE  BONES  OF  THE  HEAD 


'47 


then  measuring  the  contents  in  a  graduated  vessel.  The  capacity  ranges  from 
about  60  to  no  cubic  inches,  and,  according  to  their  capacity,  skulls  are 
divided  into  three  groups,  namely,  mesocephalic,  with  a  capacity  of  about 
85  cubic  inches,  as  in  Chinese  ;  megacephalic,  with  a  capacity  exceeding 
that,  as  in  Europeans  ;  and  microcephalic,  with  a  capacity  under  it,  as  in 
Australians. 

In  regard  to  craniometry  the  following  craniometrical  terms  may  here  be 
summarized  : 

Alveolar  point  =  the  point  of  meeting  of  the  anterior  margins  of  the  alveolar 
borders  of  the  superior  maxillae. 

Antinion  =  the  most  prominent  point  of  the  glabella. 

Asterion=the  point  where  the  parieto-mastoid,  occipito-mastoid,  and  lamb- 
doid  sutures  meet. 

Auricular  point  =  the  centre  of  the  opening  of  the  external  auditory  meatus. 

Basion  =  the  centre  of  the  anterior  margin  of  the  foramen  magnum. 

Bregma  =  the  point  of  junction  of  the  sagittal  and  coronal  sutures. 

Dacryon  =  the  point  where  the  horizontal  fronto-maxillary  suture  meets  the 
vertical  lachrymo-maxillary  suture. 


Fig.   86. — The   Skull    at    Birth,    showing    the    Antero-lateral 
AND   Postero-lateral  Fontanelles, 


Entomion  =  the  point  near  the  anterior  part  of  the  parieto-mastoid  suture 
where  a  process  of  the  parietal  is  received  into  the  parietal  notch  of  the  mastoid. 

Glabella  =  a  point  midway  between  the  superciliary  ridges  of  the  frontal. 

Gnathion,  or  mental  point  =  the  middle  point  of  the  anterior  lip  of  the  lower 
border  of  the  inferior  maxilla. 

Gonion  =  the  outer  side  of  the  angle  of  the  inferior  ma.xilla. 

Inion  =  the  external  occipital  protuberance. 

Jugal  point  =  a  point  situated  at  the  angle  which  the  posterior  border  of  the 
frontal  process  of  the  malar  forms  with  the  superior  border  of  its  zygomatic 
process. 

Lambda  =  the  meeting  of  the  sagittal  and  lambdoid  sutures. 

Nasion,  or  nasal  point  =  the  meeting  of  the  two  fronto-nasal  sutures. 

Obelion  -  the  point  where  the  horizontal  line  connecting  the  parietal  fora- 
mina intersects  the  sagittal  suture. 

Occipital  points  the  part  of  the  occipital  in  the  median  plane  at  the  greatest 
'.listance  from  the  glabella. 

Ophryon  -  the  centre  of  a  line  drawn  from  one  temporal  ridge  to  the  other 
across  the  narrowest  ])art  of  the  frontal  region. 

Opisthion     tlie  centre  of  tlie  posterior  margin  of  tlic  foramen  magnum. 

10  -  Z 


148  A  MANUAL  OF  ANATOMY 

Pterion  =  the  region  of  the  spheno-parietal  suture. 
Rhinion  =  the  lower  part  of  the  internasal  suture. 

Stephanion  =  the  point  where  the  superior  temporal  ridge  crosses  the  coronal 
suture. 

Subnasal  point  =  the  centre  of  the  base  of  the  anterior  nasal  spine. 

The  horizontal  circumference  of  the  cranium  represents  the  measurement 
at  the  level  of  a  plane  passing  through  the  most  prominent  part  of  the  glabella 
in  front,  the  pterion  laterally,  and  the  occipital  point  behind. 

The  greatest  length  represents  the  measurement  from  the  most  prominent 
part  of  the  glabella  to  the  occipital  point.  The  greatest  breadth  represents 
the  transverse  measurement  at  the  level  of  the  most  prominent  parts  of  the 
temporal  fossae  above  the  supramastoid  crests.  The  proportion  of  greatest 
breadth  to  greatest  length  is  the  index  of  breadth,  or  cephalic  index.  In 
civilized  races  about  7  inches  represents  an  average  length,  and  about  5  i  inches 
an  average  breadth.  According  to  their  cephalic  index,  skulls  are  arranged 
in  three  classes,  namely,  brachycephalic  (broad  and  short),  with  a  cephalic 
index  over  80,  as  in  Malays,  etc. ;  mesaticephalic  (intermediate),  with  an  index 
of  75  to  80,  as  in  Europeans  and  Chinese  ;  and  dolicocephalic  (long  and  narrow), 
with  a  cephalic  index  below  75,  as  in  Kaffirs  and  Fijians. 

The  height  of  the  skull  represents  the  measurement  from  the  basion  to  the 
bregma,  and  its  proportion  to  the  length  is  the  index  of  height,  or  vertical 
index.     Its  average  in  civilized  races  corresponds  with  the  breadth. 

The  longitudinal  arc  of  the  skull  represents  the  measurement  from  the 
nasion  to  the  opisthion  carried  over  the  roof,  and  the  basi-nasal  length  repre- 
sents the  measurement  from  the  basion  to  the  nasion.  These  two  measure- 
ments, plus  the  distance  between  the  basion  and  the  opisthion,  represent 
the  vertical  circumference  of  the  cranium  in  the  median  plane.  The  degree 
of  projection  of  the  jaws  is  ascertained  from  the  gnathic  or  alveolar  index. 
This  index  represents  the  proportion  of  the  basi-alveolar  length  to  the  basi- 
nasal.  According  to  the  gnathic  index,  skulls  are  arranged  in  three  classes, 
namely,  orthognathous  (straight  and  upright  jaw),  with  a  gnathic  index 
below  98,  as  in  Europeans  ;  mesognathous  (intermediate  jaw),  with  an  index 
of  from  98  to  103,  as  in  Chinese  and  Japanese  ;  and  prognathous  (forward 
jaw),  with  an  index  over  103,  as  in  Australians. 

The  form  of  the  anterior  nasal  aperture  is  ascertained  from  the  nasal  index. 
This  represents  the  proportion  of  the  greatest  transverse  measurement  of  the 
aperture  to  the  height,  which  latter  is  the  measurement  from  the  nasion  to 
the  subnasal  point.  According  to  their  nasal  index,  skulls  are  arranged  in 
three  classes,  namely,  leptorhine  (narrow  nose),  with  a  nasal  index  below  48, 
as  in  Europeans  ;  mesorhine  (intermediate  nose),  with  an  index  of  from  48  to 
53,  as  in  Chinese  and  Japanese  ;  and  platyrhine  (broad  nose),  with  an  index 
above  53,  as  in  Australians  and  Kaffirs. 

The  form  of  the  orbital  aperture  is  ascertained  from  the  orbital  index,  which 
represents  the  proportion  of  the  height  to  the  width  of  the  orbital  aperture. 
There  are  three  varieties  of  orbital  index,  namely,  megaseme  (great  index), 
when  it  exceeds  89,  as  in  the  Chinese  ;  mesoseme  (intermediate  index),  when 
it  is  between  89  and  84,  as  in  Europeans  ;  and  microseme  (small  index),  when 
it  is  below  84,  as  in  Australians. 

Deformities  of  the  Skull. 

The  most  common  cause  of  cranial  deformities  is  premature  synostosis  or 
osseous  union  of  bones  which  are  normally  separate,  the  result  being  closure 
or  obliteration  of  certain  sutures.  When  the  sagittal  suture  becomes  prema- 
turely obliterated  transverse  growth  is  arrested,  and,  to  compensate  for  this,  in- 
creased growth  takes  place  at  the  coronal  and  lambdoid  sutures.  The  antero- 
posterior diameter  of  the  cranium  is  greatly  increased,  and  the  vault  assumes 
a  boat-like  shape.  This  variety  is  known  as  scaphocephalus.  When  the 
coronal  suture  becomes  prematurely  obliterated,  increased  growth  takes  place 
upwards,  and  the  vertical  diameter  is  greatly  increased.  This  varietyj'is  known 
as  acrocephalus  (pointed  head).  When  one-half  of  the  coronal  or  lambdoid 
suture  becomes  prematurely  obliterated,  oblique  deformity  takes  place,  this 


THE  BONES  OF  THE  HEAD 


149 


form  being  known  as  plagiocephalus  (oblique  or  awry  head).  When  the 
metopic  or  frontal  suture  becomes  prematurely  obliterated,  gro\vi;h  is  arrested 
in  the  frontal  region,  and  the  skull  assumes  a  triangular  shape.  This  variety 
is  knov\-n  as  trigonocephalus.  When  premature  obliteration  of  the  sutures  at 
the  base  oi  the  skull  takes  place,  the  deformity  known  as  cretin  skull  results. 
This  is  characterized  by  enlargement  of  the  cranium  (except  in  the  occipital 
region),  which  becomes  very  heavy,  and  assumes  an  irregular,  somewhat 
conical  shape,  with  the  apex  at  the  sagittal  suture.  It  is  associated  with 
mental  dulness,  idiocy,  and  stunted  growth,  and  the  general  condition  is 
known  as  cretinism. 

Development  of  the  Skull. 
Development  of  the  Cranium. — The  notochord  (see  p.  53)  extends  beyond 
the  region  of  the  future  vertebral  column  into  the  base  of  the  skull,  where  it 
reaches  as  far  forwards  as  the  under  aspect  of  the  anterior  end  of  the  mid- 
brain. In  the  skull,  as  elsewhere,  it  is  invested  by  mesoblast,  which  expands 
and  forms  a  membranous  capsule  for  the  cerebral  vesicles.     This  capsule 


Fig.  87. — Diagrams  of  the  Primitive  Cartilaginous  Cranium 
(Wiedersheim). 

A.  First  Stage. — N,  Notochord;  PchC,  Parachordal  Cartilage;  Tr,  Prechordal 

Cartilage;  PPS,  Primitive  Pituitary  Space;  Olf,  Opt,  Aud,  positions  of 
Organs  of  Smell,  Sight,  and  Hearing. 

B.  Second  Stage. — N,  Notochord ;  PchR,  Parachordal  Region  (Basilar  Plate) ; 

TrR,   Fusion  of  Prechordal  Cartilages;   PPS,  Primitive  Pituitary  Space; 
TrR,  Prechordal  Region;  Olf,  Opt,  Aud,  as  in  A. 

represents  the  primitive  membranous  skull.     Its  basal  part  undergoes  chon- 
drification,  whilst  the  remainder  retains  its  membranous  character. 

The  cartilage  appears  in  the  form  of  two  pairs  of  rods,  posterior  and 
anterior.  The  posterior  pair  lie  on  either  side  of  the  notochord,  and  are  called 
the  parachordal  cartilages.  The  anterior  pair  lie  on  cither  side  of  the  '  primi- 
tive pituitary  space,'  and  are  called  the  prechordal  cartilages.  The  para 
chordals  unite  to  form  a  basilar  plate,  which  ultimately  invests  the  notochord 
on  its  dorsal  and  ventral  aspects.  Posteriorly  the  prechordals  join  the  para- 
chordals, whilst  anteriorly  they  become  fused  in  front  of  the  primitive  pituitary 
space.  These  changes  give  rise  to  one  continuous  basal  cartilage,  which  is 
divisible  into  two  regions — ]>arachordal,  posterior  in  position,  and  prechordal, 
situated  anteriorly.  The  parachordal  region  gives  rise  to  (i)  the  occipital 
bone,  except  its  interparietal  portion,  and  (2)  the  dorsum  sellcne.  posterior 
part  of  the  sella  turcica,  great  wmg,  and  external  pterygoid   plate,  of  the 


I50 


A   MANUAL  OF  ANATOMY 


sphenoid.  The  prechordal  region  posteriorly  gives  rise  to  the  anterior  part  of 
the  sella  turcica,  and,  in  front  of  this,  it  resolves  itself  into  presphenoid  and 
ethmoidal  portions.  The  presphenoid  portion  gives  rise  to  the  presphenoid 
division  of  the  sphenoid,  and  the  ethmoidal  portion  is  concerned  in  the  develop 
ment  of  the  ethmoid  and  face. 

External  to  each  parachordal  cartilage  is  the  membranous  periotic  capsule, 
which  becomes  invested  by  cartilage,  and  these  periotic  cartilaginous  capsixles 
become  connected  with  the  parachordal  plate.  It  is  in  this  periotic  car- 
tilaginous capsule,  at  each  side,  that  the  centres  of  ossification  for  the  petro- 
mastoid  or  periotic  portion  of  the  temporal  appear.  Anteriorly  the  periotic 
capsule  of  either  side  is  separated  from  the  cartilage  of  the  great  wing  of  the 
sphenoid  by  a  membranous  interval,  and  it  is  in  this  membrane  that  the 
squamous  portion  of  the  temporal  is  formed.  The  interparietal  portion  of 
the  occipital,  the  parietals,  and  the  frontal  are  developed  in  that  part  of  the 


B  ip  n  pr 


mn  pr        ^y^ 


n  pr 


Fig.  88. — Head  of  an  Embryo  (His). 

A,  View  from  above. — B.  View  showing  roof  of  mouth  after  removal  of  the 
Mandible,  fn-pr,  Fronto-Nasal  Process;  mnpr,  Mesial  Nasal  Process, 
terminating  in  Globular  Process  ;  Inpr,  Lateral  Nasal  Process  ; 
mx.  Maxillary  Process;  imi,  Mandibular  Arch;  hy,  Hyoid  Arch.  The 
X  in  B  indicates  the  Nasal  Lamina. 


membranous  cerebral  capsule  which  does  not  undergo  chondrification.  From 
the  foregoing  summary  of  the  development  of  the  cranium  it  will  be  observed 
that  it  is  composed  of  basal  or  cartilage  bones  formed  in  the  chondro-cranium, 
and  of  tegmental  or  membrane  bones  formed  in  the  membranous  cranium. 

Development  of  the  Face. — The  bones  of  the  face  are  developed  from  the 
fronto-nasal  process,  the  two  mandibular  arches,  and  the  two  maxillary 
processes.  The  fronto-nasal  process  springs  from  the  primitive  cerebral 
capsule,  and  it  contains  a  core  derived  from  the  ethmoidal  division  of  the 
prechordal  region.  It  consists  of  a  central  part  and  two  symmetrical  halves. 
Each  half  presents  two  processes,  called  mesial  or  internal,  and  lateral  or 
external,  nasal  processes.  The  mesial  nasal  process,  of  each  side,  terminates 
interiorly  in  an  enlargement,  which  is  known  as  the  globular  process.  From 
each  globular  process  a  plate  of  cartilage  grows  backwards,  these  two  plates 
being  termed  the  nasal  lamincB.  They  are  at  first  separate,  but  they  soon 
unite  and  form  the  greater  part  of  the  nasal  septum.  The  septal  cartilage 
gives  rise  to  the  perpendicular  plate  of  the  ethmoid,  and  the  vomer  is  de- 


THE  TEETH  151 

veloped  in  the  membrane  which  covers  that  cartilage.  The  globular  pro- 
cesses, like  the  nasal  laminae,  are  at  first  separate,  but  they  soon  unite.  The 
depressed  portion  at  the  place  of  their  fusion  gives  rise  to  the  lower  part  of 
the  nasal  septum  and  the  columella  nasi.  Each  globular  process  forms  the 
premaxillarj'  part  of  the  superior  maxilla  and  the  mesial  portion  of  the  upper 
lip.  The  lateral  nasal  process  lies  above  the  ventral  part  of  the  maxillary 
process,  from  which  it  is  separated  b}-  the  lachrymal  sulcus.  It  has  the  nasal 
pit  internal  to  it,  and  the  ocular  depression  on  its  outer  side.  The  lachrymal 
sulcus  disappears  as  the  lateral  nasal  process  joins  the  maxillary  process. 
but  it  indicates  the  deep  position  of  the  future  lachrj'-mal  sac  and  nasal  duct. 
The  cartilage  of  the  lateral  nasal  process  gives  rise  to  the  lateral  mass,  and 
half  of  the  cribriform  plate,  of  the  ethmoid,  and  the  inferior  turbinate  bone; 
and  the  membrane  which  covers  the  cartilage  gives  rise  to  the  nasal  process 
of  the  superior  maxilla,  and  the  nasal  and  lachr\'mal  bones. 

Each  mandibular  arch  contains  a  bar  of  cartilage,  which  is  known  as  Meckel's 
cartilage.  The  upper  end  of  this  cartilage  is  connected  with  the  periotic 
capsule,  and  the  lower  end  meets  its  fellow.  The  upper  end  persists  as  the 
malleus  and  the  incus,  and  the  lower  end  gives  rise  to  the  incisor  portion 
of  the  body  of  the  mandible.  The  intervening  portion  of  Meckel's  cartilage 
disappears.  The  fibrous  tissue  which  surrounds  the  lower  part  of  this 
portion  forms  a  large  part  of  the  mandible,  whilst  that  which  surrounds  the 
upper  part  persists  as  the  spheno-mandibular  ligament. 

Each  maxillary  process  i.5  an  outgrowth  from  the  dorsal  end  of  the  man- 
dibular arch  of  its  own  side.  It  grows  in  a  forward  direction  between  the  eye 
and  the  mouth,  and  abuts  against  the  lateral  nasal  process,  with  which  it 
blends.  Under  normal  circumstances  it  also  unites  with  the  globular  process. 
which  belongs  to  the  mesial  nasal  process.  The  maxillan,'  process  gives  rise 
to  the  chief  part  of  the  superior  maxilla,  and  to  the  malar  bone.  The  process 
contains  a  small  piece  of  cartilage,  called  the  pterygo-palafine  bar,  and  the 
membrane  which  invests  this  bar  gives  origin  to  the  palate  bone  and  the  internal 
ptent'gnid  plate  of  the  sphenoid.     The  cartilaginous  bar  itself  soon  disappears. 

Development  of  the  Hyoid  Bone, — This  bone  is  developed  from  the  cartila- 
ginous bars  of  the  second  visceral  or  hyoid,  and  third  visceral  or  thyro-hyoid, 
arches,  of  either  side.  The  hyoid  bars  are  continuous  with  one  another  at 
the  median  line  through  the  copula,  which  gives  rise  to  the  body  of  the  hyoid 
bone.  The  small  corniia  are  developed  from  the  ventral  ends  of  the  hyoid 
bars.  The  upper  end  of  each  gives  rise  to  the  styloid  process  of  the  temporal 
bone,  and  the  intermediate  part  disappears,  but  its  fibrous  investment  persists 
as  the  stylo -hyoid  ligament.  The  thyro-hyoid  bar  of  each  side  gives  rise  at 
its  ventral  end,  which  is  connected  with  the  copula,  to  the  great  cornn  of  the 
hyoid  bone,  whilst  the  remainder  of  the  bar  disappears. 

THE  TEETH. 

The  teeth  are  divided  into  two  sets,  namely,  the  temporary, 
milk,  or  deciduous,  which  belong  to  early  infancy,  and  the  permanent, 
which  replace  the  temporary.  The  temporary  teeth  are  twenty  in 
number — ten  upper,  five  in  each  superior  maxilla,  and  ten  lower, 
five  in  each  half  of  the  inferior  maxilla.  The  number  of  permanent 
teeth  is  thirty-two — sixteen  upper,  and  sixteen  lower. 

The  Permanent  Teeth. — Proceeding  from  the  median  line  in  a 
direction  outwards  and  backwards,  the  permanent  teeth  are  as 
follows:  central  incisor,  lateral  incisor,  canine,  first  bicuspid, 
second  biscupid,  and  first,  second,  and  third  molars.  The  third 
molar  is  known  as  the  dens  sapicnticB  or  wisdom  tooth.  Each 
tooth  is  composed  of  the  following  parts:  the  crown,  which  is 
the  part  above  the  gum;   the  root,  which  is  the  part  embedded 


15- 


A  MANUAL  OF  ANATOMY 


Upper 


Lower 


Incisors 


Upper 


Canines 


Lower 


Upper 


Bicuspids 


Lower 


Upper 


Lower 


Fig. 


89. — The  Permanent  Teeth 
OF  THE  Left  Side. 


in  the  alveolus;  and  the  neck, 
which  lies  between  the  crown  and 
root.  The  surface  of  a  tooth 
which  looks  towards  the  lip  is 
called  labial,  and  that  looking 
towards  the  tongue  lingual,whilst 
of  the  opposed  surfaces  one  is 
called  mesial  or  proximal,  and 
the  other  lateral  or  distal. 

The  Incisors. — The  crowns  of 
the  incisor  teeth  are  chisel- 
shaped,  the  cutting  edge  of  the 
upper  being  bevelled  behind,  and 
that  of  the  lower  in  front. 

The  upper  central  incisor  is 
larger  than  the  lateral,  and 
gradually  tapers  from  the  crown 
to  the  root.  The  length  of  the 
crown  exceeds  its  breadth.  The 
labial  surface  is  convex,  whilst 
the  lingual  is  concave,  and  pre- 
sents near  the  gum  a  prominence, 
called  the  basal  ridge  or  cingidum 
(girdle).  The  root  is  long,  taper- 
ing, conical,  and  flattened  on 
either  side.  The  upper  lateral  in- 
case r  is  smaller  than  the  central, 
which  it  for  the  most  part 
resembles,  the  cingulum  being 
more  prominent. 

The  lower  central  incisor  is 
smaller  than  the  lateral,  and 
narrower  than  the  upper  central 
incisor,  and  the  root  is  much 
flattened  laterally.  The  lower 
lateral  incisor  is  larger  than  the 
central,  which  it  for  the  most 
part  resembles,  but  its  root  is 
longer,  and  on  each  flattened 
lateral  surface  there  may  be 
an  indication  of  a  longitudinal 
groove. 

The  Canines.— The  crown  of  a 
Molars  canine  tooth  is  larger  than  that 
of  an  incisor.  .  It  is  conical,  and 
terminates  in  a  blunt  cusp,  from 
which  it  is  known  as  the  cuspidate 
tooth.  The  labial  surface  is 
convex,  and  the  lingual  concave. 
In  each  upper  canine  the  lingual 
surface  presents  a  median  ridge, 


THE  TEETH  IS3 

which  extends  from  the  cusp  to  the  cingulum.  The  root  is  long, 
thick,  much  compressed  laterally,  and  marked  on  either  side  by 
a  distinct  longitudinal  groove.  The  lower  canines  have  no  median 
ridge  on  the  lingual  surface,  the  cingulum  is  absent,  and  the  root 
is  shorter  than  in  the  upper. 

The  Bicuspids. — The  bicuspids  or  premolars  are  smaller  than  the 
canines.  The  crown  is  quadrilateral,  and  its  labial  border  is 
longer  than  the  lingual .  It  is  provided  with  two  cusps,  of  which  the 
labial  is  the  larger  and  broader,  and  these  are  separated  by  a  deep 
transverse  fissure.  The  labial  and  lingual  surfaces  are  convex,  and 
there  is  no  cingulum.  The  root  is  single,  and  is  much  flattened 
laterally.  It  usually  presents  on  either  side  a  longitudinal  groove, 
which  in  many  cases  is  so  deep  as  to  separate  it  into  two  fangs 
over  the  greater  part  of  its  length.  The  upper  second  bicuspid  has 
its  cusps  nearly  equal,  and  its  root,  if  single,  is  more  deeply  grooved 
laterally  than  that  of  the  first. 

The  lower  bicuspids  are  smaller  than  the  upper.  The  lingual 
cusp  is  smaU  and  narrow,  a  circumstance  which  renders  the  crown 
triangular,  as  seen  from  above.  The  cusps  are  connected  by 
a  ridge.  The  root  is  single,  rounded,  and  tapering.  The  lower 
second  bicuspid  differs  from  the  first  in  having  a  larger  crown,  of 
somewhat  quadrilateral  outline.  The  lingual  cusp  is  more  developed, 
and  the  crown  approaches  the  molar  type.  The  upper  first  bicuspid 
is  the  most  predisposed  of  this  group  to  have  its  root  divided  into 
two  fangs. 

The  Molars. — The  upper  molar  teeth  have  quadrate  crowns  with 
rounded  angles.  In  the  case  of  the  first  and  second,  the  grinding 
surface  is  furnished  with  four  cusps,  situated  at  each  angle  of  the 
square,  two  of  them  being  labial  and  two  lingual.  The  anterior 
lingual  cusji  is  the  largest,  and  it  is  connected  with  the  posterior 
labial  cusp  by  an  oblique  ridge.  The  root  of  each  of  the  first  and 
second  molars  has  three  fangs — two  labial,  and  one  ]:)alatal.  The 
latter  is  the  largest  and  most  divergent,  its  direction  being  inwards 
towards  the  palate.  The  third  u})per  molar  is  subject  to  much 
variety,  and  is  usually  of  small  size.  The  grinding  surface  of  the 
crown  is  somewhat  quadrate.  The  two  lingual  cusps  are  frequently 
confluent,  and  the  fangs  of  the  root  are  blended  into  one  tapering 
cone. 

The  first  lower  molar  is  the  largest.  The  crown  is  quadrate,  and  its 
grinding  surface  is  provided  with  five  cusps,  four  of  which  are  placed 
at  the  angles  of  the  square,  being  separated  by  a  crucial  fissure. 
The  fifth  cusp  is  situated  at  the  posterior  part  of  the  crucial  fissure, 
where  it  lies  between  the  two  distal  cusps.  The  root  has  two  fangs, 
anterior  and  posterior,  both  of  which  are  much  com})ressed  from 
before  backwards.  Each  fang  is  usually  grooved  along  its  centre, 
sometimes  to  such  an  extent  as  to  give  rise  to  four  fangs.  The 
second  lower  molar  bears  a  general  resemblance  to  the  first.  The 
fifth  cusp,  if  jjresent,  is  not  so  well  marked,  and  it  is  regarded  as 
being  ];resent  in  about  24  per  cent,  of  cases.  The  two  fangs  of  the 
root  arc  frequently  blended.  The  third  lower  molar  is  of  larger 
size  than  the  corresponding  ujjijcr  tooth.     Its  crown  has  usually  five 


154 


A   MANUAL  OF  ANATOMY 


cusps,  and  its  root  has  two  fangs,  which  may  be  separate,  or  con- 
fluent.  In  the  latter  case  a  groove  indicates  the  two-fanged  condition. 

The  Temporary  Teeth.— Proceeding  from  the  median  line,  these 
are  as  fohows  on  either  side  :  two  incisors,  central  and  lateral,  one 
canine,  and  two  molars,  first  and  second.  Their  necks  are  more 
constricted  than  in  the  permanent  set.  The  incisors  and  canines 
resemble,  for  the  most  part,  those  of  the  permanent  set,  but  they 
are  smaller.  The  molars,  which  are  replaced  by  the  permanent 
bicuspids,  exceed  them  in  size,  the  second  molars  being  particularly 
large.  The  first  upper  molar  has  three  cusps — two  labial  and  one 
lingual,  the  second  upper  and  first  lower  molars  have  each  four, 
and  the  second  lower  molar  has  five. 

Eruption  of  the  Teeth. — The  eruption  of  particular  teeth  of  the 
lower  jaw  precedes  that  of  the  corresponding  teeth  of  the  upper 
jaw,  and  the  periods  are  as  follows  : 


Temporary  Teeth. 


Incisors 

First  Molars 
Canines 
Second  molars 


6th  to  1 2th  month 
1 2th  to  14th 
14th  to  20th 
20th  to  24th       ,, 


Fig.  90. — The  Superior  and  Inferior  Maxillary  Bones  at  the  Seventh 
Year,  showing  most  of  the  Temporary  Teeth,  and  the  Permanent 
Teeth  about  to  replace  them. 

The  First  Permanent  Molars  and  the  Permanent  Lower  Central  Incisors 
are  in  position. 


Permanent  Teeth. 


First  molars      .  . 

6th 

year 

Central  incisors             . . 

7th 

Lateral  incisors 

8th 

First  bicuspids 

9th 

Second  bicuspids 

. .      loth 

Canines 

.  .      1 1 th 

Second  molars 

.  .      i2th 

Third  molars   .  . 

.  .      17th 

to 

25th  year 

About  the  sixth  year  is  the  period  at  which  most  teeth  are  present 
in  the  jaws,  there  being  the  twenty  temporary  teeth,  and  all  the 


THE  TEETH 


155 


permanent,  except  the  four  wisdom  teeth,  (namely,  twenty-eight), 
making  in  all  forty-eight. 

Structure  of  a  Tooth. — The  crown  of  a  tooth  contains  a  central 
cavity,  called  the  pulp  cavity,  which  is  occupied  by  the  dental  pulp. 
The  shape  of  the  pulp  cavity  corresponds  with  that  of  the  crown, 
and  it  extends  into  the  root,  and  as  many  fangs  as  compose  it, 
terminating  in  a  small  opening  on  the  apex  of  the  fang.  The 
cavity  also  extends  for  a  little  into  the  cusps  of  the  bicuspids  and 
molars,  and  in  the  incisors  it  is  continued  into  each  angle  of  the 
crown.  The  wall  of  the  cavity  presents  a  number  of  openings, 
which  lead  into  the  dentinal  tubules.  The  dental  pulp  is  composed 
of  a  matrix  of  connective  tissue,  containing  bloodvessels,  nerves, 

B 


^Enamel  on  Crown 


Vc   -Dentine 


Dentine 
Pulp  Cavity 


Prolongation  of  Pulp  Cavity 
into  Fangs 


Opening  on  Apex  of  Fang 

Fig.  91. — Sections  of  Teeth. 
A,  Lower  Molar ;    B,   Lower  Incisor. 


--  Pulp  Cavity 

—  Dentine 
Crusta  Petrosa 


cells,  and  fibres,  which  latter  seem  to  be  processes  of  the  cells.  It 
is  destitute  of  lymphatics.  The  cells  are  scattered  throughout  the 
matrix,  and  at  the  surface  of  the  pulp  they  form  a  continuous 
layer,  being  there  known  as  the  odontoblasts.  This  layer  is  some- 
times spoken  of  as  the  memhrana  eboris.  The  pulp  is  very  vascular 
and  sensitive,  its  vessels  and  nerves  reaching  it  through  the  minute 
openings  at  the  apices  of  the  fangs. 

The  substance  of  the  tooth  is  formed  of  three  tissues,  namely, 
ivory  or  dentine,  enamel,  and  cement  or  crusta  petrosa.  The 
dentine  forms  the  princij)al  part  of  the  tooth,  surrounding  the  ])ulp 
cavity  and  its  prolongations  ;  the  enamel  covers  the  exposed  jjart 
or  crown  ;  and  the  cement  covers  the  root. 


156 


A  MANUAL  OF  ANATOMY 


Dentine. — ^This  bears  a  resemblance  to  bone,  but  contains  rather 
less  animal,  and  more  earthy,  matter,  the  proportion  in  loo  parts 
being  about  28  of  animal  matter  to  72  of  earthy.  The  dentine 
has  a  striated  appearance,  due  to  the  fact  that  it  is  traversed  by 
a  number  of  minute  branched  channels,  called  the  dentinal  tubules, 
which  radiate  in  a  curved  manner  outwards  from  the  pulp  cavity 
to  the  deep  aspect  of  the  enamel  and  cement.  These  tubules 
contain  processes  of  the  odontoblasts  which  form  the  membrana 
eboris,  and  are  known  as  Tomes'  fibres.  The  part  of  the  dentine 
adjacent  to  the  enamel  and  cement  is  known  as  the  granular  layer 


Fig.  92. 


-Section  of  the  Fang  of 
A  Tooth. 


I,  Cement  ;    2,  Granular  Layer  of 
Purkinje  ;  3,  Dentinal  Tubules. 


Fig.  93. — Enamel  Prisms. 

A,  Four  prisms  (Longitudinal  View) ; 
B,  Surface  of  the  Enamel. 


of  Purkinje.  It  presents  a  number  of  irregular  spaces,  known  as 
the  interglobular  spaces,  which  are  surrounded  by  minute  globules 
of  calcareous  matter. 

Enamel. — This  caps  and  protects  the  dentine  of  the  crown.  It 
is  exceedingly  hard,  which  is  due  to  the  fact  that  it  contains  no 
animal  matter — at  least,  to  any  appreciable  extent.  It  consists 
of  solid  hexagonal  prisms,  which  are  marked  by  transverse  stria- 
tions.  These  are  received  by  their  deep  extremities  into  depres- 
sions on  the  dentine,  and  are  placed  vertically  on  the  summit  of 
the  crown,  but  horizontally  on  its  sides.     At  the  period  of  eruption 


THE  TEETH  157 

of  a  tooth,  and  for  some  little  time  thereafter,  the  enamel  of  the 
crown  is  covered  by  a  thin  membrane,  called  the  enamel  cuticle 
or  Nasmyth's  membrane. 

Cement  or  Crusta  Petrosa. — This  covers  the  dentine  which  forms 
the  root  of  the  tooth.  It  is  true  bone,  and  contains  lacunae  and 
canaliculi,  but  it  is  destitute  of  Haversian  canals. 

The  root  of  a  tooth  is  maintained  in  its  alveolus  by  the  peri- 
dental membrane  or  dental  periosteum,  which  covers  the  cement, 
and  lines  the  wall  of  the  alveolus,  being  continuous  with  the  gum  at 
the  neck  of  the  tooth.     The  articulation  is  called  gomphosis. 

Development  of  the  Teeth. 

The  development  of  the  milk  teeth  commences,  about  the  sixth  week  of 
intra-uterine  life,  in  a  thickening  of  the  deep  layer  of  the  stratified  buccal 
epithelium  along  the  course  of  the  forming  jaw.  This  epiblastic  thickening  is 
called  the  common  enamel  or  dental  germ,  and  it  is  received  into  a  groove 
formed  by  the  mesoblastic  tissue  of  the  forming  jaw.  A  further  development 
of  the  common  enamel  germ  takes  place  in  the  form  of  special  cell  groups, 
known  as  the  special  enamel  germs.  A  vascular  dental  papilla,  in  form  like 
the  crown  of  the  future  tooth,  then  grows  from  the  mesoblast  into  the  special 
enamel  germ.  The  papilla  is  composed  of  a  reticulum  of  cells,  the  outermost 
of  which  are  called  odontoblasts.  Each  special  enamel  germ,  with  its  con- 
tained dental  papilla,  becomes  separated  from  the  buccal  epithelium,  and 
surrounded  by  an  investment,  called  the  dental  sac,  which  is  derived  from  the 
mucosa.  The  odontoblasts  of  the  dental  papilla  give  rise  to  the  dentine,  and 
the  cellular  reticulum  of  the  papilla  forms  the  tooth  pulp.  The  dentine  is  laid 
down  in  successive  layers,  and,  as  the  odontoblasts  become  shifted  inwards, 
they  leave  behind  them  processes,  which  become  invested  by  calcareous  matter, 
and  so  the  dentinal  tubules  are  formed  with  processes  of  the  odontoblasts 
within  them.  The  portion  of  the  special  enamel  germ  which  covers  the  dental 
papilla  is  known  as  the  enamel  organ,  and  it  is  composed  of  four  parts,  as 
follows:  (i)  a  layer  of  columnar  cells  in  direct  contact  with  the  dentine, 
called  the  adamantoblasts  or  enamel  cells,  which  give  rise  to  the  enamel 
prisms  by  depositing  matter  ultimately  becoming  calcified  ;  (2)  the  stratum 
intermedium,  composed  of  two  or  three  layers  of  polyhedral  cells  ;  (3)  a 
reticulum  of  stellate  cells  ;  and  (4)  an  outer  layer  of  cubical  epithelium.  The 
enamel,  like  the  dentine,  is  laid  down  in  layers,  the  adamantoblasts  gradually 
shifting  their  position  outwards.  During  this  process  the  other  layers  of 
the  enamel  organ  are  gradually  disappearing,  being  wholly  lost  when  the 
eruption  of  the  tooth  takes  place.  The  last  layer  of  matter  deposited  by  the 
adamantoblasts  does  not  undergo  calcification,  but  forms  the  membrane, 
called  the  enamel  cuticle  or  Nasmyth's  membrane,  which  covers  the  crown 
of  the  tooth  for  some  little  time  after  its  eruption. 

The  cement  is  developed  from  the  inner  part  of  the  dental  sac,  which 
resembles  the  osteogenetic  layer  of  periosteum,  wliilst  the  outer  part  of  the 
dental  sac  gives  rise  to  the  dental  periosteum. 

Those  permanent  teeth  which  replace  the  temporary  teeth,  namely, 
incisors,  canines,  and  bicuspids,  are  developed  from  enamel  germs  which  are 
outgrowths  from  those  of  the  temporary  teeth.  Each  of  these  becomes 
provided  with  a  papilla,  and  the  various  stages  of  development  are  as  in  the 
temporary  teeth. 

The  twelve  permanent  molar  teeth,  six  upper  and  six  lower,  do  not  take  the 
place  of  any  temporary  teeth,  and  tlierefore  arise  in  a  different  manner.  They 
are  developed  from  gi  backward  extension  of  the  original  common  enamel  germ, 
and  the  formation  from  this  of  special  enamel  germs  at  somewliat  long  intervals. 
Thereafter  the  process  of  development  proceeds  as  in  the  temjiorary  teeth. 

When  tlie  permanent  teeth  are  fully  formed  the  roots  of  the  temporary 
teeth  are  absorbed  by  the  osteoclasts  of  tlie  dental  periosteum,  and,  as  they 
drop  out,  the  permanent  teeth  take  their  place. 


i5« 


A  MANUAL  OF  ANATOMY 


III.  THE  BONES  OF  THE  UPPER  LIMB. 

The  upper  limb  is  arranged  in  four  divisions,  namely,  the  pectoral 
or  shoulder-girdle,  brachium  or  arm  proper,  antibrachium  or  fore- 
arm, and  manus  or  hand.  The  shoulder-girdle  consists  of  the 
clavicle  and  scapula,  the  brachium  comprises  the  humerus,  the 
antibrachium  is  composed  of  the  radius  and  ulna,  and  the  hand 
is  subdivided  into  a  carpus,  comprising  eight  bones,  a  metacarpus, 
consisting  of  five  bones,  and  phalanges,  which  number  fourteen. 


The  Clavicle. 

The  clavicle  or  collar-bone  is  situated  at  the  lower  part  of  the 
neck  anteriorly,  where  it  lies  above  the  first  rib,  and  it  extends 
outwards  and  backwards  from  the  upper  border  of  the  presternum 
to  the  acromion  process  of  the  scapula.  The  bone  presents  two 
curves,   an  inner  or  sternal,   occupying  two- thirds,  with  its  con- 


Pectoralis  Major 


Acromial  Facet 


Sternal  I 

Extremity      Sterrio-cleido-mastoid 


Conoid 
Tubercle 


Trapezius 

Fig.  94. — The  Right  Clavicle  (Superior  View). 

vexity  directed  forwards,  and  an  outer  or  acromial,  extending  over 
the  outer  third,  with  its  convexity  directed  backwards.  These 
curves  impart  elasticity  to  the  bone.  The  clavicle  is  divided  into 
a  shaft  and  two  articular  extremities. 

The  shaft  is  somewhat  quadrilateral  over  its  inner  two-thirds, 
and  compressed  from  above  downwards  over  its  outer  third.  The 
superior  surface  is  for  the  most  part  narrow,  but  externally  it  becomes 
broad.  At  its  inner  end,  near  the  postero-superior  border,  it  pre- 
sents a  rough  ridge,  about  i|  inches  long,  for  the  origin  of  the 
clavicular  head  of  the  sterno-cleido-mastoid.  At  its  outer  ex- 
panded part  it.  is  encroached  upon  by  the  tendinous  fibres  of  the 
trapezius  and  deltoid.  Elsewhere  it  is  covered  by  the  skin,  fascia, 
and  platysma  myoides.  The  anterior  sit-rface  is  convex  over  its 
inner  two-thirds,  and  concave  over  its  outer  third,  where  it  is 
reduced  to  a  mere  rough  border.  Over  the  inner  half  it  is  rough 
for  the  origin  of  the  clavicular  portion  of  the  pectoralis  major,  and 
over  its  outer  marginal  third  it  gives  origin  to  the  clavicular  portion 
of  the  deltoid.  At  the  inner  end  of  the  deltoid  impression  there 
is  sometimes  a  pointed  projection,  known  as  the  deltoid  spine.   The 


THE  BONES  OF  THE  UPPER  LIMB 


159 


posterior  surface  is  concave  over  its  inner  two-thirds,  and  convex 
over  its  outer  third,  where  it  is  narrowed  into  a  rough  border.  The 
inner  two- thirds  overhang  the  subclavian  vessels  and  trunks  of 
the  brachial  plexus,  whilst  the  outer  marginal  third  gives  insertion 
to  the  upper  fibres  of  the  trapezius.  At  the  inner  end  of  the  im- 
pression for  these  fibres,  opposite  the  deltoid  spine,  there  is  a 
conical  projection  which  extends  on  to  the  inferior  surface  for  a 
little,  called  the  conoid  tubercle,  for  the  conoid  ligament.  About 
the  centre  of  the  posterior  surface  there  is  the  medullary  foramen 
for  the  m.edullary  artery,  which  is  a  branch  of  the  suprascapular. 
The  canal  to  v.'hich  the  foramen  leads  is  directed  outwards.  The 
foramen  may  be  situated  on  the  inferior  surface  in,  or  close  to,  the 
subclavian  groove,  or  there  may  be  two  foramina,  one  on  the 
posterior  and  one  on   the  inferior  surface,  about  an  inch  apart. 


Rhomboid 


Trapezoid 
Ridge 


Sternal 
Articular  Surface 

Fig.  95. — The  Right  Clavicle. 
A.   Inferior  View  ;  B.   Sternal  Extremity. 

Close  to  the  sternal  end  the  posterior  surface  gives  partial  origin 
to  the  sterno-hyoid.  The  inferior  surface  presents  near  its  sternal 
end  the  rhomboid  imprenssion,  about  an  inch  long,  for  the  costo- 
clavicular or  rhomboid  ligament.  External  to  this  there  is  the 
subclavian  groove,  which  extends  from  the  rhomboid  impression  t© 
near  the  conoid  tubercle,  and  gives  insertion  to  the  subclavius. 
The  groove  is  bounded  by  two  lips,  anterior  and  posterior,  to  which 
the  costo-coracoid  membrane  is  attached  in  two  laminae.  At  the 
outer  extremity  of  the  inferior  surface  there  is  a  rough  oblique  line. 
called  the  trapezoid  ridge,  which  extends  forwards  aT^d  outwards 
from  the  conoid  tubercle,  and  gives  attachment  to  the  trapezoid 
ligament.  The  conoid  tubercle  is  more  fully  seen  here  than  on  the 
posterior  border,  and  is  situated  at  the  pcstero-internal  extremity 
of  the  trapezoid  ridge. 

The  borders  of  the  clavicle  over  its  outer  third  are  anterior  and 
posterior.     The  anterior  border  bifurcates,  over  the  inner  two-thirds, 


i6o  A   MANUAL  OF  ANATOMY 

into  an  antero-superior  and  antero-infefiof  border,  which  enclose 
between  them  the  anterior  surface.  The  -posterior  border  bifurcates, 
over  the  inner  two-thirds,  into  a  postero-superior  and  postero- 
inferior  border,  the  latter  forming  the  posterior  lip  of  the  sub- 
clavian groove.  The  antero-superior  and  postero-superior  borders 
limit  the  superior  surface,  the  postero-superior  and  postero-inferior 
limit  the  posterior  surface,  the  postero-inferior  and  antero-inferior 
limit  the  inferior  surface,  and,  as  stated,  the  antero-inferior  and 
antero-superior  limit  the  anterior  surface. 

The  sternal  extremity  is  enlarged  and  covered  by  cartilage.  As 
viewed  on  end,  it  is  somewhat  triangular,  and  presents  a  prominent 
posterior  angle  which  is  directed  downwards,  inwards,  and  back- 
wards. The  surface  is  concave  from  before  backwards,  and  convex 
from  above  downwards,  and  it  articulates  with  the  clavicular 
impression  on  the  upper  border  of  the  presternum,  an  inarticular 
fibro-cartilage  intervening.  The  circumference  of  the  sternal  end 
is  rough  for  the  sterno-clavicular  and  interclavicular  ligaments, 
except  inferiorly,  where  there  is  a  narrow  strip  for  the  first  costal 
cartilage. 

The  acromial  extremity  presents  an  oval  facet  for  the  acromion 
process  of  the  scapula. 

The  clavicle  receives  its  blood-supply  from  the  suprascapular 
artery  and  the  thoracic  axis. 

Articulations. — Internally  with  the  presternum  and  first  costal 
cartilage,  and  externally  with  the  acromion  process  of  the  scapula. 

Structure. — The  exterior  is  composed  of  compact  bone  which'  is 
thickest  towards  the  centre,  and  the  interior  of  'coarse  cancellated 
tissue,  the  principal  lamellae  being  disposed  longitudinally.  The 
clavicle  has  no  medullary  canal,  but,  towards  the  centre  of  the 
shaft,  the  medullary  spaces  of  the  cancellated  tissue  are  of  large  size. 

Varieties, — (i)  There  may  be  a  deltoid  spine.  (2)  Tlie  superior  surface 
may  present  a  small  slit-Hke  aperture,  variously  situated,  for  one  of  the 
descending  branches  of  the  cervical  plexus  of  nerves. 

The  Clavicle  of  the  Female. — The  bone  is  smoother,  more  slender, 
straighter,  and  more  cylindrical  over  its  inner  two-thirds,  than  that 
of  the  male. 

Ossification. — ^The  clavicle,  which  is  the  earliest  bone  to   ossify,  has  two 
primary  centres  and  one  secondary  centre.     It  is  preceded  by  a  rod  of  con- 
Appears  in  the  i8th  year, 
and  joins  about  25 


Appears  in  the  6th  week 
(intra-uterine) 

Fig.  96. — Ossification  of  the  Clavicle. 

nective  tissue.  "Within  the  two  halves  of  this  rod  collections  of  '  precartila- 
ginous  tissue  '  are  formed,  and  within  these  at  their  contiguous  ends  the 
primary  centres  appear  about  the  6th  week.      Subsequently  the  precartilag- 


THE  BONES  OF  THE  UPPER  LIMB  i6i 

inous  collections  fuse,  and  thereafter  the  primary  centres  coalesce  Ossifi- 
cation from  these  two  centres  proceeds  at  first  in  the  precartilaginous  tissue, 
but  subsequently  in  the  cartilage  to  which  this  tissue  gives  place.  The 
primary  centres  maj'  fail  to  join,  with  the  result  that  the  clavicle  may  persist 
in  tAvo  halves. 

The  secondary  centre  appears  in  the  cartilage  of  the  sternal  end  about  the 
zoth  year,  and  this  epiphysis  joins  the  shaft  about  the  2i,th  year  (Mall  and 
Fawcett). 

The  law  of  ossification  applicable  to  bones  having  a  shaft  and 
one  epiphj'Sis  is  as  follows:  the  medullary  foramen  and  the  canal 
to  which  it  leads  are  directed  towards  that  extremity  ivhich  has  no  epi- 
physis. This  law  is  illustrated  in  the  clavicle  and  the  metacarpal, 
metatarsal,  and  phalangeal  bones. 

The  Scapula. 

The  scapula  or  shoulder-blade  is  situated  on  the  posterior  aspect 
of  the  thorax,  where  it  extends  from  the  second  to  the  seventh 
rib,  being  separated  b}^  muscles  from  the  thoracic  wall.  It  consists 
of  a  body  and  three  processes,  namely,  a  spine,  an  acromion  and 
a  coracoid  process. 

The  body  is  a  thin  triangular  plate,  and  it  presents  two  surfaces, 
three  borders,  and  three  angles.  The'  anterior  surface,  venter,  or 
subscapular  fossa  is  concave,  and  the  bone  forming  it  is  for  the 
most  part  thin,  except  near  the  external  or  axillary  border,  where 
there  is  a  thick,  round,  elongated  ridge.  It  gives  origin  to  the 
subscapularis,  except  (i)  along  the  anterior  aspect  of  the  base  from 
the  superior  to  the  inferior  angle,  where  the  serratus  magnus  is 
inserted,  and  (2)  over  the  front  of  the  neck.  The  venter  is  crossed 
by  three  or  four  oblique  ridges,  which  extend  upwards  and  outwards 
from  the  base,  and  give  attachment  to  tendinous  septa  intersect- 
ing the  subscapularis  muscle. 

'  The  posterior  surface  or  dorsum  is  irregularly^  convex,  and  is  divided 
into  two  unequal  parts  by  the  spine.  The  upper  division,  along  with 
the  superior  surface  of  the  spine,  forms  the  supraspinous  fossa.  It 
represents  about  one-fourth  of  the  dorsum,  and  gives  origin  over  its 
inner  two-thirds  to  the  supraspinatus.  In  the  region  of  the  neck 
it  presents  a  nutrient  foramen  for  a  branch  of  the  suprascapular 
artery.  The  lower  division,  along  with  the  inferior  surface  of  the 
spine,  forms  the  infraspinous  fossa,  and  it  represents  about  three- 
fourths  of  the  dorsum.  Towards  the  external  or  axillary  border 
it  presents  an  elongated  concavity,  external  to  which  is  an  oblique 
line  extending  from  its  upper  end  downwards  and  inwards  to  the 
base  near  the  inferior  angle.  The  infraspinous  fossa,  as  far  out 
as  this  oblique  line,  gives  origin  to  the  infraspinatus,  except  at 
the  upper  and  outer  part,  and  it  presents  a  nutrient  foramen 
superiorly,  close  to  the  spine  near  the  centre,  for  a  branch  of  the 
dorsalis  scapulae  artery.  The  oblique  line  marks  off  impressions  for 
the  teres  muscles  and  dorsalis  scapulae  artery,  as  follows:  the  teres 
minor  arises  from  about  the  upper  two-thirds,  near  the  centre  of 
which  there  is  a  groove  for  the  dorsalis  scapulae  artery,  and  the 

II 


1 62 


A  MANUAL  OF  ANATOMY 


teres  major  arises  from  about  the  lower  third.  The  impression 
for  the  latter  muscle  is  oval ;  it  extends  on  to  the  back  of  the  inferior 
angle,  and  it  is  separated  from  the  impresssion  for  the  teres  minor 
by  a  short  rough  line.  This  line  gives  attachment  to  an  inter- 
muscular septum  which  separates  the  teres  muscles,  and  the  oblique 
line  to  a  septum  which  separates  these  muscles  from  the  infra- 
spinatus. The  supra-  a.nd  infraspinous  fossse  communicate  with 
each  other  by  means  of  the  great  scapular  notch,  which  lies  outside 


Coracoid  Process 
Cla\  icular         j 
Acromion  Process       Facet  i 

Deltoid 


Suprascapular  Notch 

Superior  Angle 


Upper  part  of 
Serratus  Magnus 


Short  Head  of  Biceps 

and 

Coraco-brachialis 


Infraglenoid  Ridge 

and  Long  Head 

of  Triceps 


Lower  part  of 
Serratus  Magnus 


Inferior  Angle 

Fig.  97. — The  Right  Scapula  (Anterior  Vie'w). 

the  short  external  border  of  the  spine,  and  transmits  the  supra- 
scapular artery  and  nerve. 

The  borders  are  superior,  internal  or  vertebral,  and  external  or 
axillary.  The  superior  border,  which  is  the  shortest  and  thinnest, 
extends  from  the  superior  angle  to  the  coracoid  process.  Close 
to  that  process  it  presents  the  suprascapular  notch.  This  is 
converted  into  a  foramen  by  the  suprascapular  or  transverse 
ligament,   which    sometimes    undergoes    ossification.     The    supra- 


THE  BONES  OF  THE  UPPER  LIMB  163 

scapular  nerve  passes  backwards  beneath  the  ligament,  and  the 
suprascapular  artery  over  it,  whilst  the  posterior  belly  of  the 
omo-hyoid  arises  from  its  inner  part  and  from  the  adjacent 
portion  of  the  superior  border.  The  internal  or  vertebral  border 
is  known  as  the  base.  It  is  the  longest,  intermediate  in  thickness, 
and  extends  from  the  superior  to  the  inferior  angle.  It  is 
convex,  and  is  divisible  into  three  parts.  One  part  represents 
the  base  of  the  small  triangular  surface  by  which  the  spine 
arises  from  the  vertebral  border,  and  it  gives  insertion  to  the 
rhomboideus  minor  ;  another  extends  from  this  to  the  superior 
angle,  and  gives  insertion  to  the  levator  anguli  scapulae  ;  and  the 
third  extends  downwards  to  the  inferior  angle,  and  gives  insertion 
to  the  rhomboideus  major.  On  the  ventral  aspect  close  to  this 
border  there  is  a  long  narrow  linear  impression,  which  widens 
towards  the  superior  and  inferior  angles,  and  gives  insertion  to 
the  serratus  magnus.  The  external  or  axillary  border,  which  is  the 
thickest  and  intermediate  in  length,  extends  from  the  inferior 
angle  to  the  lower  margin  of  the  glenoid  cavity.  Below  that 
cavity  it  presents  a  rough  impression,  an  inch  long,  called  the  infra- 
glenoid  ridge,  which  gives  origin  to  the  long  head  of  the  triceps, 
and  a  little  below  this  a  groove  for  the  dorsalis  scapulae  artery, 
which  also  marks  the  dorsal  aspect.  The  ventral  aspect  of  the 
bone  close  to  this  l)order  presents  a  groove  over  the  upper  two- 
thirds,  which  gives  origin  to  many  fibres  of  the  subscapularis. 

The  angles  are  superior,  inferior,  and  external.  The  superior 
angle,  which  is  thin,  is  situated  at  the  meeting  of  the  superior 
and  vertebral  borders,  and  it  forms  the  highest  part  of  the  body, 
being  on  a  level  with  the  second  rib.  Its  ventral  aspect  gives 
insertion  to  a  part  of  the  serratus  magnus,  and  its  edge  to  a  portion 
of  the  levator  anguli  scapulae.  The  inferior  angle,  somewhat  thick 
and  round,  is  situated  at  the  meeting  of  the  vertebral  and  axillary 
borders,  and  it  forms  the  lowest  part  of  the  bone,  being  on  a  level 
with  the  seventh  rib.  Its  ventral  aspect  gives  insertion  to  a  part 
of  the  serratus  magnus,  and  its  dorsal  aspect  gives  origin  to  a 
portion  of  the  teres  major.  Below  the  impression  for  the  latter 
muscle  there  is  sometimes  a  rough  semilunar  marking  for  a  slip  of 
origin  of  the  latissimus  dorsi.  The  external  angle,  which  is  massive. 
is  situated  at  the  upper  end  of  the  axillary  border.  It  forms  the 
head  of  the  bone,  and  supports  the  glenoid  cavity,  which  articulates 
with  the  head  of  the  humerus. 

The  glenoid  cavity,  so  named  from  its  shallowness,  is  {)yriform, 
with  the  narrow  end  upwards,  and  its  direction  is  outwards  and 
forwards.  Its  margin  is  slightly  elevated  and  rough  for  the  glenoid 
ligament,  and  immediately  outside  the  margin  the  capsular  ligament 
of  the  shoulder- joint  is  attached.  Superiorly  it  presents  a  small 
rough  elevation,  called  the  supraglenoid  tubercle,  which  gives  origin 
to  the  long  head  of  the  biceps.  The  neck  is  the  constricted  portion 
which  extends  from  the  suprascapular  notch  to  a  point  immediately 
above  the  infraglenoid  ridge,  and  it  is  most  evident  posteriorly, 

II — 2 


164 


A  MANUAL  OF  ANATOMY 


where  it  forms,  with  the  external  border  of  the  spine,  the  great 
scapular  notch.  In  this  latter  situation  there  are  numerous  fora- 
mina for  branches  of  the  suprascapular  artery. 

The  spine  is  situated  on  the  dorsum  of  the  bone,  which  it  crosses  in 
a  direction  outwards  and  slightly  upwards.  It  commences  at  the 
vertebral  border  in  a  flat  triangular  surface,  over  which  the  tendon 
receiving  the  lower  fibres  of  the  trapezius  glides,  with  the  interven- 
tion of  a  bursa.     It  soon  becomes  very  prominent,  and  at  its  outer 

Suprascapular  Coracoid 
Posterior  Belly  of  Onio-hyoid       Notch  Process      Trapezius 

\       1  /  '1 

Supraspinous  Fossa  and  Supraspinatus 

Superior  Angle  I 

Levator  Anguli  Scapula;  \ I  ,  ^         ,  ™-"v    y^^  t»i 

'     '         ^         "™  ^    '""^  ^"^     Acromion 

Process 


Spine 

For  Tendon 

of  Trapezius, 

Rhomboideus  Minor 


Rhomboideus  ISIajor 
Infraspinous  Fossa 
and  Infraspinatus 

Groove  for  Dorsalis 
Scapulae  Artery 


-  Deltoid 

Great 

Scapular  Notch 
Glenoid  Cavity 


Infraglenoid  Ridge 

and  Long  Head 

of  Triceps 


^~-~  Axillary  Border 
^  Teres  Minor 


"'^,  Teres  Major 

■.Inferior  Angle 
Latissimus  Dorsi 

Fig.  98. — The  Right  Scapula  (Posterior  View). 


extremity  it  undergoes  a  slight  twist  and  forms  the  acromion  process. 
It  is  triangular,  and  compressed  from  above  downwards.  The 
superior  surface  forms  part  of  the  supraspinous  fossa,  and  gives  origin 
to  fibres  of  the  supraspinatus,  whilst  the  inferior  surface  forms  part  of 
the  infraspinous  fossa,  and  gives  origin  to  fibres  of  the  infraspinatus. 
The  external  border,  which  is  short,  bounds  internally  the  great 
scapular  notch.  The  anterior  border  is  continuous  with  the  body 
of  the  bone.  The  posterior  border  or  crest  presents  an  upper  lip,  which 
gives  insertion  to  part  of  the  trapezius,  a  lower  lip,  giving  partial 


THE  BONES  OF  THE  UPPER  LIMB  165 

origin  to  the  deltoid,  and  an  intervening  rough  surface  which  is 
encroached  upon  by  the  tendinous  fibres  of  these  two  muscles. 
The  upper  lip  is  often  very  projecting  at  its  inner  end,  where  the 
tendon  receiving  the  lower  fibres  of  the  trapezius  is  inserted. 

The  acromion  process  is  situated  at  the  outer  extremity  of 
the  spine,  and  its  direction  is  outwards,  upwards,  and  forwards, 
so  as  to  overhang  the  glenoid  cavity.  It  is  somewhat  triangular, 
and  is  compressed  from  above  and  behind  downwards  and 
forwards.  The  postero-sitperior  surface,  which  is  rough,  gives 
origin  at  its  lower  and  inner  part  to  some  fibres  of  the  deltoid,  and 
elsewhere  is  subcutaneous.  The  antero-inferior  surface,  which  is 
smooth  and  concave,  overhangs  the  glenoid  cavity,  and  is  related 
to  the  subacromial  bursa.  The  outer  border  is  continuous  with  the 
lower  lip  of  the  posterior  border  of  the  spine,  where  there  is  a  pro- 
jection called  the  acromial  angle,  and  this  outer  border  gives  origin 
to  a  portion  of  the  deltoid.  The  inner  border  is  continuous  with  the 
upper  lip  of  the  posterior  border  of  the  spine,  near  which  it  gives 
insertion  to  a  part  of  the  trapezius,  whilst  near  the  tip  of  the  acro- 
mion it  presents  an  oval  facet  for  the  outer  extremity  of  the  clavicle. 
The  upper  and  lower  margins  of  this  facet  are  rough  for  the  acromio- 
clavicular ligaments.  The  tip  or  apex  of  the  process  is  situated 
at  the  meeting  of  the  outer  and  inner  borders.  The  acromion  pro- 
cess is  pierced  by  many  arterial  twigs  derived  from  the  acromial  rete. 

The  coracoid  process,  which  is  strong  and  curved,  springs 
from  the  upper  aspect  of  the  head,  immediately  external  to 
the  suprascapular  notch.  It  is  directed  at  first  upwards  and 
forwards  for  about  h  inch,  and  then,  bending  sharply,  it 
is  directed  forwards  and  outwards  to  terminate  in  a  blunt  tip. 
The  ascending  portion  is  compressed  from  before  backwards.  Its 
anterior  surface  is  related  to  the  subscapularis,  and  the  posterior 
to  the  supraspinatus.  Its  outer  border  gives  attachment  to  a 
portion  of  the  coraco  -  humeral  ligament,  and  the  inner  border, 
which  bounds  the  suprascapular  notch  externally,  gives  attachment 
at  its  upper  part  to  the  suprascapular  or  transverse  ligament. 
The  horizontal  portion  of  the  process  is  compressed  from  above 
downwards.  Its  antero -internal  border,  which  is  long  and  convex, 
and  the  adjacent  portion  of  the  superior  surface,  give  insertion 
anteriorly  to  the  pectoral  is  minor,  whilst  posteriorly  they  give 
attachment  to  the  costo-coracoid  membrane  and  ligament.  The 
postero-external  border,  which  is  short,  receives  the  fibres  of  the 
coraco-acromial  ligament,  and  gives  attachment  to  a  portion  of  the 
coraco-humeral  ligament.  At  the  back  part  of  the  antero-internal 
border  there  is  the  conoid  impression  for  the  conoid  ligament.  On 
the  back  part  of  the  suj^erior  surface  there  is  the  trapezoid  ridge 
for  the  trapezoid  ligament,  which  ridge  extends  forwards  and  out- 
wards from  the  conoid  im])ression.  The  inferior  surface  of  the 
horizontal  j)ortion  is  smooth  and  concave.  The  tip  or  apex,  which 
is  blunt,  gives  origin  to  the  conjoined  short  head  of  the  biceps  and 
coraco-brachialis. 


i65 


A  MANUAL  OF  ANATOMY 


The  coracoid  process  of  man  represents  the  coracoid  hone  of 
monotremata  and  lower  vertebrates. 

The  scapula  derives  its  blood-supply  from  the  dorsalis  scapulae, 
suprascapular,  and  posterior  scapular,  arteries. 

Articulations. — By  its  acromion  process  with  the  outer  extremity 
of  the  clavicle,  and  by  the  glenoid  cavity  with  the  head  of  the 
humerus. 

Structure. — ^The  scapula  is  a  flat  or  tabular  bone,  and  is  composed 


Appears  about  the  i5th  Year 
and  joins  about  25 


Subcoracoid  Epiphysis.     Appears  at 
roth  \  ear,  and  joins  at  i5 


Coracoid  Element.  Appears  in  ist  Year, 
and  joins  at  15 
I  Appear  about  the  i6th  Year, 
■'      and  join  Spine  about  25 


Line  of  junction  of 
Coracoid  Element 


--.  Appears  about  the  i6th  Year, 
and  joins  about  25 

Fig.  99. — Ossification  of  the  Scapula. 

of  two  tables  of  compact  bone.  In  the  head,  axillary  border, 
inferior  angle,  and  processes  there  is  cancellated  tissue  between 
the  two  tables,  but  in  the  central  portions  of  the  supra-  and  infra- 
spinous  fossae  there  is  none,  and  the  two  tables  coalesce,  so  that 
the  bone  is  very  thin  and  transparent. 

Varieties. — (i)    Suprascapular     foramen.       (2)   Fenestrated     scapula,     pre- 
senting one  or  more  perforations  in  the  subscapular  fossa.      (3)  Separation  of 


THE  BONES  OF  THE   UPPER  LIMB  167 

the  acromion  process,  which  may  be  connected  witli  the  spine  by  a  plate  of 
cartilage,  or  b\-  iibrous  tissue.  (4)  Imperfect  ankylosis  of  the  coracoid  process, 
which,  however,  is  extremely  rare. 

Ossification. — The  scapula  has  one  primary  centre  and  eleven  secondary 
centres.  The  primary  centre  appears  in  the  body  near  the  neck  about  the 
Sth  week. 

The  coracoid  process,  cartilaginous  at  birth,  has  four  secondary  centres — 
coracoid,  accessory  coracoid,  supracoracoid,  and  apical.  The  coracoid  centre 
appears  in  the  end  of  the  ist  year,  and  gives  rise  to  the  chief  part  o.  the  process, 
which  joins  about  the  i5//«  year.  The  accessory  coracoid  centre  appears  about 
puberty,  and  soon  joins  the  main  coracoid.  It  forms  the  triangular  part  of 
the  process  wliich  enters  shghtly  into  the  extreme  Jtpper  and  inner  part  of  the 
glenoid  cavity.  The  supracoracoid  centre  appears  about  the  18^/2  year,  and 
forms  a  thin  laminar  epiphysis  on  the  upper  surface  of  the  process.  It  gives 
about  the  2^th  year.  The  apical  centre  appears  about  the  iStth  year.and 
forms  an  epiphysis  which  caps  the  tip  of  the  process,  and  joins  about  the 
2^th  year. 

Acromion  Process. — The  inner  or  basal  portion  is  ossified  from  the  spine, 
which  in  turn  is  ossified  from  the  primary  centre  for  the  body.  The  greater 
portion  constitutes  an  epiphysis,  which  has  two  secondary  centres.  These 
appear  about  the  i6th  year  and  soon  join.  The  acromial  epiphysis  usually 
joins  the  rest  of  the  process  about  the  2Sth  year  or  earlier.  Union,  however, 
may  not  take  place,  and  then  the  acromial  epiphysis  forms  a  separate  acromial 
bone,  connected  with  the  rest  of  the  process  by  cartilage  or  by  fibrous  tissue, 
and  this  condition  may  simulate  a  fracture. 

Glenoid  Cavity. — The  fundus  or  bed  of  this  cavity  is  ossified  from  the 
primary  centre  for  the  body,  and  its  extreme  upper  and  inner  part  is  formed 
from  the  accessory  coracoid  centre.  Besides  these  the  cavity  has  two  special 
secondary-  centres — superior  and  inferior.  The  superior  glenoid  or  sub- 
coracoid  centre  appears  about  the  loth  year,  and  it  joins  the  fundus  or  bed 
of  the  fossa  about  the  i6th  year.  The  inferior  glenoid  centre  appears  about 
the  16th  year,  and  forms  the  glenoid  epiphysial  plate.  It  joins  about  the 
20th  year,  and  gives  rise  to  the  slight  concavity  of  the  fossa. 

The  other  secondary  centres  are  allocated  as  follows:  (i)  Posterior  border 
of  spine;  (2)  inferior  angle;  (3)  base.  These  ceiitres  appear  about  the  i6th 
year,  and  join  about  the  25th  year. 


The  Humerus. 

The  humerus  extends  from  the  shoulder  to  the  elbow,  its  direction 
being  downwards  and  slightly  inwards.  It  is  a  long  bone,  and  is 
divisible  into  a  shaft  and  two  extremities,  upper  and  lower. 

The  upper  extremity  includes  the  head,  anatomical  neck,  great  and 
small  tuberosities,  commencement  of  the  bicipital  groove,  and 
surgical  neck.  The  head,  which  is  almost  hemispherical,  is  smooth, 
convex,  and  covered  by  cartilage.  Its  direction  is  upwards, 
inwards,  and  backwards,  and  it  articulates  with  the  glenoid  cavity 
of  the  scapula.  The  anatomical  neck  is  the  constriction  immedi- 
ately beyond  the  cartilage  of  the  head.  It  is  best  marked  above, 
especially  between  the  head  and  great  tuberosity,  and  it  gives 
attachment  to  the  capsular  ligament  of  the  shoulder-joint.     It  is 


A  MANUAL  OF  ANATOMY 


Anatomical  Neck 
A  Large  Nutrient  Foramen  ^ 
Great  Tuberosity  and 
Supraspinatus 

Infraspinatus 
Surgical  Neck- 


Pectoralis  Major ' 


Head 


Small  Tuberosity  and  Subscapularis 


Deltoid- 


m 


[ .Bicipital  Groove 

—  Latissimus  Dorsi 

—  Teres  Major 


— Coraco-brachialis 

t" — Medullary  Foramen 


Brachio-rad  ial  is a 


Brachialis  Amicus  -- 
External  Supracondylar      dge.. 


-Internal  Supracondylar  Ridge 


Extensor  Carpi  Radialis  Longior.- 


Radial  Fossa 


External  Epicondyle  | 


Common  Origin  of  / 

Extensor  Carpi  Radialis  Brevior' 
Extensor  Communis  Digitorum 
Extensor  Minimi  Digiti 
Extensor  Carpi  Ulnaris,  and 
Supinator  Radii  Brevis 


Capitellum 


Trochlea 


,Coronoid  Fossa 

, Superficial  Head  of  Pronator 

Radii  Teres 

Internal  Epicondyle 


Common  Origin  of 
••Flexor  Carpi  Radialis 
Palmaris  Longus 
Flexor  Sublirais  Dieitorum,  and 
Small  Head  of  Flexor  Carpi 
Ulnaris 


Fig.   ioo. — The  Right  Humerus  (Anterior  View). 


THE  BONES  OF  THE  UPPER  LIMB  169 

pierced  by  numerous  nutrient  foramina.  The  great  tuberosity  is 
situated  obliquely  on  the  outer  surface,  immediately  beyond  the 
anatomical  neck.  It  presents  three  fiat  muscular  impressions — an 
upper  for  the  insertion  of  the  supraspinatus,  a  middle  for  the  infra- 
spinatus, and  a  lower  for  the  teres  minor,  which  latter  muscle  con- 
tinues to  take  insertion  into  a  rough  marking  on  the  shaft  for  at 
least  \  inch  below  the  lower  impression.  The  small  tuberosity  is 
an  oval  prominence  situated  on  the  anterior  aspect,  immediately 
beyond  the  anatomical  neck.  It  gives  insertion  to  the  subscapu- 
laris,  which  continues  to  take  insertion  into  the  adjacent  part  of 
the  shaft  for  about  1  inch.  The  commencement  of  the  bicipital 
groove,  which  lodges  the  long  tendon  of  the  biceps,  lies  between  the 
two  tuberosities,  where  it  is  bridged  over  by  the  transverse  humeral 
ligament.  It  presents  a  large  nutrient  foramen  close  to  the  great 
tuberosity  for  an  offset  of  the  ascending  branch  of  the  anterior 
circumflex  artery.  The  surgical  neck  is  the  constriction  below  the 
tuberosities. 

The  upper  extremity  of  the  humerus  receives  its  principal  blood- 
supply  from  the  anterior  and  posterior  circumflex  arteries. 

The  shaft  is  almost  cylindrical  in  its  upper  half,  but  it  is  laterally 
expanded  and  triangular  in  its  lower  half.  The  anterior  aspect 
presents  superiorly  the  bicipital  groove,  which  commences  between 
the  tuberosities,  where  it  is  deep,  and  passes  downwards  and  slightly 
inwards,  terminating  about  the  junction  of  the  upper  and  middle 
thirds.  It  is  bounded  by  two  rough  ridges,  outer  and  inner.  The 
outer  bicipital  ridge,  which  is  the  more  prominent,  gives  insertion 
over  about  its  lower  three- fourths  to  the  pectoralis  major,  this  portion 
being  called  the  pectoral  ridge.  It  is  in  line  with  the  anterior  border 
of  the  lower  half  of  the  shaft.  The  inner  bicipital  ridge  gives  inser- 
tion over  about  its  lower  two-thirds  to  the  teres  major,  this  portion 
being  known  as  the  teres  ridge.  It  is  in  line  with  the  internal  border 
of  the  lower  half  of  the  shaft.  The  floor  of  the  groove  over  about 
its  middle  third  gives  insertion  to  the  latissimus  dorsi.  The  groove 
is  occupied  by  the  long  tendon  of  the  biceps,  invested  by  a 
tubular  prolongation  of  the  synovial  membrane  of  the  shoulder- joint ; 
and  the  ascending  branch  of  the  anterior  circumflex  artery.  The 
outer  aspect  of  the  shaft  presents  a  rough  V-shaped  mark,  called  the 
deltoid  impression,  for  the  insertion  of  the  deltoid.  The  point  of 
the  V,  which  is  embraced  by  two  slips  of  the  brachialis  anticus,  is 
at  the  centre  of  the  shaft,  whence  it  extends  upwards  for  about 
2  inches.  Its  anterior  margin  is  in  line  with  the  pectoral  ridge,  and 
its  posterior  margin  bounds  superiorly  the  lower  part  of  the  spiral 
groove.  On  the  inner  aspect  of  the  shaft,  about  the  centre,  there  is  a 
rough  line  about  ih  inches  long,  placed  in  the  course  of  the  internal 
border,  for  the  insertion  of  the  coraco-breichialis.  Immediately 
below  this  line  is  the  principal  medullary  foramen  for  the  nutrient 
or  medullary  branch  of  the  brachial  artery,  the  canal  to  which  it 
leads  being  directed  downwards.  The  posterior  and  external  aspects 
of  the  u])p<'r  part  of  the  shaft  present  a  winding  groove,  called  the 


170 


A  MANUAL  OF  ANATOMY 
Head 


Infraspinatus 


Anatomical  Neck.. 


Teres  Minor 


Surgical  Neck ^m' ' 


External  Head  of  Triceps 


_,  A  Nutrient  Foramen 

JDeltoid  Impression  and  Deltoid 


Spiral  Groove 


Brachialis  Amicus 


Internal  Head  of  Triceps. 


/I        '' 
/  ■  V       / 

Olecranon  Fossae 

External  Epicondyle 
Anconeus 

Groove  for  Ulnar  Nerve 

Trochlea 

Fig.   lor. — The  Right  Humerus  (Posterior  View). 


Internal  Epicondyle  and 

Small  Head  of  Flexor 

Carpi  Ulnaris 


THE  BONES  OF  THE   UPPER  LIMB  171 

spiral  groove,  for  the  musculo-spiral  nerve  and  superior  profunda 
vessels.  It  commences  in  the  upper  third  posteriorly,  and  is  directed 
downwards  and  forwards  on  to  the  external  surface,  where  it  ter- 
minates a  little  below  and  behind  the  apex  of  the  deltoid  impression. 
The  lower  part  of  this  groove  is  occupied  by  a  pointed  slip  of  the 
brachialis  anticus.  In  the  upper  part  of  the  groove  there  is  usually 
a  nutrient  foramen  for  a  branch  of  the  superior  profunda  arterj^ 
On  the  posterior  aspect  of  the  shaft,  over  about  its  upper  third, 
external  to  the  spiral  groove,  there  is  a  rough  marking  which  gives 
origin  to  the  external  head  of  the  triceps,  extending  as  high  as 
the  lower  part  of  the  insertion  of  the  teres  minor.  The  internal 
head  of  the  triceps  commences  to  arise  in  a  pointed  manner  from  the 
back  of  the  shaft  internal  to  the  spiral  groove,  where  it  reaches  a 
little  above  and  behind  the  lower  border  of  the  tendon  of  the  teres 
major. 

The  lower  half  of  the  shaft,  being  triangular,  presents  three 
surfaces  and  three  borders.  The  fosterior  surface,  which  is  fiat, 
terminates  at  the  olecranon  fossa,  and  it  gives  origin  to  most  of 
the  fibres  of  the  internal  head  of  the  triceps.  The  external  and 
internal  surfaces,  as  well  as  the  anterior  border  which  separates 
them,  give  origin  to  the  brachialis  anticus.  The  anterior  border, 
which  is  round,  separates  the  lateral  surfaces,  and  is  in  line  with  the 
anterior  margin  of  the  deltoid  impression,  and,  above  this,  with  the 
outer  bicipital  ridge.  The  external  border  is  called  the  external  supra- 
condylar ridge.  It  is  sharp  and  prominent,  and  extends  from  the 
external  epicondyle  to  the  spiral  groove.  It  gives  attachment  to 
the  external  intermuscular  septum.  Anteriorly  its  upper  two-thirds 
give  origin  to  the  brachio-radialis  (supinator  radii  longus),  and  the 
lower  third  to  the  extensor  carpi  radialis  longior.  Posteriorly  it 
gives  origin  to  the  inner  head  of  the  triceps.  The  internal  border 
forms  the  internal  supracondylar  ridge,  and  is  not  so  prominent  as 
the  external.  It  commences  at  the  internal  epicondyle,  and  it  can 
be  followed  up  through  the  line  for  the  insertion  of  the  coraco- 
brachialis  into  the  inner  bicipital  ridge.  It  gives  attachment  to 
the  internal  intermuscular  septum.  Anteriorly  it  gives  origin  to  the 
brachialis  anticus,  posteriorly  to  the  inner  head  of  the  triceps,  and 
in  its  lower  part  to  some  fibres  of  the  superficial  head  of  the  pronator 
radii  teres.  The  internal  surface  of  the  shaft,  in  front  of  the  internal 
supracondylar  ridge  and  about  2^  inches  above  the  internal  epicon- 
dyle, sometimes  presents  a  sharp  spur-like  projection  directed  down- 
wards, called  the  supracondylar  process.  When  present  it  gives 
attachment  to  a  fibrous  band  which  passes  to  the  internal  epicon- 
dyle, and  gives  origin  to  a  third  head  of  the  pronator  radii  teres. 
In  such  cases  the  band  forms  an  arch  through  which  the  median 
nerve  passes,  and  frequently  the  brachial  artery.  The  supra- 
condylar process  represents  a  portion  of  bone  which  forms  a  supra- 
condylar foramen  in  many  carnivora — e.g.,  the  felidce. 

The  lower  extremity  presents  at]_either  side  the  internal  and  ex- 
ternal cpiccjiidyhjs,  and  infcriorly  a  transversely  elongated  articular 


172  A  MANUAL  OF  ANATOMY 

surface  covered  by  cartilage,  and  divided  by  a  vertical  curved 
ridge  into  an  external  part,  called  the  capitellum,  and  an  internal, 
called  the  trochlea.  Above  the  capitellum  in  front  there  is  a  rough 
transverse  depression,  called  the  radial  fossa.  Above  the  trochlea 
in  front  is  the  coronoid  fossa,  and  above  it  posteriorly  is  the  olecranon 
fossa. 

The  internal  epicondyle  {epitrochlea)  is  very  prominent,  and  is 
directed  inwards  and  slightly  backwards.  Its  lower  part  and  the 
adjacent  portions  of  its  anterior  and  posterior  aspects  give  attach- 
ment to  the  internal  lateral  ligament  of  the  elbow- joint.  Its  anterior 
aspect  gives  origin  to  the  common  tendon  of  the  superficial  head  of 
the  pronator  radii  teres,  flexor  carpi  radialis,  palmaris  longus,  part 
of  the  flexor  sublimis  digitorum,  and  one  head  of  the  flexor  carpi 
ulnaris.  Behind  the  internal  epicondyle,  close  to  the  trochlea,  is  the 
ulnar  groove,  through  which  the  ulnar  nerve  passes. 

The  external  epicondyle  is  much  less  prominent  than  the  internal. 
Anteriwly  it  gives  origin  to  the  common  tendon  of  the  extensor 
carpi  radialis  brevior,  extensor  communis  digitorum,  extensor  minimi 
digiti,  extensor  carpi  ulnaris,  and  supinator  radii  brevis.  Posteriorly 
it  presents  an  impression  for  the  anconeus,  and  inferiorly  a  depres- 
sion near  the  capitellum  for  the  external  lateral  ligament  of  the 
elbow-joint. 

The  capitellum  mainly  takes  the  form  of  a  rounded  eminence. 
It  is  limited  to  the  anterior  and  inferior  aspects  of  the  bone,  and 
articulates  with  the  cup-shaped  depression  on  the  head  of  the 
radius.  Internal  to  the  rounded  portion  there  is  a  groove  for  the 
play  of  the  inner  convex  part  on  the  head  of  the  radius.  The 
radial  fossa  receives  the  anterior  margin  of  the  head  of  the  radius 
in  complete  flexion  of  the  elbow- joint. 

The  trochlea  is  pulley-shaped,  and  turns  completely  round  from 
the  front  to  the  back  of  the  bone,  becoming  rather  broader  pos- 
teriorly. It  is  concave  from  side  to  side,  and  convex  from  before 
backwards.  The  internal  border  is  more  prominent  and  thicker 
than  the  external,  and  extends  lower  down.  As  viewed  from 
before,  the  borders  are  inclined  downwards  and  slightly  inwards, 
but  posteriorly  they  incline  upwards  and  slightly  outwards,  and  so 
the  trochlea  is  here  brought  into  the  centre  of  the  bone.  The 
trochlea  articulates  with  the  great  sigmoid  cavity  of  the  ulna.  The 
coronoid  fossa  receives  the  coronoid  process  of  the  ulna  in  flexion 
of  the  elbow-joint,  and  the  anterior  ligament  is  attached  just  above 
it.  The  olecranon  fossa,  much  larger  than  the  coronoid,  receives  the 
olecranon  process  of  the  ulna  in  extension  of  the  joint,  and  its  margins 
give  attachment  to  the  posterior  ligament.  The  portion  of  bone 
which  separates  the  two  fossae  is  thin,  and  is  sometimes  perforated 
by  a  foramen,  called  the  supratrochlear  foramen. 

In  the  vicinity  of  the  lower  extremity  there  are  numerous  nutrient 
foramina  for  branches  of  the  superior  and  inferior  profunda  and 
anastomotica  magna  of  the  brachial,  radial  and  ulnar  recurrent, 
and  interosseous  recurrent,  arteries. 


THE  BONES  OF  THE   UPPER  LIMB 


173 


Articulations. — Superiorly  with  the  scapula,  and  inferiorly  with 
the  radius  externally,  and  ulna  internally. 

Structure. — The  shaft  is  composed  of  compact  bone,  which  is 
thicker  at  the  centre  than  at  the  extremities.  It  contains  a  medul- 
lary canal  lined  with  a  thin  coating  of  cancellated  tissue.  The 
articular  extremities  are  filled  with  cancellated  tissue,  except  at  the 
surface,  where  there  is  a  thin  layer  of  compact  bone. 

Varieties. — These  are  (i)  a  supracondylar  process,  and  (2)  a  supratrochlear 
foramen. 

Ossiflcation. — The  humerus  ossifies  in  cartilage  from  one  primary,  and  six 
(sometimes  seven)  secondary,  centres.  The  primary  centre  appears  at  the 
middle  of    the  shaft  in   the   eighth   week  of  intra-uterine  Ufe.     At  birth  the 

Appears  in  the  ist  Year 

/V--*-\-- ■•'^PFears  in  the  3rd  Year 
Appears  in  the  5th  Year 

All  three  coalesce  at  the 
6th  Year,  and  join  at  20 


Appears  at  the  8th  Week 
(intra-uterine) 


Appears  in  the  14th  Year  .  ^  .'J^-^  -  (^—Appears  in  the  5th  Year, 

and  joins  at  18 

Appears  in  the  3rd  Year      Appears  in  the  12th  Year 

The  External  Epicondyle,  Capitellum,  and  Trochlea, 
having  previously  coalesced,  join  at  17 

Fig.   102. — Ossification  of  the  Humerus. 


shaft  is  ossified,  but  the  extremities  are  cartilaginous.  The  superior  extremity 
is  ossified  from  two  or  three  secondary  centres.  The  centre  for  the  head 
appears  in  the  first  year  (sometimes  just  before  birth),  and  that  for  the  great 
tuberosity  in  the  third  year.  The  small  tuberosity  may  have  a  separate 
centre,  and,  if  so,  it  appears  in  the  fijlh  year,  or  it  may  be  ossified  from  the 
centre  for  the  great  tuberosity.  The  upper  epiphyses  join  to  form  one  com- 
pound epiphysis  in  the  sixth  year,  and  this  unites  with  the  shaft  in  the 
twentieth  year.  The  lower  extremity  is  ossified  from  four  secondary  centres, 
as  follows  :  one  for  the  capitellum  and  outer  half  of  the  trochlea  appearing 
in  the  third  year  ;  one  for  the  internal  epicondyle  in  the  fijlh  year  ;  one  for 
the  inner  half  of  the  trochlea  in  the  twelfth  year  ;  and  one  for  the  external 
epicondyle  in  the  fourteenth  year.  The  trochlea,  capitellum,  and  external 
epicondyle  join  to  form  one  compound  epiphysis,  and  this  unites  with  the 
sliaft  in  the  seventeenth  year.  The  internal  epicondyle  unites  with  the  shaft, 
as  an  independent  epiphysis,  in  the  eighteenth  year. 

The  law  of  ossiflcation  applicable  to  long  bones  with  an  epiphysis 
or  epiphyses  at  cither  end  is  as  follows  :  the  epipJiysis  or  epip/iyses, 


174  A  MANUAL  OF  ANATOMY 

at  the  end  towards  which  the  medtillary  foramen  and  the  canal  to  which 
it  leads  are  directed,  are  the  last  to  show  signs  of  ossification,  but  they 
are  the  first  to  join  the  shaft.  The  only  exception  to  this  rule  occurs 
in  the  fibula. 

The  Radius. 

The  radius  is  the  external  bone  of  the  forearm  (which  is 
assumed  to  be  in  a  position  of  supination).  It  is  parallel  with, 
and  shorter  than,  the  ulna,  and  extends  from  the  elbow  to  the 
wrist.  It  is  a  long  bone,  and  is  divisible  into  a  shaft  and  two 
extremities. 

The  upper  extremity,  which  is  small,  presents  a  head  and  neck. 
The  head  is  disc-shaped,  and  covered  by  cartilage,  both  on  its  upper 
surface  and  circumference.  The  upper  surface,  at  its  centre, 
presents  a  depression  which  articulates  with  the  rounded  portion 
of  the  capitellum  of  the  humerus  in  flexion  of  the  elbow-joint. 
Around  this  depression  the  surface  is  convex,  especially  on  the 
inner  side,  and  this  portion  glides  on  the  inner  grooved  part  of  the 
capitellum.  The  circumferential  cartilage  is  deeper  on  the  inner 
aspect  than  elsewhere,  and  this  portion  articulates  with  the  small 
sigmoid  cavity  of  the  ulna,  whilst  the  remainder  plays  within  the 
orbicular  ligament.  The  constricted  portion  below  the  head  is 
called  the  neck.  It  is  cylindrical,  and  its  upper  part  is  embraced 
by  the  orbicular  ligament,  whilst  beyond  this  on  the  outer  aspect 
it  gives  insertion  to  a  few  fibres  of  the  supinator  radii  brevis.  The 
upper  extremity  presents  several  nutrient  foramina  for  branches 
of  the  radial  recurrent  and  interosseous  recurrent  arteries. 

The  shaft  increases  in  size  from  above  downwards,  and  is  curved, 
the  convexity  being  directed  outwards  and  slightly  backwards. 
This  curve  imparts  elasticity  to  the  bone,  and  guards  it  against 
the  shocks  to  which  it  is  so  much  exposed  from  the  fact  that  it 
supports  the  hand.  The  shaft  is  triangular,  and  presents  superiorly, 
on  its  antero-internal  aspect  just  below  the  neck,  an  oval  eminence, 
called  the  bicipital  tuberosity.  This  is  divided  vertically  into  two 
parts,  a  rough  posterior  portion  which  gives  insertion  to  the  tendon 
of  the  biceps,  and  a  smooth  anterior  part  which  is  separated  from 
that  tendon  by  a  bursa.  Below  the  bicipital  tuberosity  the  shaft 
presents  three  borders  and  three  surfaces.  The  anterior  border 
extends  from  the  lower  and  anterior  part  of  the  bicipital  tuberosity 
to  the  anterior  border  of  the  styloid  process.  In  its  upper  third 
it  crosses  the  shaft  obliquely  downwards  and  outwards,  this  portion 
of  it  being  called  the  anterior  oblique  line.  This  line  limits  ex- 
ternally the  insertion  of  the  supinator  radii  brevis,  and  internally 
the  origin  of  the  flexor  longus  pollicis,  whilst  its  prominent  edge 
gives  origin  to  the  thin  radial  portion  of  the  flexor  sublimis 
digitorum.  The  internal  or  interosseous  border  commences  at  the 
lower  and  back  part  of  the  bicipital  tuberosity,  and  near  the  lower 
extremity  of  the   shaft  it  divides  into  two  ridges,  which  pass  to 


THE  BONES  OF  THE   UPPER  LIMB 


175 


Head  of  Radius 


Neck 


Posterior  part  of  Bicipital  - 

Tuberosity  and  Tendon 

of  Biceps 

Supinator  Radii  Brevis 


Anterior  Oblique  Line   - 
Flexor  Sublimis  Digitorum  -  - 

Medullarj-  Foramen  — 

Flexor  Longus  Pollicis   - 
Pronator  Radii  Teres  — 

Anterior  Border  — 


r 


.  Olecranon  Process 

^  Great  Sigmoid  Cavity 

_  Coronoid  Process 

—  Flexor  Sublimis  Digitorum 

"Deep  Head  of  Pronator 
Radii  Teres 

Brachialis  Anticus 

—Supinator  Radii  Brevis 


Medullary  Foramen 

-  Anterior  Border 

.  Flexor  Profundus  Digitorum 


Pronator  Quadratus If. 


_.  Pronator  (Juadratus 


Brachio-radialis 


Head 

Styloid  Process  of  Ulni. 


Styloid  Process  of  Radius 

Fig.   103.— The  Right  Radius  and  Ulna  (Anterior  View). 


176  A  MANUAL  OF  ANATOMY 

the  anterior  and  posterior  margins  of  the  sigmoid  cavity.  At  its 
commencement  it  is  round  and  indistinct,  and  immediately  below 
the  bicipital  tuberosity  it  gives  attachment  to  the  oblique  ligament. 
Over  the  rest  of  its  extent  it  is  sharp  and  wiry  for  the  attachment 
of  the  interosseous  membrane,  which  is  also  connected  with  the 
posterior  of  the  two  lower  divisions.  The  posterior  border  extends 
from  the  back  of  the  bicipital  tuberosity  to  the  prominent  radial 
tubercle  about  the  centre  of  the  posterior  border  of  the  lower 
extremity.  In  its  upper  third  it  crosses  the  shaft  obliquely  down- 
wards and  outwards,  this  portion  of  it,  which  is  prominent,  being 
called  the  posterior  oblique  line.  This  line  limits  the  insertion  of 
the  supinator  radii  brevis  above,  and  the  origin  of  the  extensor 
ossis  metacarpi  pollicis  below. 

The  anterior  surface  is  situated  between  the  anterior  and  internal 
or  interosseous  borders.  In  the  upper  two-thirds  it  is  concave, 
and  gives  origin  to  the  flexor  longus  pollicis.  In  the  lower 
third  it  is  flat  and  expanded,  and  this  portion  gives  insertion 
to  the  pronator  quadratus,  except  close  to  the  anterior  border  of 
the  lower  extremity,  where  it  gives  attachment  to  the  anterior 
ligament  of  the  wrist-joint.  The  anterior  surface  presents  the 
medullary  foramen  about  the  junction  of  the  upper  and  middle 
thirds.  The  direction  of  the  canal  to  which  it  leads  is  upwards, 
and  it  gives  passage  to  the  medullary  branch  of  the  anterior  inter- 
osseous artery.  The  portion  of  bone  between  the  anterior  oblique 
line,  the  lower  part  of  the  front  of  the  neck,  and  the  bicipital  tuber- 
osity gives  insertion  to  a  portion  of  the  supinator  radii  brevis. 
The  external  surface  is  situated  between  the  anterior  and  posterior 
borders.  It  is  convex  from  above  downwards,  and  from  side  to 
side.  In  its  upper  third  it  gives  insertion  to  the  supinator  radii 
brevis ;  at  its  centre  there  is  a  rough  impression,  fully  an  inch 
long,  for  the  insertion  of  the  pronator  radii  teres ;  and  below  this 
it  supports  the  tendons  of  the  extensores  carpi  radialis  longior 
et  brevior,  and  is  crossed  obliquely  by  the  tendons  of  the  extensor 
ossis  metacarpi  pollicis  and  extensor  brevis  pollicis  (primi  internodii 
pollicis).  The  external  surface  also  supports  the  brachio-radialis, 
which  is  inserted  into  its  lower  extremity  close  to  the  base  of  the 
styloid  process.  The  posterior  surface  is  situated  between  the 
posterior  and  internal  or  interosseous  borders.  Above  the  posterior 
oblique  line  it  is  covered  by  the  supinator  radii  brevis,  which  takes 
insertion  into  its  outer  half.  Below  the  posterior  oblique  line  it 
is  concave  over  about  the  middle  third,  where  it  gives  origin  from 
above  downwards  to  the  extensor  ossis  metacarpi  pollicis  and 
extensor  brevis  pollicis.  The  lower  third  is  broad  and  convex, 
and  it  supports  the  tendons  of  the  extensor  longus  pollicis,  extensor 
communis  digitorum,  and  extensor  indicis. 

The  lower  extremity  is  large  and  pentagonal,  as  viewed  from 
below.  Externally  it  presents  the  styloid  process,  internally  the 
sigmoid  cavity,  and  inferiorly  the  carpal  articular  su  rface,  the  latter 
two  being  covered  by  cartilage.     The  styloid  process  projects  down- 


THE  BONES  OF  THE  UPPER  LIMB 


Head 


Neck 


.  Bicipital  Tuberosity 
•  Supinator  Radii  Brevis 

Posterior  Oblique  Line 


177 


'\        1   tIS Extensor  Ossis  Metacarpi  Pollicis 

-  Internal  or  Interosseus  Border 
Pronator  Radii  Teres 


.  Extensor  Brevis  Pollicis 
Posterior  Border 


i;f. 


Extensor  Communis 
iJigitorum  and  Extensor  Indicis 


Poll 


Brachio-radialis 


_  Tip  of  Styloid  Process 


Extensor  I-onj4 

Radial  'lubercle       j      | 
Extensor  Carpi  Kadialis  Brevior      | 

Extensor  Carpi  Radialis  Lotinior 

Fig.   104.— The  liu.nr   Rauids  (Posterior  Surface), 


12 


178  A  MANUAL  OF  ANATOMY 

wards  as  a  stout  conical  process,  terminating  in  a  round  tip  which 
gives  attachment  to  the  external  lateral  ligament  of  the  wrist-joint. 
The  inner  surface  is  covered  by  the  cartilage  of  the  carpal  articular 
surface.  The  outer  surface  presents  a  groove  directed  downwards 
and  slightly  forwards,  and  subdivided  into  two  compartments,  the 
outer  of  which  transmits  the  tendon  of  the  extensor  ossis  metacarpi 
poUicis,  and  the  inner  that  of  the  extensor  brevis  pollicis.  This 
groove  is  separated  from  the  pronator  surface  in  front  by  a  promi- 
nent ridge  which  gives  attachment  to  the  posterior  annular  ligament. 
The  anterior  surface  supports  a  portion  of  the  radial  artery. 

The  sigmoid  cavity  is  concave  from  before  backwards,  and  articu- 
lates with  the  outer  convex  surface  of  the  head  of  the  ulna. 

The  carpal  articular  surface  is  of  large  size,  and  its  plane  is 
oblique,  being  sloped  outwards  and  a  little  downwards.  It  is 
concave  from  before  backwards,  and  from  side  to  side,  and  is 
divided  into  two  parts  by  an  antero-posterior  elevation.  The 
outer  division  is  triangular,  its  cartilage  being  prolonged  on  to 
the  inner  surface  of  the  styloid  process,  and  it  articulates  with 
the  scaphoid  bone.  The  inner  division  is  quadrilateral,  and 
articiilates  with  the  semilunar  bone.  It  is  separated  from  the 
sigmoid  cavity  by  a  sharp  concave  margin,  which  gives  attach- 
ment to  the  base  of  the  triangular  interarticular  fibro-cartilage. 
Immediately  above  the  anterior  border  there  is  a  rough  sur- 
face for  the  attachment  of  the  anterior  ligament  of  the  wrist- 
joint.  The  posterior  border  is  on  a  slightly  lower  level  than  the 
anterior,  and  is  irregularly  convex.  It  presents  about  its  centre 
a  prominent  elevation,  called  the  radial  tubercle,  and  is  divided 
into  three  grooves — outer,  middle,  and  inner.  The  outer  groove, 
which  is  broad,  is  bounded  externally  by  a  ridge  which  separates 
it  from  the  groove  on  the  outer  surface  of  the  styloid  process, 
and  internally  by  the  radial  tubercle.  It  is  usually  subdivided 
by  a  faint  line  into  two  compartments,  the  outer  of  which  transmits 
the  tendon  of  the  extensor  carpi  radialis  longior,  and  the  inner 
that  of  the  extensor  carpi  radialis  brevior.  The  middle  groove, 
narrow  and  deep,  is  directed  from  above  downwards  and  outwards, 
and  is  bounded  externally  by  the  radial  tubercle,  which  slightly 
overhangs  it,  and  internally  by  an  oblique  ridge  separating  it  from 
the  inner  groove.  It  transmits  the  tendon  of  the  extensor  longus 
pollicis  (secundi  internodii  pollicis).  The  inner  groove  is  single, 
and  transmits  the  tendons  of  the  extensor  communis  digitorum 
and  extensor  indicis.  It  is  separated  from  the  sigmoid  cavity  by 
a  sharp  ridge  which,  with  the  ulna  in  position,  bounds  a  groove  for 
the  tendon  of  the  extensor  minimi  digiti.  The  ridges  separating 
the  grooves  give  attachment  to  deep  expansions  of  the  posterior 
anmilar  ligament,  which,  with  the  ligament,  convert  the  grooves 
into  fibro-osseous  canals. 

The  lower  extremity  presents  several  nutrient  foramina  for 
branches  of  the  anterior  and  posterior  interosseous  arteries,  and 
anterior  and  posterior  carpal  arches. 


THE  BONES  OF  THE  UPPER  LIMB 


179 


Articulations. — Superiorly  with  the  capitellum  of  the  humerus 
and  small  sigmoid  cavity  of  the  ulna,  and  inferiorly  with  the  head 
of  the  ulna,  scaphoid,  and  semilunar. 


For  Posterior  Ligament 


Groove  for  Ext.  Longus  Pollicis 

Radial  Tubercle     1 

Groove  for  Ext.  Carpi  Rad.  Brev.        I     1 

Groove  for  Ext.  Carpi 

Radialis  Longior 


Groove   for   Ext.    Oss. 

Metacarp.     Poll,    and ' 

Ext.  Brev.  Pollicis 


Groove  for  Ext.  Com.  Dig.  and  Ext.  Indicis 
I  Groove  for  Ext.  Minimi  Digiti 

I  I 

Groove  for  Ext.  Carpi  Ulnaris 
Ulnar  Styloid  Process 


For  Scaphoid  | 

For  Anterior  Ligament 


For  Apex  of  Triangular 
\  Fibro-Cartilage 

For  Upper  Surface  of  Triangular 
For  Semilunar  Fibro-Cartilage 


Fig.  10^ 


-The  Lower  Ends  of  the  Left  Radius  and  Ulna 
AS  seen  from  below  in  Pronation. 

(The  Dorsal  Aspect  is  upwards.) 


Structure. — This  is  similar  to  that  of  long  bones.  At  the  lower 
extremity  the  cancellated  tissue  extends  upwards  for  about  i|  inches 
above  the  styloid  process,  this  level  being  the  site  of  Colles'  fracture. 

Ossification. — The  radius  ossifies  in  cartilage  from  one  primary,  and  two 
secondary,  centres.  The  primary  centre  appears  at  the  middle  of  the  shaft  in 
the  eighth  week  of  intra-uterine  life.  At  birth  the  shaft  is  ossified,  but  the 
extremities  are  cartilaginous.  The  secondary  centre  for  the  lower  extremity 
appears  in  the   second  year,  and   that  for  the  head  in  the  fifth  year.     The 


n 


..Appears  in  the  5th  Year, 
and  joins  about  iS 


.  Appears  in  the  8th  Week 
(intra-uterine) 


I      Appears  in  the  2nd  Year, 
and  joins  about  20 

Fig.  io6.-^Ossification  of  the  Radius. 

upper  epiphysis  joins  the  shaft  about  the  eighteenth  year,  and  the  lower 
epiphysis  about  tlie  twentieth  year.  Sometimes  the  surface  of  the  bicipital 
tuberosity  forms  an  epiphysis,  in  which  cases  there  is  a  special  secondary  centre 
for  it,  appearing  aljout  the  fourteenth  year,  and  joining  the  rest  of  the  shaft 
very  soon  thereafter. 

12 — 2 


i8o  A  MANUAL  OF  ANATOMY 

The  Ulna. 

The  ulna  is  the  internal  bone  of  the  forearm  (which  is  assumed 
to  be  in  a  position  of  supination).  It  is  parallel  with,  and  longer 
than,  the  radius,  and  extends  from  the  elbow  to  the  wrist,  being 
separated  from  the  latter  joint  by  the  triangular  interarticular 
fibro-cartilage.  It  is  a  long  bone,  and  is  divisible  into  a  shaft  and 
two  extremities,  the  upper  of  which  is  of  large  size. 

The  upper  extremity  presents  the  olecranon  and  coronoid  processes, 
and  the  great  and  small  sigmoid  cavities.  The  olecranon  process 
forms  the  highest  part  of  the  bone,  and  is  curved  forwards  at  its  upper 
part.  It  is  largely  subcutaneous.  Superiorly  it  presents  a  broad,  flat, 
quadrilateral  surface,  at  the  back  part  of  which  is  a  rough  elevation 
for  the  insertion  of  the  triceps.  In  front  of  this  there  is  a  smooth 
area  where  a  bursa  intervenes  between  that  muscle  and  the  bone. 
At  its  anterior  part,  near  the  anterior  margin,  there  is  a  narrow 
transverse  impression  for  part  of  the  posterior  ligament  of  the 
elbow- joint.  The  superior  surface  is  limited  anteriorly  by  a 
sharp  convex  border,  projected  at  its  centre  into  a  process,  called 
the  heak,  which  overhangs  the  upper  part  of  the  great  sigmoid 
cavity,  and  is  received  into  the  olecranon  fossa  of  the  humerus 
in  extension  of  the  joint.  The  anterior  surface  is  directed  down- 
wards and  forwards,  and  forms  the  upper  part  of  the  great  sigmoid 
cavity.  The  posterior  surface,  smooth,  flat,  and  triangular,  is 
subcutaneous,  and  covered  by  a  bursa.  The  inner  surface  pre- 
sents a  tubercle  for  the  ulnar  head  of  the  flexor  carpi  ulnaris,  and 
the  inner  border  gives  attachment  to  the  posterior  part  of  the 
internal  lateral  ligament  of  the  elbow- joint.  The  outer  surface 
gives  insertion  to  a  portion  of  the  anconeus,  and  the  outer  border 
gives  attachment  to  fibres  of  the  posterior  ligament  of  the  joint. 

The  coronoid  process  is  triangular,  and  projects  forwards.  The 
superior  surface  forms  the  lower  and  anterior  part  of  the  great 
sigmoid  cavity.  The  inferior  surface  is  rough  and  concave,  and  the 
roughness  is  prolonged  upon  the  anterior  surface  of  the  shaft  for 
about  an  inch,  giving  rise  to  a  triangular  impression,  the  inner  half  of 
which  gives  insertion  to  the  brachialis  anticus.  The  upper  part 
of  this  surface,  close  to  the  anterior  border  of  the  process,  affords 
attachment  to  the  anterior  ligament  of  the  elbow-joint.  The 
lower  pointed  portion  presents  externally  a  rough  prominence, 
called  the  tuberosity,  which  gives  insertion  to  fibres  of  the  brachialis 
anticus,  and  attachment  to  the  oblique  ligament.  The  anterior 
margin  is  sharp,  convex,  and  curved  slightly  upwards,  and  it  is 
projected  at  its  outer  part  into  a  process,  called  the  heak,  which  is 
received  into  the  coronoid  fossa  of  the  humerus  in  flexion  of  the 
elbow-joint.  The  inner  border  gives  attachment  to  the  anterior 
portion  of  the  internal  lateral  ligament,  and  at  its  upper  part  it 
presents  a  tubercle  for  the  ulnar  head  of  the  flexor  sublimis  digi- 
torum.  Leading  downwards  from  this  there  is  a  short  ridge  for 
the  origin  of  the  deep  head  of  the  pronator  radii  teres,  below  which 


THE  BONES  OF  THE   UPPER  LIMB 


i8i 


a  slip  of  the  flexor  longus  pollicis 
sometimes  arises.  Behind  the 
flexor  subHmis  tubercle  there  is 
a  depressed  surface  which  gives 
origin  to  the  highest  fibres  of 
the  flexor  profundus  digitorum. 
The  outer  surface  presents  the 
small  sigmoid  cavity. 

The  great  sigmoid  cavity,  which 
articulates  with  the  trochlea  of 
the  humerus,  when  viewed  from 
the  side,  forms  half  a  circle. 
The  upper  half  of  the  cavity  is 
formed  by  the  anterior  surface 
of  the  olecranon  process,  and  the 
lower  half  by  the  upper  surface 
of  the  coronoid  process.  It  is 
constricted  at  the  centre  by  a 
notch  at  either  side,  which  marks 
the  meeting  of  the  olecranon 
and  coronoid  processes,  the  inner 
notch  being  bridged  over  by  a 
fibrous  band  with  which  the 
middle  part  of  the  internal  lateral 
ligament  blends.  The  cartilage 
of  the  cavity  is  sometimes  broken 
up  at  this  part  by  a  narrow,  rough, 
transverse  interval.  Extending 
from  the  beak  of  the  olecranon 
to  the  beak  of  the  coronoid  there 
is  a  longitudinal  elevation,  which 
divides  the  cavity  into  two  lateral 
halves,  the  inner  being  concave 
from  side  to  side,  and  the  outer 
convex. 

The  small  sigmoid  cavity, which 
is  situated  on  the  outer  surface  of 
the  coronoid  process,  is  concave 
from  before  backwards,  and  ar- 
ticulates with  the  inner  aspect 
of  the  head  of  the  radius.  Its 
anterior  and  posterior  margins 
give  attachment  to  the  cornua  of 
the  orbicular  ligament. 

The  upper  extremity  presents 
several  nutrient  foramina  for 
branches  of  the  anterior  and 
posterior  ulnar  recurrent  and 
interosseous  recurrent  arteries. 


^— "Beak  of  Olecranon  Process 

-Great  Sigmoid  Cavity 
•P"or  Olecranon  Bursa 

-Beak  of  Coronoid  Process 


-Small  Sigmoid  Cavity 
^-  —  Anconeus 

Supinator  Radii  Brevis 


Oblique  Line 

,-*. Extensor  Ossis  Metacarpi  Pollicis 

Posterior  Border 

Extensor  Longus  Pollicis 

—  External  or  Interosseous  Border 

Extensor  Indicis 


-For  Sigmoid  Cavity  of  Radius 

Head 
^>     Groove  for  Kxlensor  Gariji  Uln.iris 

.Styloid  Process 

Fig.    107. — Thk  "Right  Ulna 
(Posterior  SuRFACii). 


i82  A  MANUAL  OF  ANATOMY 

The  shaft  diminishes  in  size  from  above  downwards,  and  is 
triangular  in  its  upper  three-fourths,  where  it  is  slightly  curved 
with  the  convexity  directed  backwards.  In  the  lower  fourth  it 
is  slender  and  subcylindrical,  being  flattened  in  front.  It  presents 
three  borders  and  three  surfaces.  The  anterior  border  extends 
from  the  flexor  sublimis  tubercle  on  the  inner  margin  of  the 
coronoid  process  to  the  front  of  the  styloid  process.  Over  its 
upper  three-fourths  it  is  round,  and  gives  origin  to  fibres  of  the 
flexor  profundus  digitorum.  Over  its  lower  fourth  it  is  sharp, 
and  gives  origin  to  the  pronator  quadratus.  The  posterior  border, 
which  is  subcutaneous,  extends  from  the  apex  of  the  triangular 
subcutaneous  surface  on  the  back  of  the  olecranon  to  the  back  of 
the  styloid  process.  Over  its  upper  two- thirds  it  gives  attachment 
to  a  strong  aponeurosis,  which  gives  common  origin  to  the  flexor, 
and  extensor,  carpi  ulnaris,  and  flexor  profundus  digitorum.  The 
external  or  interosseous  border  extends  from  the  apex  of  the  bicipital 
hollow,  about  two  inches  below  the  small  sigmoid  cavity,  to  the 
outer  aspect  of  the  head.  Over  the  middle  three-fifths  of  the 
shaft  it  is  sharp  and  prominent,  but  over  the  lower  fifth  it  is  very 
faint.     It  gives  attachment  to  the  interosseous  membrane. 

The  anterior  surface  is  situated  between  the  anterior  and  inter- 
osseous borders.  It  is  concave  over  its  upper  three-fourths,  and 
gives  origin  to  part  of  the  flexor  profundus  digitorum.  The 
lower  fourth  is  flat,  and  gives  origin  to  the  pronator  quadratus. 
This  surface  presents  the  medullary  foramen  a  little  above  the 
centre,  the  direction  of  the  canal  to  which  it  leads  being  upwards. 
It  gives  passage  to  the  medullary  branch  of  the  anterior  inter- 
osseous artery.  The  internal  surface  is  situated  between  the 
anterior  and  posterior  borders.  Over  its  upper  two-thirds  it 
gives  origin  to  part  of  the  flexor  profundus  digitorum,  the  lower 
portion  being  subcutaneous.  The  posterior  surface  is  situated 
between  the  posterior  and  interosseous  borders,  and  is  directed 
backwards  and  outwards.  It  presents  superiorly  the  oblique  line, 
which  extends  from  the  supinator  ridge  on  the  posterior  margin 
of  the  bicipital  hollow  to  the  posterior  border  at  the  junction  of 
the  upper  and  middle  thirds.  The  triangular  portion  above  this 
line  is  called  the  anconeal  surface,  which  extends  over  the  outer 
surface  of  the  olecranon.  It  gives  insertion  to  the  anconeus.  The 
posterior  surface,  below  the  oblique  line,  is  divided  into  two  lateral 
parts  by  a  vertical  ridge.  The  inner  portion  supports  the  extensor 
carpi  ulnaris,  and  the  outer  gives  origin,  from  above  downwards,  to 
the  extensor  ossis  metacarpi  poUicis,  extensor  longus  pollicis,  and 
extensor  indicis.  On  the  outer  aspect  of  the  shaft  superiorly  there 
is  a  triangular  depression,  called  the  bicipital  hollow,  which  com- 
mences immediately  below  the  small  sigmoid  cavity,  and  extends 
downwards  for  about  2  inches.  It  is  bounded  in  front  and  behind 
by  prominent  lips,  the  anterior  of  which  passes  above  into  the  outer 
margin  of  the  coronoid  process,  and  the  posterior  into  the  posterior 
margin  of  the  small  sigmoid  cavity.     The  upper  part  of  the  posterior 


THE  BONES  OF  THE  UPPER  LIMB 


183 


lip,  which  is  prominent,  is  called  the  supinator  ridge,  and  it  gives 
origin  to  a  part  of  the  supinator  radii  brevis.  The  two  lips  form 
by  their  meeting  the  commencement  of  the  external  or  interosseous 
border.  The  anterior  part  of  the  bicipital  hollow  receives  the 
bicipital  tuberosity  of  the  radius,  with  the  tendon  of  insertion  of 
the  biceps,  in  pronation,  whilst  the  posterior  part  gives  origin  to 
fibres  of  the  supinator  radii  brevis. 

The  lower  extremity  is  small,  and  presents  a  head  and  styloid 
process.  These  are  separated  behind  by  a  groove  for  the  tendon 
of  the  extensor  carpi  ulnaris,  and  below  by  a  rough  pit  which  gives 
attachment  to  the  apex  of  the  triangular  interarticular  fibro-cartilage. 
The  outer  aspect  of  the  head  is  convex,  and  covered  by  cartilage  for 
articiilation  with  the  sigmoid  cavity  of  the  radius,  a  portion  of 
the  synovial  membrane,  called  memhrana  sacciformis,  intervening. 
The  inferior  surface,  also  covered  by  cartilage,  is  flat,  and  is 
related  to  the  upper  surface  of  the  triangular  interarticular  fibro- 
cartilage,  with  the  intervention  of  another  portion  ^of  the  mem- 
brana  sacciformis. 

The  styloid  process,  of  small  size  and  subcutaneous,  projects 
downwards  from  the  posterior  and  inner  part  of  the  head  (mainly 
from  the  back  part),  and  it  terminates  in  a  round  tip  which 
gives  attachment  to  the  internal  lateral  ligament  of  the  wrist- 
joint. 

The  lower  extremity  presents  several 
branches  of  the  anterior  and  posterior 
interosseous  arteries. 

Articulations.  —  Superiorly  with  the 
trochlea  of  the  humerus,  and  the  inner 
aspect  of  the  head  of  the  radius  ;  inferiorly 
with  the  sigmoid  cavity  of  the  radius,  and 
the  triangular  interarticular  fibro-cartilage, 
the  latter  structure  separating  it  from  the 
cuneiform  or  pyramidal  bone. 

Structure. — This  is  similar  to  that  of 
long  bones. 

Ossification. — The  ulna  ossifies  in  cartilage  from 
one  primary,  and  two  secondary,  centres.  The 
primary  centre  appears  at  the  middle  of  the 
shaft  in  the  eighth  week,  and  from  it  the  shaft, 
coronoid  process,  and  greater  part  of  the  olecra- 
non process  are  ossified.  At  birth  the  shaft  and 
coronoid  process  are  ossified,  but  the  greater  part 
of  the  olecranon  and  the  lower  extremity  are 
cartilaginous.  The  secondary  centre  for  the  lower 
extremity  appears  in  the  fourth  year,  and  from  it 
the  head  and  styloid  process  are  ossified.     The 

secondary  centre  for  the  upper  extremity  appears  in  the  tenth  year,  and  may 
involve  only  a  thin  scale  on  the  summit  of  the  olecranon  process,  or  it  may 
afford  ossification  to  a  third,  or  even  a  half,  of  that  process.  The  upper 
epiphysis  joins  about  the  sixteenth  year,  and  the  lower  al)Out  the  twentieth 
year. 


nutrient    foramina   for 


Appears  in  the  loth  Year, 
and  joins  about  16 


Appears  in  the  Sth  Week 
(iiitra-uterine) 


Fig, 


Appears  in  the  4th  Year, 
and  joins  about  20 

108. — Ossification 
OF  THE  Ulna. 


i84  A  MANUAL  OF  ANATOMY 

The  Carpus. 

The  carpus  or  wrist  is  composed  of  eight  short  bones,  which  are 
arranged  in  two  rows,  there  being  four  bones  in  each  row.  The  rows 
are  called  first  or  proximal,  and  second  or  distal.  The  bones  of  the 
first  row,  from  without  inwards,  are  called  scaphoid,  semilunar, 
cuneiform,  and  pisiform,  whilst  those  of  the  second  row,  in  a  similar 
order,  are  named  trapezium,  trapezoid,  os  magnum,  and  unciform. 

The  Scaphoid  Bone. 

The  scaphoid  bone,  which  is  characterized  by  its  boat-like  shape, 
lies  with  its  long  axis  oblique,  the  broad  end  being  directed  upwards 
and  inwards,  and  the  narrow  end  or  prow  downwards,  outwards 
and  forwards.  S%i.periorly  it  presents  a  convex  articular  surface 
for  the  radius,  which  encroaches  on  the  dorsal  aspect.  Inferiorly 
it  also  presents  a  convex  articular  surface  directed  downwards,  out- 


A 

Superior  Surface  for  Radius 


Tuberosity 

1  For  Semilunar 


]5!>l(Sffll I ||Ill^^^MP^  N^i^^^™ffl*^^       For  Os  Magnum 

Posterior  Surface'     ^"J^ijiS^^*'^ 

Inferior  Surface  for  Trapezium 
and  Trapezoid 

Fig.    109. — The    Right    Scaphoid    Bone. 
A,  Posterior  View  ;    B,   Internal  View. 

wards,  and  backwards,  which  likewise  encroaches  on  the  dorsal 
aspect,  and  is  divisible  into  two  parts — an  outer  for  the  trapezium, 
and  an  inner  for  the  trapezoid.  The  internal  surface  presents  two 
articular  facets — a  superior,  crescentic,  narrow  from  above  down- 
wards, and  looking  inwards,  for  the  semilunar,  and  an  inferior, 
large,  concave,  and  directed  downwards  as  well  as  inwards,  for 
the  outer  side  of  the  head  of  the  os  magnum.  The  external  aspect 
takes  the  form  of  a  rough  border,  extending  from  the  radial  surface 
to  the  tuberosity,  and  giving  attachment  to  the  external  lateral 
ligament  of  the  wrist-joint.  At  its  lower  end  there  is  a  prominent 
tuberosity,  directed  forwards,  which  gives  attachment  to  fibres  of  the 
anterior  annular  ligament  and  abductor  pollicis.  The  palmar  surface 
is  rough  and  triangular.  The  dorsal  s^trface,  being  encroached  upon 
by  the  superior  and  inferior  convex  articular  surfaces,  is  reduced 
to  a  rough  oblique  groove. 

Articulations. — Superiorly  with  the  radius,  inferiorly  with  the 
trapezium  and  trapezoid,  and  internally  with  the  semilunar  and  os 
magnum. 


THE  BONES  OF  THE  UPPER  LIMB  185 

The  Semilunar  Bone. 

The  semilunar  or  lunar  bone  is  characterized  by  the  crescentic 
concavity  on  its  inferior  surface.  Superiorly  it  presents  a  quadri- 
lateral, convex,  articular  surface  for  the  radius,  which  encroaches 
on  the  dorsal  aspect.  The  inferior  surface  is  deeply  concave  from 
before  backwards.  The  greater  part  of  it  articulates  with  the  upper 
surface  of  the  head  of  the  os  magnum,  and  the  narrow  inner  strip 
with   the   upper   border   of   the   unciform.     The   external   surface, 

A  B 

Superior  Surface  for  Radius 
Internal  Surface  for  Cuneiform 
For  Unciform  (011^ 

Inferior  Surface)     ^Vi     r  m    '  >     1  -^  jn.  »         r.  1         c-     r 

Palmar  Surface.      /  ^4  1/  \    /        ^r,'i;;r?l§fi        Palmar  Surface 


Inferior  Surface  for  Os  Magnum  For  Scaphoid  (on  External  Surface) 

Fig.   1 10. — The  Right  Semilunar  Bone. 
A,    Internal   View  ;    B,    Supero-external    View. 

narrow  from  above  downwards,  presents  a  crescentic  facet  for  the 
scaphoid.  The  internal  surface,  which  is  inclined  downwards 
and  outwards,  is  deep  from  above  downwards,  and  presents 
a  semi-oval  facet  for  the  cuneiform.  The  palmar  and  dorsal 
surfaces  are  rough,  the  former  being  large,  convex,  and  quadri- 
lateral, and  the  latter  small  and  flat. 

Articulations. — Superiorly  with  the  radius,  inferiorly  with  the  os 
magnum  and  unciform,  externally  with  the  scaplioid,  and  internally 
with  the  cuneiform. 


The  Cuneiform  Bone. 

The  cuneiform  or  pyramidal  bone  is  characterized  by  its  resem- 
blance to  a  wedge,  or  j)yramid,  and  it  lies  obliquely  with  the  base 

.Inferior  Surface  for  Unciform 


External  Surface  for  Semilunar 


For  Pisiform  Anterior  Surface 

(on  Anterior  Surface) 

Fig.  III. — The  Right  Cuneiform  or  Pyramidal  Bone 
(Anterior.  External,  and  Inferior  Surfaces). 

directed    outwards    and    ujnvards.     The    external    surface,    which 
corresponds  with  the  base,  presents  a  semi-oval  facet  for  the  semi- 


i86  A  MANUAL  OF  ANATOMY 

lunar.  The  internal  surface,  which  represents  the  rounded  apex, 
is  of  Hmited  extent,  and  rough  for  the  internal  lateral  hgament  of 
the  wrist- joint.  The  palmar  surface  presents  a  circular,  shghtly 
convex  facet,  which  occupies  rather  more  than  the  inner  and 
lower  half,  and  articulates  with  the  pisiform,  the  rest  of  the  surface 
being  rough.  The  sup ero -posterior  surface  is  divisible  into  two  parts, 
outer  and  inner.  The  outer  portion,  which  is  close  to  the  base, 
presents  a  convex  facet  for  the  inferior  surface  of  the  triangular 
interarticular  fibro-cartilage.  The  inner  portion  is  marked  by  two 
rough  oblique  grooves,  superior  and  posterior,  separated  by  a  ridge 
which  is  dorsally  placed.  The  inferior  surface  presents  a  large 
triangular  facet,  concavo-convex  from  without  inwards,  for  the 
unciform. 

Articulations. — Superiorly  with  the  triangular  interarticular 
fibro-cartilage,  inferiorly  with  the  unciform,  externally  with  the  semi- 
lunar, and  anteriorly  with  the  pisiform. 

The  Pisiform  Bone. 

The  pisiform  bone  is  characterized  by  its  resemblance  to  a  pea, 
and  is  placed  in  front  of  the  cuneiform,  which  constitutes  its  only 
articulation.  It  is  irregularly  round,  except  posteriorly,  where  it 
presents  over  its  upper  three-fourths  a  circular,  slightly  concave 
facet  for  the  cuneiform,  the  lower  fourth  being  non-articular.     The 

Superior  Aspect 


-Ulnar  Groove 
(on  External  Surface) 

For  Cuneiform 

(on  Posterior  Surface) 

Fig.   112. — The  Right  Pisiform  Bone  (Postero-external  View). 

long  axis  of  the  bone  is  directed  downwards  and  slightly  outwards. 
The  palmar  surface  gives  attachment  superiorly  to  the  flexor  carpi 
ulnaris,  inferiorly  to  the  pisi-uncinate  and  pisi-metacarpal  ligaments, 
and  abductor  minimi  digiti,  and  externally  to  a  portion  of  the 
anterior  annular  Hgament.  The  internal  surface  is  irregularly 
convex,  and  the  external  presents  the  ulnar  groove,  which  lodges 
the  ulnar  nerve  and  artery. 

The  Trapezium. 

The  trapezium  is  the  external  bone  of  the  second  row,  and  is 
characterized  by  a  groove  and  ridge  on  its  palmar  surface,  and  a 
saddle-shaped    facet    on    its    inferior    surface.      It    is    polyhedral. 


THE  BONES  OF  THE   UPPER  LIMB 


187 


and  its  long  axis  is  directed  downwards  and  inwards.  The 
superior  surface  presents  a  semi-oval,  concave  facet  for  the 
scaphoid.  The  inferior  surface  presents  a  saddle-shaped  facet, 
concave  from  side  to  side,  convex  from  before  backwards,  and 
directed  outwards  as  well  as  downwards,  for  the  base  of  the  first 
metacarpal  bone.  The  internal  surface  has  two  facets — an  upper, 
which  is  large  and  concave,  for  the  trapezoid,  and  a  lower,  which  is 
small,  for  the  base  of  the  second  metacarpal  bone.  The  external 
surface  is  broad,  pentagonal,  and  rough.  The  palmar  surface, 
rough  and  elongated  from  above  downwards  and  inwards,  is  broad 
above  and  narrow  below.  Superiorly  it  presents  a  deep  groove, 
directed  downwards  and  inwards,  which  transmits  the  tendon  of 
the  flexor  carpi  radialis,  and  external  to  this  groove  a  prominent 
ridge,  called  the  tuberosity,  which  gives  attachment  to  the  anterior 
annular  ligament,  abductor  pollicis,   and  opponens  poUicis.     The 


Tuberosity 


A 

Groove  for  Flexor 
Carpi  Radialis 


Inferior  Surface 
for  ist  Metacarpal. 


For  Scaphoid 
'  (on  Superior  Surface) 


"For  Trapezoid 

(on  Internal  Surface) 


For  2nd  Metacarpal 
(on  Internal  Surface) 


For  2nd  Metacarpal 

Fig.   113. — The  Right  Trapezium. 
A,  Antero-inferior  View  ;  B,  Supero-internal  View. 

dorsal  surface  is  broader  than  the  palmar,  and  its  inferior  and 
internal  angle  is  much  elongated  towards  the  base  of  the  second 
metacarpal  bone,  with  which  it  articulates  by  the  small  facet  on 
its  inner  aspect. 

Articulations. — Superiorly  with  the  scaphoid,  inferiorly  with  the 
first  metacarpal,  and  internally  chiefly  with  the  trapezoid,  but  also 
with  the  second  metacarpal. 


The  Trapezoid  Bone. 

The  trapezoid  bone  somewhat  resembles  the  trapezium,  but  it  is 
destitute  of  a  grcjove  and  tuberosity.  Its  antero-postcrior  diameter 
is  longer  than  the  transverse.  The  palmar  surface  is  small  and 
pentagonal,  and  it  gives  origin  to  fibres  of  the  adductor  obliquus 
jwllicis.  The  dorsal  surface  is  large  and  has  its  internal  and  inferior 
angle  elongated  towards   the  styloid  process  of  the  third  meta- 


isa 


A   MANUAL  OF  ANATOMY 


carpal  bone.  Both  of  these  surfaces  are  rough  for  ligaments. 
The  superior  surface  presents  a  quadrilateral,  concave  facet,  elon- 
gated from  before  backwards,  for  the  scaphoid.  The  inferior 
surface  is  characterized  by  a  large  saddle-shaped  facet,  convex 
from  side  to  side  and  concave  from  before  backwards,  for  the  base 
of  the  second  metacarpal  bone.  The  external  stcrface  has  a  convex 
facet  for  the  trapezium,  below  which  there  is  a  rough  triangular 
surface  with  the  base  directed  anteriorly.  The  internal  surface  is 
concave  from  before  backwards,  and  its  anterior  portion  presents 
a  facet  for  the  os  magnum. 


For  Trapezium 
(on  External  Surface) 


Dorsal  Surface 


Superior  Surface 
for  Scaphoid 


, -.External  Surface 


^^  Part  of  Inferior  Surface 
for  2nd  Metacarpal 


Part  of  Inferior  Surface 
for  2nd  Metacarpal 

--Internal  Surface 
for  Os  Magnum 


'—.'Dorsal  Surface 


Fig.  114. — The    Right    Trapezoid    Bone. 
A,  External  View ;  B,  Posterior  View. 


Articulations. — Superiorly  with  the  scaphoid,  inferiorly  with  the 
second  metacarpal,  externally  with  the  trapezium,  and  internally 
with  the  OS  magnum. 


The  Os  Magnum. 

The  OS  magnum  is  the  largest  bone  of  the  carpus,  its  distinctive 
characters  being  that  it  is  composed  of  a  head,  neck,  and  body.  The 
superior  and  external  aspects  of  the  head  are  convex,  and  merge 
gradually  into  each  other.  The  cartilage  of  the  superior  aspect  is 
prolonged  more  behind  than  in  front,  and  articulates  with  the  semi- 
lunar. The  external  aspect  of  the  head  articulates  with  the  scaphoid. 
The  internal  aspect  of  the  head  is  flat,  and  presents  the  commence- 
ment of  the  facet  for  the  unciform  bone.  The  neck  is  mainly  present 
in  front  and  behind. 

The  body  is  quadrilateral,  and  narrower  in  front  than  behind. 
The  'palmar  and  dorsal  surfaces  are  rough,  the  former  giving  origin 
to  fibres  of  the  adductor  obliquus  pollicis.  The  external  surface, 
which  is  continuous  with  the  outer  convex  aspect  of  the  head, 
presents  anteriorly  a  facet  for  the  trapezoid.  The  internal  surface 
presents  at  its  back  part  the  lower  portion  of  the  facet  for  the 
unciform,  which  is  here  narrow.  The  inferior  surface  is  narrow  in 
front,  but  broad  behind,  and  the  internal  of  the  two  posterior 
angles  is  elongated  downwards  and  inwards.    This  surface  presents 


THE  BONES  OF  THE   UPPER  LIMB  189 

three  facets.  The  middle  one  is  the  largest,  and  articulates  with 
the  third  metacarpal  bone.  The  external  one  is  a  narrow,  concave 
strip  for  the  second  metacarpal  bone.     The   internal   one,   small 

A  B 

For  Scaphoid 

Head  (for  Semilunar 

For  Tr.ipezoid  For  Unciform  _  . 


For  3rd  Metacarpal 


__  For  2nd  Metacarpal 

For  Unciform , 

For  4th  Metacarpal 

Fig.     115.  —  The     Right     Os     Magnum. 
A,  External  View  ;  B,  Internal  View. 

and  circular,  tips  inferiorly  the  projecting  postero-internal  angle, 
and  articulates  with  the  fourth  metacarpal  bone. 

Articulations. — Superiorly  with  the  semilunar,  superiorly  and 
externally  with  the  scaphoid,  inferiorly  with  the  second,  third,  and 
fourth  metacarpal  bones,  externally  with  the  trapezoid,  and  internally 
with  the  unciform. 

The  Unciform  Bone. 

The  unciform  bone  is  characterized  by  a  hook-like  process  on  its 
palmar  surface.  It  is  triangular,  or  wedge-shaped,  and  lies  with  its 
base  downwards.  The  superior  extremity  presents  a  narrow  facet 
for  the  semilunar.  The  inferior  surface  is  divided  by  an  antero- 
posterior ridge  into  two  quadrilateral  facets,  the  outer  of  which 
articulates  with  the  fourth,  and  the  inner  with  the  fifth,  meta- 
carpal bone.  The  palmar  surface,  which  is  rough,  presents  at  its 
lower  and  inner  part  a  prominent  curved  projection,  called  the  unci- 
.form  process.  This  process  is  laterally  compressed,  the  external 
surface  being  concave  and  the  internal  convex,  so  that  the  direction 
of  the  curve  is  outwards.  Its  borders  are  superior,  inferior,  and 
anterior.  The  internal  surface  gives  origin  to  the  flexor  brevis,  and 
opponens,  minimi  digiti,  and  close  to  the  root  it  presents  the  ulnar 
groove  for  the  deep  branches  of  the  ulnar  artery  and  nerve.  The 
anterior  border  gives  attachment  to  the  anterior  annular  and  pisi- 
uncinate  ligaments.  The  dorsal  surface  is  extensive  and  rough. 
The  external  surface  presents  an  elongated  facet,  broad  above  and 
narrow  below,  where  it  is  confined  to  the  back  part,  for  articula- 
tion with  the  OS  magnum.  The  sup ero -internal  surface  is  con- 
cavo-convex from  below  upwards,  and  articulates  with  the  cuneiform. 
The  internal  border,  situated  at  the  meeting  of  the  supcro-internal 
and  inferior  surfaces,  is  narrow  and  rough,  its  direction  being  from 
before  backwards. 


1 90 


A   MANUAL  OF  ANATOMY 


Articulations. — Superiorly  with  the  semilunar,  sup ero -internally 
with  the  cuneiform,  inferiorly  with  the  fourth  and  fifth  metacarpal 
bones,  and  externally  with  the  os  magnum. 


Unciform  Process 


B 

For  Semilunar 


For  5  th 
Metacarpal. 


Inferior  Aspect 


Unciform  Process,.__ 


For  4th  Metacarpal  For  sth  Metacarpal 

Fig.   1 1 6. — The  Right  Unciform  Bone. 
A,  External  View ;  B,  Supero-internal  View  ;    C,  Inferior  View. 


The  carpus  as  a  whole  is  narrower  above  than  below.  The  dorsal 
aspect  is  irregularly  convex,  and  the  dorsal  surfaces  of  the  bones'  of 
the  first  row  (exclusive  of  the  pisiform)  are  narrow,  but  in  the  second 
row  they  are  broad,  this  being  reversed  on  the  palmar  aspect.  It 
is  to  be  noted  that  the  postero-internal  angles  of  the  trapezium, 
trapezoid,  and  os  magnum  are  distinctly  elongated.  The  palmar 
aspect  is  rendered  concave  by  the  tuberosities  of  the  scaphoid  and 
trapezium  externally,  and  the  pisiform  bone  and  unciform  process 
internally.  These  projections  give  attachment  to  the  anterior 
annular  ligament,  which  with  the  palmar  concavity  forms  a  fibro- 
osseous  canal  for  the  passage  of  the  flexor  tendons  and  median 
nerve.  The  superior  aspect,  which  is  directed  backwards  as  well  as 
upwards,  is  convex,  and  articulates  with  the  radius  and  triangular 
interarticular  fibro-cartilage.  The  inferior  or  metacarpal  aspect  is 
somewhat  undulating.  The  inferior  surface  of  the  first  row  is  for 
the  most  part  deeply  concave,  but  externally  it  is  convex.  The 
superior  surface  of  the  second  row  is  concavo-convex  from  without 
inwards,  the  concavity  being  formed  by  the  trapezium  and  trapezoid, 
into  which  the  scaphoid  convexity  above  is  received,  whilst  the  con- 


THE  BONES  OF  THE  UPPER  LIMB  191 

vexity  is  formed  by  the  os  magnum  and  unciform,  and  is  received 
into  the  concavity  above. 

Structure. — ^The  carpal  bones  are  each  composed  of  cancellated 
tissue,  covered  by  a  thin  shell  of  compact  bone. 

Varieties. — The  number  of  carpal  bones  is  sometimes  increased  to  nine, 
wliich  is  brought  about  in  one  or  other  of  the  following  ways  :  (a)  the  scaphoid, 
semilunar,  trapezium,  or  os  magnum  may  be  divided  into  two  parts  ;  (b)  the 
styloid  process  at  the  base  of  the  third  metacarpal,  or  the  hook-like  process  of 
the  unciform,  may  remain  an  independent  ossicle  ;  or  (c)  there  may  be  a 
persistent  05  centrale,  situated  on  the  dorsal  aspect  between  the  scaphoid, 
trapezoid,  and  os  magnum. 

Ossification. — The  carpal  bones  are  all  cartilaginous  at  birth.  Each 
ossifies  from  one  centre,  in  the  following  order,-  and  at  the  following  periods 
approximately  : 

Os  magnum,  ist  year.  Trapezium,  5  th  year. 

Unciform,  2nd  year.  Scaphoid,  6th  year. 

Cuneiform,  3rd  year.  Trapezoid,  7th  year. 

Semilunar,  sth  year.  Pisiform,  12th  year. 

The  Os  Centrale. — This  appears  as  an  independent  cartilage  in  the  second 
month  of  intra-uterine  life  on  the  dorsal  aspect  of  the  carpus  between  the 
cartilaginous  scaphoid,  trapezoid,  and  os  magnum.  As  a  general  rule  it 
joins  the  cartilage  of  the  scaphoid  in  the  third  month,  but  it  may  ossify 
independently,  and  remain  persistent,  as  in  the  water  tortoises  and  many 
apes.  It  is  the  representative  of  the  navicular  or  scaphoid  bone  of  the 
tarsus. 

The  Metacarpus. 

The  metacarpus  forms  the  palm  of  the  hand,  and  is  composed  of 
five  long  bones,  which  are  named  numerically  from  without  inwards, 
that  of  the  thumb  being  the  first.  Each  bone  is  divisible  into  a 
shaft  and  two  extremities,  proximal  and  distal.  The  shaft  is  tri- 
angular, except  in  the  first,  in  which  it  is  compressed  from  before 
backwards.  It  is  longitudinally  concave  on  the  palmar  aspect, 
and  presents  three  surfaces,  two  lateral  and  a  dorsal.  The 
lateral  surfaces  give  attachment  to  interosseous  muscles,  and  are 
separated  from  each  other  by  an  anterior  border.  The  dorsal 
surface  over  its  proximal  third  presents  a  median  ridge,  which 
in  the  case  of  the  fifth  metacarpal  is  placed  towards  the  inner 
side.  Over  the  distal  two-thirds  the  ridge  bifurcates,  its  divisions 
passing  each  to  the  dorsal  tubercle  on  the  side  of  the  head,  and 
enclosing  between  them  a  flat  triangular  surface. 

The  head  or  distal  extremity,  which  articulates  with  a  first 
phalanx,  is  convex,  and  covered  by  cartilage,  except  laterally. 
The  cartilage  is  prolonged  farther  on  the  palmar  than  on  the 
dorsal  surface,  and  terminates  anteriorly  in  a  concave  border,  the 
extremities  of  which  form  small  cornua.  Laterally  the  head  is 
compressed,  and  presents  at  either  side  a  dorsal  tubercle  and  palmar 
depression  for  the  lateral  metacarpo-phalangeal  ligament. 

The  base  or  proximal  extremity  is  irregularly  quadrilateral, 
being  broader  on  its  dorsal  than  palmar  surface,  and  it  articulates 


192 


A   MANUAL  OF  ANATOMY 


superiorly  with  the   carpus,  and  at  either  side  with   its  fellows, 
except  in  the  case  of  the  first. 

The  First  Metacarpal  Bone. — ^This  is  shorter  than  any  of  the  others, 
and  its  shaft  is  compressed  from  before  backwards.  The  palmar 
aspect,  which  has  an  inclination  inwards,  has  the  anterior  border 
placed  nearer  the  inner  than  the  outer  side.  The  outer  margin 
and  adjacent  part  of  the  palmar  aspect  give  insertion  to 
the  opponens  pollicis,  and  the  inner  margin  over  its  proximal 
half  gives  origin  to  the  outer  head  of  the  first  dorsal  inter- 
osseous. The  dorsal  surface  is  slightly  convex,  and  is  destitute  of 
the  ridge  which  characterizes  the  others.  The  head  is  elongated 
transversely,  and  presents  on  its  palmar  surface  two  shallow  de- 
pressions for  the  sesamoid  bones.     The  base  is  transversely  oval. 

Head 


--^-Grooves  for  Sesamoid  Bones 


Medullary  Foramen 

—  External  Border  for  Opponens  Pollicis 


._  Internal  Border  for  ist  Dorsal  Interosseous 
(over  proximal  half) 


■  For  Extensor  Ossis  Metacarpi  Pollicis 


-^  —  tSase 


Fig.   117. — The  First  Right  Metacarpal  Bone 
(Palmar  View). 


and  has  a  saddle-shaped  articular  surface  for  the  trapezium,  which 
is  concave  from  before  backwards,  and  convex  from  side  to  side. 
Externally  it  presents  a  tubercle  for  the  insertion  of  the  extensor 
ossis  metacarpi  pollicis,  and  internally  it  gives  origin  to  the  deep 
head  of  the  flexor  brevis  pollicis.    . 

Articulations. — Superiorly  with  the  trapezium,  and  inferiorly  with 
the  first  phalanx  of  the  thumb,  and  the  two  sesamoid  bones. 

The  Second  Metacarpal  Bone. — ^This  is  the  longest.  Its  base, 
which  is  the  largest,  is  deeply  excavated  superiorly  for  the  trapezoid, 
being  concave  from  side  to  side.  Internal  to  this,  it  rises  into  a  promi- 
nent border,  which  presents  a  faceted  strip  for  the  os  magnum,  and 
externally  at  the  back  part  there  is  a  small  facet  for  the  trapezium. 
The  inner  side  presents  an  antero-posterior  facet,  notched  at  the 
centre  of  its  lower  border,  for  the  third  metacarpal.  The  palmar 
aspect  gives  insertion  to  the  principal  part  of  the  tendon  of  the  flexor 
carpi  radialis,  and  origin  to  a  portion  of  the  adductor  obliquus 


THE  BONES  OF  THE   UPPER  LIMB 


193 


poUicis.  The  dorsal  aspect  at  its  outer  part  gives  insertion  to  the 
extensor  carpi  radialis  longior,  and  at  its  inner  part  to  a  small  slip 
of  the  extensor  carpi  radialis  brevior,  there  being  a  notch  between 
the  two  impressions.  The  shaft  gives  origin  to  the  first  and  second 
dorsal,  and  first  palmar,  interossei. 

Articulations. — Superiorly  with  the  trapezium,  trapezoid,  and  os 
magnum,  inlernidly  with  the  third  metacarpal,  and  inferiorly  with 
the  first  phalanx  of  the  index  finger. 


Head 
Palmar  Depression- __ 
Dorsal  Tubercle^  ' 

MeduUarj'  Foramen 1. 

Internal  Surface.-. 


_ .   External  Surface 


-  For  Trapezium 


For  3rd  Metacarpal  For  Os  Magnum  \' 

For  Trapezoid 

Fig.   118. — The  Second  Right  Metacarpal  Bone. 
A,  Internal  View;   B,  External  View. 

The  Third  Metacarpal  Bone.— This  is  next  in  length  to  the  second. 
Its  distinctive  character  is  the  styloid  process  at  the  base.  The 
superior  surface  of  the  base  articulates  with  the  os  magnum.  The 
outer  side  presents  an  antero-posterior  facet,  notched  at  its  lower 
border,  for  the  second  metacarpal.  The  inner  side  presents  two 
circular  facets,  separated  by  a  rough  vertical  groove,  for  the  fourth 
metacarpal.  The  palmar  aspect  gives  insertion  to  a  sli|)  of  the  flexor 
carpi  radialis,  and  f)rigin  to  a  portion  of  the  adductor  obliquus 
pollicis.  The  dorsal  aspect  externally  gives  insertion  to  the  i)rin- 
cipal  part  of  the  extensor  carpi  radiaUs  brevior,  and  it  is  projected 
upwards  at  its  outer  angle  into  the  styloid  process.  The  anterior 
border  of  the  shaft,  over  its  distal  two-thirds,  gives  origin  to  the 

13 


194 


A   MANUAL  OF  ANATOMY 


adductor  transversus  pollicis,  and  the  shaft  also  affords  origin  to 
the  second  and  third  dorsal  interossei. 

Articulations. — Superiorly  with  the  os  magnum,  and  the  second 
and  fourth  metacarpal  bones,  and  inferiorly  with  the  first  phalanx 
of  the  middle  finger. 

The  Fourth  Metacarpal  Bone. — This  is  shorter  than  the  third,  and. 
its  base  is  small.  The  outer  side  of  the  base  presents  two  circular 
facets,  separated  by  a  rough  vertical  groove,  for  the  third  metacarpal. 
The  inner  side  has  a  semi-oval  facet  for  the  fifth  metacarpal.  The 
superior  surface  presents  two  facets.     One  is  large  for  the  unci- 


Internal  Surface-- 


For  4th  Metacarpal.-..^;; 


For  Os  Magnum 


External  Surface 
,_.  Medullaiy  Foramen 


_  _  For  ?nd  Metacarpa 


Styloid  Process 

Fig.  119. — The  Third  Right  Metacarpal  Bone. 
A,  Internal  View;  B,  External  View. 


form,  whilst  the  other,  situated  at  the  outer  and  posterior  part, 
is  small  for  the  os  magnum.  The  shaft  gives  origin  to  the  third 
and  fourth  dorsal,  and  second  palmar,  interossei. 

Articulations. — Superiorly  with  the  os  magnum,  unciform,  and 
third  and  fifth  metacarpals,  and  inferiorly  with  the  first  phalanx 
of  the  ring  finger. 

The  Fifth  Metacarpal  Bone. — ^This  is  shorter  than  the  fourth,  but 
longer  than  the  first.  The  superior  surface  of  the  base  presents  a 
quadrilateral  facet  for  the  unciform.  The  outer  side  has  a  semi-oval 
facet  for  the  fourth  metacarpal,  and  the  inner  side  presents  a  rounded 
tubercle  for  the  insertion  of  the  extensor  carpi  ulnaris.     The  inner 


THE  BONES  OF  THE  UPPER  LIMB 
A  B 


195 


.  External  Surface  and 
Medullary  Foramen 


r--^For  3id  Metacarpal 


For  5th  Metacarpal  For  Os  MaL;num 

Fig.  I  jo. — The  Fourth  Right  Metacarpal  Bone. 
A,  Internal  View;   B,   External  View. 


Kxternal  Surface  and 

.Medullary  Foramen 


For  Unciforiri  For  .,th  Metacarpal  ; 

For  4th  Metacarpal 


Tubercle  for  Extensor 
For  Unc'if,,,  n.  ^"="■1"  Ul"aris 


Fig.   121.— The  Fifth  Right  Metacarpal  Bonk. 
A,  External  View  ;  B,  Dorsal  View. 


13—2 


196  A   MANUAL  OF  ANATOMY 

margin  of  the  shaft  gives  insertion  to  the  opponens  minimi  digiti, 
and  the  shaft  also  affords  origin  to  the  fourth  dorsal,  and  third 
palmar,  interossei. 

Articulations. — Superiorly  with  the  unciform,  externally  with  the 
fourth  metacarpal,  and  inferiorly  with  the  first  phalanx  of  the 
little  finger. 

Each  metacarpal  bone  presents  a  medullary  foramen,  that  of 
the  first,  and  usually  that  of  the  second,  being  situated  on  the 
inner  or  ulnar  side  of  each  shaft,  whilst  those  of  the  third,  fourth, 
and  fifth  are  situated  on  the  outer  or  radial  side*  The  foramen  of 
the  first  and  the  canal  to  which  it  leads  are  directed  downwards 
towards  the  head,  but  those  of  the  other  four  are  directed  upwards 
towards  the  base.  The  mediillary  artery  of  the  first  metacarpal  is 
furnished  by  the  arteria  princeps  poUicis,  those  of  the  second  and 
third  are  branches  of  the  first  palmar  interosseous,  that  of  the 
fourth  is  furnished  by  the  second  palmar  interosseous,  and  that  of 
the  fifth  by  the  third  palmar  interosseous,  arteries. 

Structure. — The  structure  is  that  of  a  long  bone. 


Tuberosity 


Fig.  122. — The  Bases  of  the  Right  Metacarpal  Bones  (Superior  View). 

The  metacarpus  as  a  whole  is  concave  from  side  to  side,  and  also 
longitudinally,  on  its  palmar  aspect,  whilst  the  dorsal  aspect  is  con- 
vex. The  first  metacarpal  stands  off  at  an  angle  from  its  fellows, 
and  occupies  a  more  anterior  plane,  thus  fitting  it  for  the  important 
movement  of  opposition  on  the  part  of  the  thumb.  The  other  four 
metacarpals  lie  very  nearly  parallel  with  each  other.  They  articu- 
late with  one  another  by  their  bases,  but  diverge  slightly  towards 
their  heads,  where  they  are  connected  on  their  palmar  aspects  by 
the  transverse  metacarpal  ligament.  Between  the  five  bones  there 
are  four  intervals,  called  interosseoiis  spaces,  the  first  being  that 
between  the  first  and  second  bones. 


The  Phalanges. 

The  phalanges  are  also  known  as  ossa  internodia,  from  their 
position  between  the  joints  of  the  fingers.  The  fingers,  of  which 
they  form  the  framework,  are  called  pollex  or  thumb,  index,  middle, 

*  Of  lOO  second  metacarpal  bones  examined,  59  had  the  medullary  foramen 
on  the  inner  side,  and  41  on  the  outer. 


THE  BONES  OF  THE   UPPER  LIMB 


197 


Ungual  Process 


"  Proximal  Extremity 


Proximal  Extremity 


ring,  and  little,  respectively.  The  number  of  phalanges  is  fourteen, 
three  for  each  of  the  four  inner  fingers,  and  two  for  the  thumb. 
They  are  arranged  in  rows,  both  longitudinally  and  transversely, 
and  they  diminish  in  length  from  above  downwards.  They  are 
distinguished  as  first  or  proximal,  second  or  intermediate,  and 
third,  distal,  or  ungual,  except  in  the  case  of  the  thumb,  where  the 
second  is  wanting. 

The  First  Phalanx. — The  shaft  is  compressed  from  before  back- 
wards, flat  and  concave  longitudinally  on  the  palmar  aspect,  and 
convex  on  the  dorsal.  The  palmar  surface  presents  at  either  side  a 
rough  border  for  the  sheath  of  the  flexor  tendons.  The  proximal  end 
or  base  is  enlarged,  and  presents 
superiorly  a  concave  articular  sur- 
face, transversely  oval,  for  the 
head  of  a  metacarpal  bone,  and 
at  either  side  a  slight  tubercular 
enlargement.  The  distal  end  is 
small,  and  presents  a  trochlear 
surface,  grooved  at  the  centre  and 
elevated  at  either  side  of  this  into 
a  small  condyle,  for  articulation 
with  the  second  phalanx,  except 
in  the  case  of  the  thumb,  where 
it  articulates  with  the  ungual 
phalanx.  The  cartilage  of  the 
distal  end  is  prolonged  more  on 
the  palmar  aspect  than  on  the 
dorsal.  At  either  side  it  presents 
a  depression  for  the  lateral  inter- 
phalangeal  ligament. 

The  Second  Phalanx. — This  is 
shorter  and  smaller  than  the  first, 
from  which  it  is  distinguished  by 
having  on  its  proximal  end  or  base 
two  shallow  articular  depressions, 
separated  by  a  median  antero- 
posterior ridge,  for  the  distal  end 
of  the  first  phalanx.  The  distal  end  reseml^les  that  of  a  first 
phalanx,  except  that  it  is  smaller.  The  shaft  resembles  that  of  a 
first.  Its  palmar  surface  presents  at  the  centre  of  the  lateral  borders 
two  rough  impressions,  one  at  either  side,  which  give  insertion  to  the 
divisions  of  a  superficial  flexor  tendon.  The  dorsal  surface  of  the 
base  is  marked  by  a  rough  transverse  ridge  for  the  insertion  of 
the  midfUc  flivision  of  a  common  extensor  tendon. 

The  Third  Phalanx.— This  is  of  small  size.  The  proximal  end  or 
base  resembles  that  of  a  second  phalanx,  and  has  in  front  a  rough 
transverse  ridge  for  the  insertion  of  a  deep  flexor  tendon,  whilst  the 
dorsal  surface  gives  insertifjn  to  the  two  lateral  divisions  of  a  common 
extensor  tendon.    The  distal  end  j^resents  a  rough,  tapering,  convex 


Proximal  Extremity 


Fig.   123. — The  Phalanges  of  the 
Middle  Finger  (Dorsal  View). 


198  A  MANUAL  OF  ANATOMY 

border,  the  roughness  being  continued  for  a  little  on  the  palmar 
aspect.  This  roughness,  which  is  semilunar,  is  called  the  ungual 
process,  and  it  supports  the  nail  and  the  tissues  forming  the  pulp 
of  the  finger. 

The  two  phalanges  of  the  thumb  are  of  large  size. 

Special  Muscular  Attachments. — The  base  of  the  proximal  phalanx  of  the 
thumb  gives  insertion  externally  to  the  abductor  pollicis  and  superficial  head  of 
the  flexor  brevis  pollicis,  internally  to  the  deep  head  of  the  flexor  brevis  pol- 
licis, adductor  obliquus  pollicis,  and  adductor  transversus  pollicis,  and 
posteriorly  to  the  extensor  brevis  pollicis.  The  base  of  the  distal  phalanx 
gives  insertion  anteriorly  to  the  flexor  longus  pollicis,  and  posteriorly  to 
the  extensor  longus  pollicis.  The  base  of  the  proximal  phalanx  of  the  index 
finger  gives  partial  insertion  to  the  first  dorsal  interosseous  externally,  and  the 
first  palmar  interosseous  internally.  The  base  of  the  proximal  phalanx  of  the 
middle  finger  gives  partial  insertion  to  the  second  dorsal  interosseous  ex- 
ternally, and  the  third  dorsal  interosseous  internally.   The  base  of  the  proximal 


5th  Year  Year  6th  Year 

\     \     i        7th  Year 
3rd  Year      XT-Tx/   5  th  Year 
I2th  \  ear  -v    «   w 

2nd  Year  ._ 


~v  Appear  from  the  3rd 
]-      to  the  5th  Year, 
-*     and  join  about  20 


Appears  from  the  3rd  to  the  5th  Year, 
and  joins  about  20 


Appear  about  the  oth  Week 
(intra-uterine) 


Fig.    124. — Ossification    of    the    Bones    of    the    Hand. 
A,  2nd  Metacarpal  ;  B,  ist  Metacarpal  ;  C,  ist  Phalanx. 

phalanx  of  the  ring  finger  gives  partial  insertion  to  the  second  palmar  inter- 
osseous externally,  and  the  fourth  dorsal  interosseous  internally.  The  base  of 
the  proximal  phalanx  of  the  little  finger  gives  partial  insertion  to  the  third 
palmar  interosseous  externally,  and  insertion  to  the  abductor  minimi  digiti 
(partially)  and  flexor  brevis  minimi  digiti  internally. 

The  medullary  foramen  of  each  phalanx  is  situated  on  the  palmar 
aspect  of  the  shaft,  not  far  from  the  distal  end.  It  may  be  single, 
in  which  case  it  is  mesially  placed,  or  there  may  be  two,  one  close 
to  each  lateral  border.  In  all  cases  the  direction  of  the  foramen 
and  the  canal  to  which  it  leads  is  downwards  towards  the  distal  end. 
The  medullary  arteries  are  furnished  by  the  corresponding  palmar 
digital  arteries. 

Structure. — The  structure  is  that  of  a  long  bone.  In  the  terminal 
phalanges  the  medullary  canal  is  replaced  by  cancellated  tissue  with 
wide  meshes. 


THE  BONES  OE  THE  UPPER  LIMB  199 

The  Sesamoid  Bones.  —  These  are  usually  two  in  number, 
and  are  placed  on  the  palmar  aspect  of  the  head  of  the  first 
metacarpal  bone.  They  are  originally  nodules  of  cartilage,  one  of 
which  is  developed  in  the  tendon  of  insertion  of  the  superficial  head 
of  the  flexor  brevis  pollicis,  and  the  other  in  that  of  the  adductor 
obliquus  pollicis.  Similar  ossicles  are  sometimes  met  with  on  the 
palmar  aspects  of  the  heads  of  the  second  and  fifth  metacarpal 
bones. 

Ossification  of  tlie  Metacarpal  Bones  and  Phalanges. — Each  of  these  bones 
ossifies  in  cartilage  from  one  primary,  and  one  secondary,  centre.  The  primary 
centre  appears  about  tlie  ninth  week  of  intra-uterine  life  at  the  middle  of  the 
shaft,  except  in  the  case  of  the  ungual  phalanges,  in  which  it  appears  at  the 
distal  end.  In  the  inner  four  metacarpal  bones  the  epiphysis  is  placed  at  the 
distal  end  or  head,  but  in  the  first  metacarpal  bone  (that  of  the  thumb),  and 
in  all  the  phalanges,  it  is  placed  at  the  proximal  end  or  base.  The  secondary 
centre  in  each  case  appears  from  the  thiyd  to  the  fifth  year,  and  the  epiphyses 
are  united  to  their  respective  shafts  about  the  twentieth  year.  The  first 
metacarpal  bone  has  sometimes  a  thin  distal  epiphysis,  as  well  as  a  proximal, 
which  begins  to  ossify  about  the  eighth  year,  and  joins  soon  thereafter  ;  and 
the  second  metacarpal  bone  has  sometimes  a  proximal  epiphysis,  as  well  as  a 
distal.  The  first  metacarpal  bone,  being  a  phalanx  as  regards  its  epiphysial 
ossification,  is  regarded  by  some  as  the  proximal  phalanx  of  the  thumb, 
according  to  which  view  the  bone  wanting  in  the  thumb  is  the  metacarpal 
bone.  The  styloid  process  of  the  third  metacarpal  bone  has  sometimes  a 
special  centre,  and,  instead  of  joining  the  rest  of  the  bone,  it  may  remain 
persistent  as  a  supernumerary  bone  of  the  carpus,  or  it  may  unite  with  the 
postero-internal  angle  of  the  trapezoid. 


2Sd 


A  MANUAL  OF  ANATOMY 


Pisi-uncinate  Lisament 


Abductoi  PoUicis 
Opponens  Pollicis^ 

Superficial  Head  of  Flexor.,^^   / 
Brevis  PoUicis  ^■ 

Ext.  Ossis  Metacarpi  Poll.---__ 

Deep  Head  of  Flex.  Brevis  Pollicis- 

Flexor  Carpi  Radialis 

Opponens  Pollicis~~ 


Abd.  PoUicis  and  Superf. 

Head  of  Flex.  Brev.  Poll. 

Extensor  Brevis  PoUicis 


Deep  Head  of  Flex.  Brev, 

Poll.,  Add.  Obliq.  Poll. 

and  Add.  Trans.  Poll. 


Extensor  Longus- 
Poll. 
Flexor  Longus  Poll  - 


,  Flexor  Carpi  Ulnaris 

--Abductor  Minimi  Digiti 

__  Adductor  Obliquus  PoUicis 

Flex.  Brev.  and  Oppon.  Min.  Dig. 
Pisi-metacarpal  Ligament 


—  Adduct.  Transvers.  Poll. 
Opponens  Minimi  Digiti 


Flexor  Sublimis  Digitorum.^_. 


Flexor  Profundus  Digitorum 


Abductor  Minimi  Digiti 

and  Flexor  Brevis 

Minimi  Digiti 


Fig.    125. — The  Right  Hand  (Palmar  Surface). 


THE  BONES  OF  THE  UPPER  LIMB 


Scaphoid 

Os  Magnum 


Cuneiform 
Pisiform 

Unciform  _  ^^^(- '•■. 

Extensor  Carpi  _ 
Ulnaris 


Trapezoid 

Tiapezium 

Extensor  Carpi  Radialis  Longior 

-  Extensor  Ossis  Metacarpi  Pollicis 
Extensor  Carpi  Radialis  Brevior 


Extensor 
Brevis  Pollicis 

Deep  Head  of  Flexor 

Brev.  Poll.,  Adductor 

Obliquus  Poll.,  and 

Add.Transversus  Poll. 


Extensor  Longus 
Pollicis 


^>  Extensor  Communis  Digitorum 


Fig.   126. — The  Right  PIand  (Dorsal  Surface). 


A  MANUAL  OF  ANATOMY 


IV.  THE  BONES  OF  THE  LOWER  LIMB. 

The  lower  limb  is  arranged  in  four  divisions,  namely,  hip,  or 
pelvic  girdle,  thigh,  leg,  and  foot.  The  pelvic  girdle  consists  of 
the  OS  innominatum  ;  the  thigh  comprises  the  femur,  with  which 
is  associated  the  patella  ;  the  leg  is  composed  of  the  tibia  and 
fibula  ;  and  the  foot  is  subdivided  into  a  tarsus,  consisting  of  seven 
bones,  a  metatarsus,  comprising  five  bones,  and  phalanges,  which 
are  fourteen  in  number. 


The  Os  Innominatum. 

The  OS  innominatum  (os  coxae)  forms  the  lateral,  and  one  half  of 
the  anterior,  wall  of  the  pelvis.  It  is  much  twisted,  quadrilateral, 
and  constricted  about  the  centre.  The  external  surface  is  charac- 
terized by  the  acetabulum,,  and  below  and  internal  to  this  is  the 
obturator  foramen.  In  early  life  the  bone  is  composed  of  three 
parts — ilium,  ischium,  and  os  pubis — which  unite  in  the  acetabulum, 
and  in  the  adult  it  is  described  under  these  three  divisions. 

The  ilium  is  the  expanded  portion  above  the  acetabulum,  of 
which  it  forms  rather  less  than  the  upper  two-fifths.  It  presents 
three  borders  and  two  surfaces. 

The  superior  border  or  crest  is  thick  over  its  anterior  and 
posterior  thirds,  but  thin  over  the  middle  third.  It  presents 
two  curves — anterior  with  the  concavity  directed  inwards,  and 
posterior  with  the  concavity  outwards.  Anteriorly  it  terminates 
in  the  anterior  stiperior  spine,  which  gives  attachment  to  Poupart's 
ligament  and  a  portion  of  the  sartorius.  Posteriorly  it  ends 
in  the  posterior  superior  spine,  which  gives  attachment  to  the 
oblique  sacro-iliac  ligament.  The  crest  has  two  lips  and  an  inter- 
vening space.  The  outer  lip  presents  a  tubercular  prominence 
about  3  inches  from  the  anterior  superior  spine.  Over  its  whole 
extent  this  lip  gives  attachment  to  the  iliac  fascia  lata  ;  for  i^  inches 
in  front,  to  the  tensor  fasciae  femoris  ;  over  its  anterior  half,  to  the 
obliquus  externus  abdominis ;  and  a  little  behind  this,  to  the  latis- 
simus  dorsi.  The  intervening  space  over  its  anterior  two-thirds 
gives  origin  to  the  obliquus  internus  abdominis,  and  over  its  pos- 
terior fifth,  to  the  erector  spinae.  The  inner  lip  over  its  anterior  two- 
thirds  gives  origin  to  the  transversalis  abdominis,  and  for  about 
2  inches  posteriorly,  to  the  ilio-lumbar  ligament  and  quadratus 
lumborum.  Immediately  within  the  inner  lip,  over  its  anterior  two- 
thirds,  the  fascia  transversalis  and  fascia  iliaca  take  attachment. 

The  anterior  border  extends  from  the  anterior  superior  spine  to 
the  ilio-pectineal  eminence.  Superiorly  it  presents  the  anterior  inter- 
spinous  notch,  the  upper  part  of  which  gives  partial  origin  to  the 
sartorius.  Below  this  notch  is  the  anterior  inferior  spine,  which 
gives  origin  anteriorly  to  the  straight  head  of  the  rectus  femoris, 
and  inferiorl   ,  to  the  ilio-femoral  ligament.     Internal  to  this  spine 


THE  BONES  OF  THE  LOWER  LIMB 


Transversalis  Abdominis         Crest 
Obliquus  Internus  Abdominis 
Middle  Gluteal  Line 

Gluteus  Medius 
Latissimus  Dorsi 


Obliquus  Externus  Abdominis 


Superior  Gluteal  Line 
Gluteus  Maximus ,     ff 


Posterior  Superior  . 
Iliac  Spine 

Posterior  Inferior 
Iliac  Spine 


Pyriformis  ' 
Great  Sciatic  Notch-' 


Ischial  Spine  — - 
Gemellus  Superiot 


Gemellus  Inferior^ 
Obturator  Groove.- -"J 
Quadratus  Femoris_- 
Semimembranosus 
Semicendinosus  and  Long  Head  of 
Biceps 

Tuber  Ischii  ' 


Adductor  Magnus' 


Gluteus  Minimus 


Xensor  Fasciae 
Femoris 


'  Anterior  Superior 
Iliac  Spine 

Inferior  Gluteal  Line 

Anterior  Inferior  Spine 
__  and  Straight  Head  of 
Rectus  Femoris 
Reflected  Head  of  Rectus 

,  Acetaljulum 


Cotyloid  Notch 
,Pectineus 
^  ^y  Pubic  Spire 

Pubic  Crest  and 

Rectus  Abdominis 
Pubic  Angle 
"■-Adductor  Longus 
Symphysis  Pubis 

Gracilis 
^\dductor  Brevis 

Descending  Pubic  Ramus 
Adductor  Magtms 


Ischial  Ramus 


Obturator  Externus 


Fig.  127. — The  Right  Os  Innominatum  (External  View). 


204  A  MANUAL  OF  ANATOMY 

there  is  a  groove  for  the  passage  of  the  ilio-psoas,  and  internal  to 
the  groove  is  the  ilio-pectineal  eminence,  which  marks  the  junction 
of  the  ihum  and  superior  pubic  ramus.  This  eminence  gives  attach- 
ment to  the  iho-pectineal  intermuscular  septum,  and,  it  may  be, 
partial  insertion  to  the  psoas  parvus. 

The  posterior  border  extends  from  the  posterior  superior  spine  to 
a  point  a  little  below  the  deepest  part  of  the  great  sciatic  notch, 
where  there  is  usually  a  faint  transverse  line  on  the  external 
surface,  indicating  the  place  of  junction  of  the  ilium  and  ischium. 
Superiorly  it  presents  the  posterior  interspinous  notch,  and  below 
this  the  posterior  inferior  spine,  which  gives  attachment  to  the  great 
sacro-sciatic  ligament,  whilst  immediately  below  this  it  gives 
origin  to  fibres  of  the  pyriformis.  Inferiorly  the  posterior  border 
forms  the  upper  part  of  the  great  sciatic  notch,  over  which  the 
pyriformis  passes  as  it  leaves  the  pelvis. 

The  external  surface  or  dorsum  ilii,  concavo-convex  from  behind 
forwards,  is  traversed  by  three  ridges,  called  the  superior,  middle, 
and  inferior  gluteal,  or  curved,  lines.  The  superior  ghiteal  line 
commences  at  the  outer  lip  of  the  crest  about  2  inches  in 
front  of  the  posterior  superior  spine,  and  passes  downwards  and 
forwards  to  the  upper  part  of  the  great  sciatic  notch.  The  surface 
which  it  cuts  off  is  semilunar,  and  its  upper  part  is  rough  for  the 
origin  of  fibres  of  the  gluteus  maximus.  The  middle  gluteal  line 
commences  at  the  outer  lip  of  the  crest  i^  inches  behind  the  anterior 
superior  spine,  and  passes  backwards  and  downwards  to  the  upper 
part  of  the  great  sciatic  notch,  where  it  terminates  close  to  the 
superior  line.  The  surface  included  between  the  middle  gluteal  line, 
crest,  and  superior  gluteal  line,  which  is  falciform,  gives  origin  to 
the  gluteus  medius.  The  inferior  ghdeal  line  commences  at  the 
lower  part  of  the  anterior  interspinous  notch,  whence  it  passes  back- 
wards to  the  deepest  part  of  the  great  sciatic  notch.  The  space 
between  the  inferior  and  middle  gluteal  lines  gives  origin  to  the 
gluteus  minimus.  Between  the  front  part  of  the  inferior  gluteal 
line  and  the  margin  of  the  acetabulum  there  is  a  short  transverse 
groove,  which  gives  origin  to  the  reflected  head  of  the  rectus  femoris. 
The  iliac  portion  of  the  bone  is  very  thin  and  translucent  toward 
the  upper  part  of  the  middle  third,  where  it  is  sometimes  perforated, 
and  it  presents  a  strong  rounded  ridge,  leading  upwards  from  the 
margin  of  the  acetabulum  to  the  tubercular  eminence  on  the  outer 
lip  of  the  crest.  There  is  also  a  strong  bar  of  bone  extending  from 
the  upper  margin  of  the  acetabulum  to  the  auricular  surface  on  the 
internal  aspect. 

The  internal  surface  is  divisible  into  an  anterior,  and  a  posterior, 
portion.  The  anterior  division,  which  represents  two-thirds,  is  sub- 
divided into  a  small  lower,  and  large  upper,  part  by  the  iliac  portion 
of  the  ilio-pectineal  line,  the  direction  of  which  is  forwards  and  down- 
wards. The  part  below  and  behind  the  line  enters  into  the  lateral 
wall  of  the  pelvis,  and  gives  origin  to  a  portion  of  the  obturator 
internus.     The  part  above  the  line  is  extensive  and  concave,  and 


THE  BONES  OF  THE  LOWER  LIMB  205 

forms  the  iliac  fossa,  which  lodges  the  ihacus  muscle.  The  iliac 
portion  of  the  ilio-pectineal  line  gives  attachment  to  the  fascia 
iliaca,  and  for  about  an  inch  posteriorly  to  the  parietal  pelvic  fascia. 
It  may  also  give  partial  insertion  to  the  psoas  parvus  near  the 
ilio-pectineal  eminence.  The  posterior  division  is  subdivided  into 
auricular,  ligamentous,  and  muscular  portions.  The  auricular 
division,  antero-inferior  in  position,  is  broad  in  front  and  narrow 
behind,  where  it  extends  over  the  inner  aspect  of  the  posterior 
inferior  spine.  It  is  covered  by  cartilage  in  the  recent  state,  and 
articulates  with  the  auricular  surface  of  the  sacrum.  The  liga- 
mentous division,  situated  above  and  behind  the  auricular,  presents 
an  elevation,  called  the  tuberosity,  for  the  posterior  sacro-iliac 
ligament,  its  surface  being  marked  by  several  pits.  The  muscular 
division,  placed  superiorly,  gives  origin  to  fibres  of  the  multifidus 
spinae. 

The  ischium  forms  the  lower  and  back  part  of  the  bone,  and 
is  divisible  into  a  body,  tuberosity,  and  ramus.  The  body  con- 
tributes rather  more  than  two-fifths  to  the  acetabulum,  and 
forms  the  greater  portion  of  its  non-articular  part.  It  is  some- 
what triangular,  the  truncated  apex  being  directed  downwards,  and 
its  surfaces  are  internal,  external,  and  posterior.  The  internal 
surface  extends  from  near  the  centre  of  the  ilio-pectineal  line 
to  the  ischial  spine,  and  is  narrow  above,  but  widens  inferiorly 
before  reaching  the  spine.  Its  place  of  junction  with  the  ilium  is 
indicated  by  a  line  passing  from  the  ilio-pectineal  eminence  back- 
wards and  downwards  to  a  point  a  little  below  the  deepest  part  of  the 
great  sciatic  notch.  Its  junction  with  the  superior  pubic  ramus 
is  marked  by  a  line  passing  from  the  ilio-pectineal  eminence  down- 
wards to  the  posterior  margin  of  the  obturator  foramen  about 
I  inch  below  its  upper  end.  This  surface  gives  origin  to  part 
of  the  obturator  internus.  The  external  stir/ace  enters  into  the 
acetabulum,  and  between  that  cavity  and  the  tuberosity  it  presents 
the  obturator  groove  for  the  tendon  of  the  obturator  externus.  The 
upper  part  of  this  groove  gives  attachment  to  the  ischio-capsular 
ligament.  The  posterior  surtace  is  limited  externally  by  the  brim  of 
the  acetabulum,  behind  by  the  posterior  border,  and  below  by  the 
upper  border,  of  the  tuberosity.  At  the  lower  part  it  presents  a 
portion  of  the  obturator  groove,  and  it  supports  the  pyriformis,  and 
the  sciatic  nerves  and  vessels. 

The  borders,  like  the  surfaces,  are  internal,  external,  and 
posterior.  The  internal  border  forms  a  portion  of  the  posterior 
margin  of  the  obturator  foramen,  and  is  sharp  for  the  obturator 
membrane.  It  sej)arates  the  internal  from  the  external  surface. 
The  external  border  forms  the  posterior  part  of  the  margin  of  the 
acetabulum,  and  gives  attachment  to  a  part  of  the  cotyloid 
ligament.  The  posterior  border  is  continuous  with  that  of  the 
ilium.  Superiorly  it  forms  the  lower  part  of  the  great  sciatic 
notch,  below  which  it  presents  a  j)rojection,  called  the  spine,  which 
has  an  inward  curve  towards  the  pelvis,  and  gives  attachment  to  the 


2o6  A   MANUAL  OF  ANATOMY 

following  structures  :  the  small  sacro-sciatic  ligament  at  the  tip, 
the  levator  ani,  coccygeus,  and  white  line  of  the  pelvic  fascia  on  the 
inner  surface,  and  the  gemellus  superior  along  the  lower  border.  The 
external  surface  (back)  supports,  from  within  outwards,  the  pudic 
nerve,  internal  pudic  vessels,  and  nerve  to  the  obturator  internus. 

r>w  ?'^^^'^"'^Ai,j       ■■  Transversalis  Abdominis 

Obliquus  Interims  Abdominis  i 

Quadratus  Lumborum 
/ 

'  Tuberosity 

Ligamentous  Surface 
Erector  Spinas 

,Multifidus 
Spinae 

Anterior  Superior-' 
Iliac  Spine 

Iliacus  ^^ 

Anterior  Inferior  __  _     _\                                  ^ji$^^S^^^^^iK  '  li  I  §  ^vf^\  Posterior  Superior 

Iliac  Spine            '   """     V       )'■                  <e^^^^^^fc»Z^:^'^^^^MfcWlfci»H  lluiw)  Iliac  Spine 

,,.            .       ,  -  .                      \i|J'           j^i^  ~^//^mil                      "^Jz.^-^  "Posterior  Inferior 

Ilio-pectineal  Line J(?.__^^^      /^^'\Ii     X                 ''\  Iliac  Spine 

Psoas  Parvus— •--- 7^  -T^^^lC^ -"""V.  '"    '■  Vn         "^^  \ 

Ilio-pectineal /   ,- J^^%M  V»  ^^  ^^v 

Eminence    "      '       I      fa3m,\t  \%  ^^,  'Auricular  Surface 

Obturator  Groove  V  jF.    'M^i%  \\\  ^  Great  Sciatic  Notch 

. »  —  —Coccygeus 

■  msa^-  1        r~ti    Ischial  Spine 

Superior /_  //'P^^^^-O?  \j^^ Levator  Ani 

Pubic  Ramus  /       //,/  ^*=-^  -  ^         PP^ Small  Sciatic  Notch 

Pubic  Spine  . 

I,  II       OBTURATOF 

Pubic  Crest  _  J/  ,,i,              V                                       .             .         - .-      ~ 

\  sMi.i/          V       FORAMEN              H            /       /^         ^Obturator  Internus 
Pubic  Angle  \  - 

Pubic  Body'  /v^         ,  •  xw  i  jmm^       -     t-  u      t    i,-- 

,' ^^-.>,/       tUV  y'  ^      \^M?W~  •  Tuber  Ischu 

Symphysis  Pubis  /  "^     -dmiJi^       »^         'j^^S^   ^. 

.'  /*-^      '***^^^-cT)^j''%  Transversus  Pennsei 

Levator  Ani  ,'        ^  \^  Ischio-cavernosus 

Descending  Pubic  Ramus 

I  Ischial  Ramus 

Compressor 
Urethrse 

Fig.   128. — The  Right  Os  Innominatum  (Internal  View). 

Below  the  spine  is  the  small  sciatic  notch,  which  is  covered  by  car- 
tilage in  the  recent  state  for  the  play  of  the  tendon  of  the  obturator 
internus. 

The  tuberosity  (tuber  ischii)  forms  the  thick  dependent  part, 
and  supports  the  body  in  the  sitting  posture.  The  wpfer  harder 
limits  inferiorly  the  obturator  groove  and  small  sciatic  notch,  and 


THE  BONES  OF  THE  LOWER  LIMB  207 

in  the  latter  situation  it  gives  origin  to  the  gemellus  inferior.  The 
inner  border  is  prominent  and  sharp,  and  gives  attachment  to  the 
great  sacro-sciatic  ligament.  The  outer  border  gives  origin  to  the 
quadratus  femoris.  The  anterior  border  is  sharp  and  prominent, 
and  forms  the  lower  part  of  the  posterior  margin  of  the  obturator 
foramen.  The  surfaces  are  postero-inferior,  external,  and  internal. 
The  postero-inferior  surface  lies  between  the  outer  and  inner  borders, 
and  is  divided  into  two  parts.  The  posterior  portion  is  somewhat 
quadrilateral,  and  is  subdivided  into  two  parts  by  a  diagonal  line 
directed  downwards,  forwards,  and  outwards.  The  upper  and  outer 
part  gives  origin  to  the  semimembranosus,  and  the  lower  and  inner,  to 
the  conjoined  long  head  of  the  biceps  and  semitendinosus.  The 
inferior  portion,  which  is  in  line  with  the  inner  margin  of  the  ramus, 
is  rough  and  triangular,  and  gives  origin  to  fibres  of  the  adductor 
magnus.  The  external  surface  is  situated  between  the  outer  and 
anterior  borders,  and  supports  the  obturator  externus.  The 
internal  surface  is  placed  between  the  inner  and  anterior  borders. 
It  looks  towards  the  ischio-rectal  fossa,  and  gives  origin  to  fibres 
of  the  obturator  internus. 

The  ramus  is  the  compressed  portion  which  extends  upwards 
and  inwards,  from  the  tuberosity,  on  the  anterior  aspect  of  the 
obturator  foramen,  where  it  joins  the  inferior  pubic  ramus,  the 
place  of  meeting  being  indicated  externally  by  a  rough  ridge. 
The  outer  border  is  sharp  for  a  portion  of  the  obturator  membrane, 
and  forms  part  of  the  anterior  margin  of  the  obturator  foramen. 
The  inner  border  is  thick,  and  anteriorly  it  is  rough  and  everted, 
more  so  in  the  male  than  in  the  female,  for  the  attachment 
of  the  fascia  of  Colles,  crus  penis,  and  ischio-cavernosus  muscle. 
In  the  female  this  part  gives  attachment  to  the  crus  clitoridis  and 
erector  clitoridis.  Elsewhere  the  inner  border  gives  attachment 
to  the  triangular  ligament  and  compressor  urethra.  The  outer 
surface  gives  origin,  from  within  outwards,  to  portions  of  the 
adductor  magnus  and  obturator  externus.  The  inner  or  pelvic 
surface  gives  attachment  to  part  of  the  obturator  internus  and 
j>arietal  pelvic  fascia.  At  its  lower  part,  near  the  inner  border, 
there  is  a  sharp  ridge  which  gives  attachment  to  the  falciform 
process  of  the  great  sacro-sciatic  ligament. 

The  OS  pubis  lies  in  the  anterior  wall  of  the  pelvis,  and  is 
composed  of  a  body  and  two  rami,  superior  and  inferior.  The 
body  is  compressed  from  before  backwards,  and  occupies  an 
oblique  plane,  which  is  directed  downwards  and  backwards.  It 
presents  three  surfaces — anterior,  posterior,  and  internal.  The 
anterior  or  femoral  surface  has  an  inclination  downwards.  At  its 
upper  and  inner  part,  below  and  external  to  the  pubic  angle,  it  gives 
origin  to  the  adductor  longus,  and,  lower  down,  to  the  following 
muscles,  in  order  from  within  outwards — gracilis,  adductor  brevis, 
a  small  portion  of  the  adductor  magnus,  and  obturator  externus. 
The  posterior  or  pelvic  surface  has  an  inclination  ujjwards,  and 
gives  attachment  from  without  inwards  to  the  obturator  internus. 


2o8  A  MANUAL  OF  ANATOMY 

parietal  pelvic  fascia,  levator  ani,  and  pubo-prostatic  ligament. 
The  infernal  SKrface  is  oval,  and  occupies  an  oblique  plane,  which 
is  directed  do\\Tiwards  and  backwards.  It  is  covered  by  cartilage, 
and  articulates  ^^ith  its  fellow  to  form  the  s^•mphysis  pubis,  a  plate 
of  fibro-cartilage  intervening. 

The  borders  are  external  and  superior.  The  external  border, 
which  is  sharp,  looks  into  the  obturator  foramen,  and  gives  attach- 
ment to  part  of  the  ohtiu-ator  membrane.  The  su-perior  border 
or  crest  is  thick,  and  about  an  inch  long.  At  its  outer  extremity  is 
the  -puhic  spine,  which  may  be  blunt  or  sharp,  for  the  attach- 
ment of  Poupart's  ligament,  and  internalh'  is  the  pubic  angle, 
which  surmounts  the  internal  surface.  The  crest  gives  attachment 
to  the  conjoined  tendon,  pyramidalis,  and  outer  head  of  the  rectus 
abdominis. 

The  inferior  ramus  passes  downwards  and  outwards,  and  corre- 
sponds in  all  respects  \\'ith  the  ischial  ramus,  which  it  joins.  Its 
anterior  surface  gives  origin,  from  within  outwards,  to  the  gracilis, 
adductor  brevis.  adductor  magnus.  and  obturator  extemus.  The 
structiu'es  attached  to  the  posterior  surface  are  portions  of  the 
obturator  internus  and  parietal  pelvic  fascia. 

The  superior  ramus  extends  outwards  and  upwards  from  the 
body  to  the  iho  -  pectineal  eminence  and  anterior  part  of  the 
acetabulum,  of  which  latter  it  forms  one-fifth.  It  hes  above  the 
obturator  foramen,  and  is  triangular.  Superiorly,  at  the  back 
part,  is  a  prominent  ridge,  representing  the  pectineal  portion  of  the 
ilia -pectineal  line,  which  leads  to  the  pubic  spine,  and  gives  attach- 
ment to  the  following  structures  :  the  pubic  lamina  of  the  fascia 
lata,  pectineus,  Gimbemat's  ligament,  and  conjoined  tendon. 
In  front  of  this  line  is  the  superior  or  pectineal  surface,  which  is  sloped 
downwards  and  fonvards,  and  is  triangular.  It  supports  the 
pectineus,  and  is  limited  antero-inferiorly  by  the  obturator  crest, 
which  extends  from  the  pubic  spine  to  the  anterior  margin  of  the 
cotyloid  notch.  The  inferior  surface  presents  the  obturator  groove 
for  the  obturator  vessels  and  nerve,  the  direction  of  which  is  do^\^l- 
wards,  fonvards,  and  inwards.  The  posterior  surface  gives  partial 
origin  to  the  obturator  internus. 

The  acetabulum  or  cotyloid  cavity  is  situated  on  the  outer  surface 
of  the  bone,  and  is  directed  downwards,  outwards,  and  forwards. 
It  is  deep  and  circular,  and  articulates  ^^dth  the  head  of  the  femur. 
The  ischium  forms  rather  more  than  two-fifths  of  it,  the  ihum 
rather  less,  and  the  os  pubis  the  remaining  fifth.  It  is  siurmounted 
by  a  prominent  brim,  upon  which  the  cotjioid  ligament  is  set,  except 
at  the  anterior  and  inferior  part,  where  there  is  the  cotyloid  notch, 
this  being  bridged  over  b}^  the  cotyloid  and  transverse  ligaments. 
The  capsular  ligament  is  attached  to  the  bone  just  outside  the  brim. 
The  interior  is  di\-ided  into  two  parts  —  articular  and  non- 
articular.  The  articular  portion  is  covered  by  cartilage,  which 
is  arranged  in  the  form  of  a  horseshoe,  and  surrounds  the  circum- 
ference, except  opposite  the  cotj-loid  notch.    The  non- articular  part. 


THE  BONES  OF  THE  LOWER  LIMB 


209 


which  is  formed  mainly  by  the  ischium,  is  depressed,  and  lodges 
the  Haversian  gland  of  the  hip-joint. 

The  obturator  or  thyroid  foramen  hes  below,  and  internal  to,  the 
acetabulum,  its  boundaries  being  formed  by  the  ischium  and  os 
pubis.  Its  long  diameter  is  directed  downwards  and  outwards, 
and  it  is  oval  in  the  male,  but  triangular,  with  rounded  angles,  in 
the  female.  Its  circumference  is  sharp  for  the  obturator  membrane, 
which  closes  the  opening,  except  opposite  the  obturator  groove 
superiorlv,  where  it  converts  that  groove  into  a  fibro-osseous  canal. 

The  great  and  small  sciatic  notches  are  situated  on  the  posterior 
border  of  the  bone,  and  are  separated  from  each  other  b\'  the  spine 
of  the  ischium.  The  great  notch  is  formed  partly  by  the  ilium, 
and  partlv  bv  the  ischium;  and  the  sm.cH  notch  lies  between  the 
ischial  spine  and  tuber  ischii. 

In  the  recent  state  these  notches  are  converted  into  foramina  by 
the  great  and  small  sacro-sciatic  ligaments.  For  the  structures  which 
pass  through  these  foramina,  see  the  description  of  the  gluteal  region. 


Appears  about  the  8th  Week 
(intra-uterine) 


Appears  about  the  5th  Month 
(intra-uterine) 


Appears  about  the  3rd  Month 
(intra-uterine) 


Fig.  129. — Ossification  of  the  Os  Inxomixatum. 

The  os  innominatum  is  pierced  by  a  great  number  of  nutrient 
foramina  for  arteries,  the  chief  of  which  are  situated  as  follows: 
along  the  inner  aspect  of  the  crest  for  branches  of  the  deep  cir- 
cumflex iliac;  in  the  iliac  fossa  near  the  auricular  surface,  where 
there  are  one  or  two  for  branches  of  the  ilio-lumbar;  on  the  external 
surface  of  the  ihum,  and  around  the  margin  of  the  acetabulum 
for  branches  of  the  gluteal;  between  the  acetabulum  and  tuber 
ischii  for  branches  of  the  obturator;  on  the  ilio- pectineal  eminence 
for  branches  of  the  deep  circumflex  iliac;  and  over  the  body  of  the 
OS  pubis  for  branches  of  the  obturator,  and  of  the  pubic  branches 
of  the  common  femoral. 

Articulations. — Posteriorly  with  the  sacrum,  externally  with  the 
femur.  ;ind  internally  with  its  fellow. 

Ossification. — -The  os  innominatum  is  ossified  in  cartilage  from  3  primary 
and  9  secondary  centres.  The  primary  centres  are  iliac,  ischial,  and  pubic. 
The  iliac  centre  aj^p'-ar-,  in  the  Sth  week  ;  the  ischial  centre  in  the  3rd  month  : 
and  th<;  pubic  centre  in  the  ^th  niunth  in  the  superior  pubic  ramus. 

The  ischial  and  inferior  pubic  rami  join  about  the  Hth  year. 

14 


A   MANUAL  OF  ANATOMY 


Acetabulum. — The  superior  pubic  ramus  is  shut  out  from  this  cavity  for 
some  time  by  a  triangular  portion  of  cartilage,  called  the  pars  acetabularis. 
From  its  apex  there  is  prolonged  backwards  a  strip  of  cartilage  [ilio-ischial) . 
The  entire  cartilage  resembles  the  letter  Y,  laid  on  its  side.  The  open  part 
of  the  Y  is  directed  forwards,  and  forms  the  pars  acetabularis.  The  Y  cartilage 
has  3  secondary  centres.  One,  called  the  acetabular  centre,  appears  in  the 
i2th  year  in  the  pars  acetabularis,  and  ossification  is  completed  by  the  iA,th 
year.  It  then  forms  a  distinct  bone,  called  the  os  acetabuli,  which  joins  the 
superior  pubic  ramus  about  the  i6th  year. 

Appears  about  the  15th  Year, 
and  joins  about  25 


Appears  about  the  15th  Year 
and  joins  about  25 


Represents  the 

Os  Acetabuli 

Appears  about  the  15th  Year, 
and  joins  about  25 


Appear  about  the  12th  Year, 
and  join  about  18 


t/ Appears  about  the  15th  Year, 

and  joins  about  25 


Join  in  the  8th  Year 

Fig.   130. — Ossification  of  the  Epiphyses  of  the  Os  Innominatum. 


The  other  two  secondary  centres  for  the  Y  cartilage  appear  about  the  14th 
year,  one  of  them  in  the  ilio-ischial  strip  or  stem  of  the  Y;  and  the  other  at 
the  meeting  of  the  two  limbs  and  stem  of  the  Y.  The  ossification  of  the 
bottom  of  the  acetabulum  is  completed  from  the  16th  to  the  iWi  year. 

Other  Secondary  Centres. — These  are  as  follows :  (i)  One  for  the  crest,  one  for 
the  anterior  inferior  iliac  spine,  one  (a  thin  scale)  for  the  surface  of  the  tuber 
ischii,  and  one  for  the  spine  of  the  ischium,  each  of  these  centres  appearing 
about  the  i$th  year  ;  (2)  one  for  the  pubic  spine,  and  one  for  the  pubic  angle, 
each  of  these  two  centres  appearing  about  the  iSth  year.  These  epiphyses 
usually  join  about  the  2Kth  year. 


The  Pelvis. 

The  pelvis  is  formed  by  the  ossa  innominata,  sacrum,  and 
coccyx,  the  hip-bones  constructing  the  anterior  and  lateral  walls, 
whilst  the  sacrum  and  coccyx  lie  in  the  posterior  wall.  It  is 
divided  into  two  parts,  called  false  pelvis  and  true  pelvis,  the 
division  being  effected  by  a  plane  passing  through  the  upper  border 
of  the  sj^mphysis  pubis,  ilio-pectineal  line,  and  sacral  promontory. 

The  false  pelvis,  which  lies  above  this  plane,  is  formed  by  the 
iliac  fossae,  and  constitutes  a  part  of  the  abdomen  proper. 

The  true  pelvis  is  situated  below  the  plane  referred  to,  and  pre- 
sents a  brim  or  inlet,  a  cavity,  and  an  outlet.  The  brim  is  formed 
in  front  by  the  upper  border  of  the  symphysis  pubis,  behind  by  the 


THE  BONES  OF  THE  LOWER  LIMB  211 

sacra)  promontory,  and  between  these  two  points  by  the  following 
parts  from  before  backwards— the  angle,  crest,  and  spine  of  the 
OS  pubis,  the  ilio-pectineal  line,  and  the  antero-inferior  border  of 


Fig.  131. — The  Male  Pelvis. 


Fig.   132. — The  Female  Pelvls. 


the  ala  of  the  sacrum.  In  the  male  it  is  cordate,  the  base  of  the 
heart  which  js  encroached  upon  by  the  sacral  promontory,  being 
directed  backwards.     In  the  female  it  is  oval,  the  long  diameter 

14—2 


212  A   MANUAL  OF  ANATOMY 

being  transverse.  The  diameters  of  the  brim  are  antero-posterior 
or  conjugate,  transverse,  right  obliqtie,  and  left  oblique.  The  antero- 
posterior or  conjugate  diameter  extends  from  the  upper  border  of 
the  symphysis  pubis  to  the  sacral  promontory  ;  the  transverse, 
from  one  ilio-pectineal  line  to  the  opposite,  across  the  widest  part 
of  the  brim ;  and  the  oblique,  from  one  sacro-iliac  articulation  to 
the  ilio-pectineal  eminence  of  the  opposite  side.  The  oblique 
diameters  are  called  right  and  left  from  the  sacro-iliac  articulations 
whence  they  extend. 

The  cavity  is  bounded  in  front  by  the  bodies  and  rami  of  the 
pubic  bones,  behind  by  the  sacrum  and  coccyx,  and  laterally 
b}''  an  extensive  osseous  plane,  formed  chiefly  by  the  pelvic  surface 
of  the  ischium,  but  also  by  that  of  the  ilium,  and  terminating 
below  in  the  incurved  ischial  spine.  It  is  shallow  in  front,  where 
its  depth  is  from  i|  to  2  inches,  but  deep  behind,  where  it  measures 
about  5^  inches,  following  the  curve  of  the  sacrum.  The  plane 
of  the  anterior  wall  is  oblique,  being  directed  downwards  and 
backwards.  The  posterior  wall  is  curved,  and  at  its  upper  part 
looks  mainly  downwards.  The  lateral  wall  is  divided  into  two 
parts  by  an  indistinct  line  extending  downwards  and  backwards 
from  the  ilio-pectineal  eminence  to  the  spine  of  the  ischium. 
These  parts  are  spoken  of  as  the  anterior  and  posterior  inclined 
planes  of  the  ischium,  the  anterior  looking  slightly  forwards  and 
the  posterior  slightly  backwards.  The  conjugate  diameter  of  the 
cavity  extends  from  the  centre  of  the  symphysis  pubis  to  the 
upper  margin  of  the  third  sacral  segment ;  the  transverse,  from 
a  point  corresponding  to  the  lower  margin  of  the  acetabulum 
on  one  side  to  the  corresponding  point  on  the  other  ;  and  the 
oblique,  from  the  centre  of  the  great  sacro-sciatic  foramen  on 
one  side  to  the  centre  of  the  obturator  membrane  on  the  other. 

The  outlet  presents  three  prominences,  namely,  the  tuber  ischii  at 
either  side,  and  the  tip  of  the  coccyx  in  the  median  line  posteriorly. 
Its  boundaries,  at  either  side  from  before  backwards,  are  as  follows  : 
the  lower  border  of  the  symphysis  pubis,  inferior  ramus  of  os  pubis, 
ramus  of  ischium,  tuber  ischu,  great  sacro-sciatic  ligament  in  the 
recent  state,  and  tip  of  the  coccyx.  In  front  of  an  imaginary  line 
connecting  the  ischial  tuberosities  is  the  subpubic  arch,  which  is 
bounded  at  either  side  by  the  ischio-pubic  ramus,  and  above  by 
their  meeting  to  form  the  siibpubic  angle.  The  arch  is  occupied 
by  the  triangular  ligament  of  the  urethra,  and  its  plane  is  directed 
downwards  and  backwards.  The  conjugate  diameter  of  the  outlet 
extends  from  the  lower  border  of  the  symphysis  pubis  to  the  tip 
of  the  coccyx,  the  transverse  from  one  tuber  ischii  to  the  other,  and 
the  oblique  from  the  middle  of  the  lower  border  of  the  great  sacro- 
sciatic  ligament  on  one  side  to  the  place  of  union  between  the 
inferior  pubic  and  ischial  rami  on  the  other. 

The  Inclination  of  the  Pelvis. — In  the  erect  posture  the  plane  of 
the  pelvic  brim  forms  with  the  horizontal  an  angle  of  from  50  to 
60  degrees,  and  the  base  of  the  sacrum  is  about  3I  inches  above  the 


THE  BONES  OF  THE  LOWER  LIMB  213 

upper  border  of  the  symphysis  pubis.  The  brim  is  therefore  directed 
upwards  and  forwards.  An  idea  of  this  obhquity  may  be  obtained 
by  placing  a  pelvis  against  a  wall  in  such  a  way  that  the  anterior 
superior  iliac  spines  and  the  upper  border  of  the  symphysis  pubis 
will  touch  the  wall  so  as  to  lie  in  the  same  vertical  plane.  A  line 
connecting  the  tip  of  the  coccyx  with  the  lower  border  of  the 
symphysis  pubis  forms  with  the  horizontal  an  angle  of  about  11 
degrees,  and  the  tip  of  the  coccyx  is  about  f  inch  above  the  sub- 
pubic angle.  The  direction  of  the  outlet  is  downwards  and  back- 
wards, principally  downwards  when  the  coccyx  is  extended.  The 
plane  of  the  symphysis  pubis  forms  with  the  horizontal  an  angle 
of  from  35  to  40  degrees.  It  is  worthy  of  note  that  the  sacro- 
vertebral  angle  is  estimated  at  117  degrees  in  the  male,  and  as 
much  as  130  in  the  female. 

Tne  Axes  of  the  Pelvis. — The  axes  represent  imaginary  lines 
intersecting  the  planes  of  the  brim,  cavity,  and  outlet  at  right  angles 
through  their  central  points.  The  axis  of  the  brim  corresponds 
with  a  line  drawn  from  the  umbilicus  to  the  sacro-coccygeal  articu- 
lation, and  its  direction  is  downwards  and  distinctly  backwards. 
The  axis  of  the  outlet  represents  a  line  drawn  from  the  sacral 
promontory  through  the  centre  of  the  outlet,  and  its  direction  is 
downwards  and  very  slightly  backwards.  The  axis  of  the  cavity 
intersects  planes  having  different  inclinations,  and  is  necessarily 
curved,  the  concavity  being  directed  forwards.  It  is  described  as 
'  the  perpendicular  of  a  line  drawn  from  the  middle  of  the  symphysis 
pubis  to  the  centre  of  the  sacro-coccygeal  curve.'  The  average 
measurements  of  the  axes  of  the  female  pelvis  are  as  follows  : 

Brim 

Cavity 
Outlet 

Sexual  Differences. — The  differences  in  the  two  sexes  are  as 
follows  : 

Female.  Male. 

Bones  smoother  and  more  slender.  Rones  rougher  and  more  massive 

Acetabula  wide  apart.  Acetabula  not  so  wide  apart. 

True  pelvis  wider  and  shallower.  True  pelvis  narrower  and  deeper. 

Obturator  foramen  triangular.  Obturator  foramen  oval. 

Ischial  tuberosities  wider  apart  and  Ischial  tuberosities  not  so  wide  apart 

everted.  and  inverted. 

Span  of  subpubic  arch  wide.  Span  of  subpubic  arch  narrow. 

Inner   border  of  ischio-pulnc   ramus  Inner   border  of    ischio-pubic  ramus 

comparatively  smootli.  strongly  marked  and  everted. 

Brim  transversely  oval.  Brim  cordate. 

Ilia  more  vertical.  Iha  less  vertical. 

False  pelvis  narrower.  False  pelvis  wider. 

Sacral  promontory  less  projecting.  Sacral  promontory  more  projecting. 

Sacrum       broader,       shorter,       and  Sacrum  narrower,  longer,  and  more 

straighter.  curved. 

Coccyx     more    movably   articulated  Coccyx     less     movably    articulated 

with  sacrum.  with  sacrum. 

Symphysis  pubis  shallower.  Symphysis  pubis  deeper. 


Conjugate. 

Transverse. 

Oblique. 

4i 

Si 

5 

5 

5 

5i 

5 

4? 

4S 

214  A   MANUAL  OF  ANATOMY 

The  Pelvis  of  the  Child. — The  pelvis  is  of  small  size  in  the  child. 
The  iliac  alae  are  expanded,  and  the  cavity  is  of  small  dimensions, 
so  that  a  large  part  of  the  urinary  bladder  in  both  sexes  lies  in 
the  hypogastric  region  of  the  abdomen.  The  sacro-vertebral  angle 
is  relatively  greater,  and  the  pelvis  has  consequently  a  greater 
inclination. 

Varieties  of  Pelvis. — The  proportion  of  the  antero-posterior  diameter  to  the 
transverse  is  the  pelvic  index.  Pelves  having  an  index  above  95  are  called 
dolichopellic,  from  95  to  90  wiesatipellic,  and  below  90  platypellic. 

The  Femur. 

The  femur  extends  from  the  hip  to  the  knee,  its  direction 
being  downwards,  inwards,  and  slightly  backwards.  It  is  a  long 
bone,  and  is  divisible  into  a  shaft  and  two  extremities,  upper  and 
lower. 

The  upper  extremity  presents  a  head,  neck,  and  two  trochanters, 
great  and  small,  together  with  anterior  and  posterior  intertro- 
chanteric lines.  The  head  forms  more  than  half  a  sphere,  and 
its  direction  is  upwards,  inwards,  and  slightly  forwards.  Its 
surface  is  smooth  and  covered  by  cartilage,  except  at  a  point 
behind  and  below  the  centre,  where  it  presents  a  rough  depression. 
The  ligamentum  teres  is  attached  to  the  upper  part  of  this  depres- 
sion, which  presents  a  small  foramen  for  the  passage  of  a  nutrient 
artery.  The  head  encroaches  more  upon  the  upper  surface  of  the 
neck  than  on  the  under. 

The  neck  forms  with  the  shaft  an  angle  of  about  125  degrees  on 
an  average,  the  range  being  from  no  to  140.  It  is  greater  in  the 
male  than  in  the  female.  The  direction  of  the  neck  is  upwards, 
inwards,  and  slightly  forwards.  It  is  expanded  at  either  extremity, 
especially  towards  the  shaft,  and  it  presents  four  aspects — anterior, 
posterior,  superior,  and  inferior,  of  which  the  posterior  and  inferior 
are  more  extensive  than  the  other  two.  The  anterior  aspect  is  on 
the  same  plane  with  the  anterior  surface  of  the  shaft,  from  which 
it  is  separated  by  the  anterior  intertrochanteric  line.  This  line 
passes  downwards  and  inwards,  and  it  presents  at  either  extremity 
the  superior  cervical,  and  inferior  cervical,  tubercle.  The  anterior 
intertrochanteric  line  gives  attachment  along  its  cervical  aspect 
to  the  anterior  part  of  the  capsular  ligament  of  the  hip- joint, 
including  the  ilio-femoral  band.  Its  inferior  relations  are  the 
vastus  externus  over  about  the  upper  third,  and  the  crureus  over 
about  the  lower  two-thirds.  The  anterior  aspect  of  the  neck  is 
entirely  intracapsular,  and  is  more  or  less  ridged,  being  closely 
covered  by  the  retinacula  of  the  capsular  ligament.  The  posterior 
aspect  is  of  greater  extent  than  the  anterior,  and  is  smooth  and 
concave.  It  is  separated  from  the  shaft  by  the  posterior  inter- 
trochanteric line,  which  presents  at  its  junction  with  the  posterior 
border  of  the  great  trochanter  the  q^iadrate  ttibercle,  whence  the 
Imea  quadrati,  for  the  quadratus  femoris  muscle,  descends.     Only 


THE  BONES  OF  THE  LOWER  LIMB 


215 


Obturator  Interims  and  Genielji  Anterior  Intertrochanteric  Line 

Pynformis         .  '  K^^ 

'  I         /^         I    ^\  .  IJepres  ion  for  Ligamentun 

\        I  '.       r  !        \    .-"  Teres 


Gluteus  jMininiiisr 


Vastus  Exteriui 


Crureus 


Neck 

Ilio-psoas 

Small  Trochanter 

Vastus  Internus 


External  Tuberosity  -- 
on  Kxternal  Condyle 


--*'  Subcrureus 


(Xt'ductor  Tubercle 


_Tendon  of  Adductor  Magnus 


Internal  Tuberosity 
on  Internal  Condyle 


Patellar  Surface 

^'•c;-   133- — fi'ii  KiGHT  Femur  (Anterior  View), 


2i6  A  MANUAL  OF  ANATOMY 

the  upper  two-thirds  of  this  aspect  are  intracapsular  and  covered 
by  retinacula,  the  capsular  ligament  being  very  loosely  attached 
along  the  junction  of  the  middle  and  lower  thirds.  The  lower 
third  is  therefore  extracaps^dar,  and  at  its  outer  part  it  presents  a 
horizontal  groove  which  leads  to  the  digital  or  trochanteric  fossa, 
and  lodges  the  tendon  of  the  obturator  externus.  The  siiperior 
aspect  forms  a  short,  almost  horizontal  border,  which  has  a  slight 
inclination  downwards  to  the  great  trochanter.  The  inferior 
aspect  forms  a  long,  concave  border,  ending  interiorly  at  the  small 
trochanter. 

The  neck  is  pierced  by  numerous  nutrient  foramina,  which  are 
more  abundant  and  of  larger  size  above  and  behind  than  else- 
where. 

The  head  and  neck  receive  their  blood-supply  from  the  obturator^ 
sciatic,  and  external  and  internal  circumflex,  arteries. 

The  great  trochanter  is  a  quadrilateral  eminence  continuous  with 
the  outer  surface  of  the  shaft.  It  presents  three  surfaces  and  four 
borders.  The  external  surface  is  marked  by  an  oblique  impression 
which  extends  from  the  postero-superior  to  the  ante  o-inferior 
angle,  and  gives  insertion  to  the  gluteus  medius.  The  anterior 
surface  presents,  towards  its  lower  part,  an  impression  for  the 
insertion  of  the  gluteus  minimus.  The  internal  surface  at  its  lower 
part  presents  the  digital  or  trochanteric  fossa  for  the  insertion  of 
the  obturator  externus,  whilst  above  and  in  front  of  this  it  affords 
insertion  to  the  obturator  internus  and  gemelli.  The  superior 
border,  which  is  almost  horizontal,  meets  the  posterior  border  at 
a  right  angle,  the  pointed  projection  thus  formed  being  called  the 
postero-superior  angle.  Near  the  centre  of  this  border  there  is  an 
oval  impression  for  the  insertion  of  the  pyriformis.  The  inferior 
border  gives  origin  to  fibres  of  the  vastus  externus.  The  anterior 
border  skirts  the  front  of  the  great  trochanter,  and  ends  above  at 
the  superior  cervical  tubercle.  It  also  gives  origin  to  fibres  of  the 
vastus  externus.  The  posterior  border  is  prominent  and  con- 
tinuous with  the  posterior  intertrochanteric  line,  the  quadrate 
tubercle  being  situated  at  the  junction  of  the  two.  The  great 
trochanter  is  pierced  by  several  nutrient  foramina. 

The  small  trochanter  is  a  conical  projection  which  springs  from 
the  posterior  and  inner  aspects  of  the  bone  where  the  neck  and 
shaft  join.  It  gives  insertion  to  the  ilio-psoas,  some  of  the  fibres 
of  the  iliacus  being  inserted  below  and  in  front  of  it,  where  there 
is  a  depressed  triangular  surface  lying  between  the  prominence 
and  the  spiral  line. 

The  trochanters  receive  their  blood-supply  from  the  circumflex 
arteries. 

The  shaft  is  longitudinally  curved,  the  convexity  being  directed 
forwards.  Its  girth  is  least  at  the  centre,  and  it  expands  at 
either  end,  more  especially  the  lower.  It  is  triangular  in  section 
in  the  middle  third,  the  lateral  angles  being  rounded  off,  and  the 
posterior,  formed  by  the  linea  aspera,  prominent.     Over  its  upper 


THE  BONES  OF  THE  LOWER  LIMB 
Head,  Neck 


217 


Depression  for 
Ligamentum  Teres 


Quadratus  Femoris A 


Ilio-psoas 

Small  Trochanter  


Portion  of  Iliacus 

Pectineut 

Spiral  Line 

Adductor  Brevis 


Vastus  Internus- 


Adductor  Longus.] 


Inner  Lip  of  Linea  Aspera 

Adductor  Magnus 


Internal  Supracondylar 
Ridge  and  Expansion  from  Tendon  — 
of  Adductor  Magnus 


Adductor  Tubercle 
and  Adductor  Magnus 


Internal  Head  of- 

Gastrocnemius 


Internal  Tuberosity' 

Internal  Condyle 


.  L)igital  Fossa  and  Obturator  Externus 
I  Quadrate  Tubercle 


Gluteus  Medi'.is 
Great  Trochanter 


Gluteal  Ridge  and 

Gluteus  Maximus 


Medullary  Foramen 

Vastus  Externus 


Summit  of  Linea  Aspera 
Outer  Lip  of  Linea  Aspera 


Crureus 

Femoral  Head  of  Biceps 


External  Supracondylar  Ridge 


Popliteal  Surface 

_  -    Plantaris 

_  .    External  Head  of  Gastrocnemius 
External  Tuberosity 
External  Condyle 


Intercondylar  Fossa 

Fig.   1 34. —The  Right  Femur  (Posterior  View), 


2i8  A   MANUAL  OF  ANATOMY 

and  lower  thirds  it  is  somewhat  subcyHndrical.  The  posterior 
aspect  presents  over  its  middle  third  a  bold  ridge,  called  the  linea 
aspera,  which  has  two  lips,  outer  and  inner,  and  a  narrow  inter- 
vening space.  The  outer  lip  gives  attachment,  from  behind  forwards, 
to  the  short  head  of  the  biceps,  external  intermuscular  septum, 
vastus  externus  over  its  upper  half,  and  crureus  over  its  lower 
half.  The  inner  lip  gives  attachment,  from  behind  forwards, 
to  the  adductor  magnus,  adductor  longus,  internal  intermuscular 
septum,  and  vastus  internus.  A  little  above  the  centre  of  the  shaft, 
close  to  the  inner  lip,  is  the  medullary  foramen  for  a  branch  of  the 
second,  or  third,  perforating  artery,  the  direction  of  the  foramen 
and  the  canal  to  which  it  leads  being  upwards  towards  the  head. 

Over  the  upper  third  of  the  shaft  the  lips  of  the  linea  aspera  diverge. 
The  outer  lip  is  prolonged  to  the  base  of  the  great  trochanter  pos- 
teriorlyj  and  over  about  its  lower  3  inches  it  is  conspicuously  rough, 
this  portion  being  known  as  the  gluteal  ridge,  which  gives  insertion 
to  the  lower  part  of  the  gluteus  maximus.  Close  to  the  outer  side 
of  this  ridge  the  vastus  externus  takes  origin,  and  close  to  its  inner 
side  the  upper  fibres  of  the  adductor  magnus  take  insertion.  The 
inner  lip  bifurcates.  One  division  is  prolonged  in  a  winding  manner 
round  the  inner  aspect  of  the  shaft,  passing  in  front  of  the  small 
trochanter  and  terminating  at  the  inferior  cervical  tubercle,  where 
it  passes  into  the  anterior  intertrochanteric  line.  This  winding 
division  is  called  the  spiral  line,  and  it  gives  origin  to  the  upper 
fibres  of  the  vastus  internus.  The  other  division  is  prolonged  to  the 
back  of  the  small  trochanter,  and  it  gives  insertion  over  its  upper 
third  to  the  pectineus,  and  over  its  whole  extent  to  the  adductor 
brevis,  the  latter  being  behind  the  former.  The  relation  of  muscles 
at  the  back  of  the  upper  end  of  the  shaft,  from  the  small  trochanter 
outwards  to  the  outer  margin  of  the  gluteal  ridge,  is  as  follows  : 
ilio-psoas ;  pectineus ;  adductor  brevis ;  lower  fibres  of  quadratus 
femoris  ;  adductor  magnus  ;  gluteus  maximus ;  and  vastus  externus. 
The  narrow  intervening  space  of  the  linea  aspera  between  its  two 
lips  is  in  line  with  the  linea  quadrati, above. 

Over  the  lower  third  of  the  shaft  the  lips  of  the  linea  aspera 
diverge  widely,  and  are  prolonged  to  the  condyles  as  the  external  and 
internal  supracondylar  ridges.  These  enclose  between  them  a  flat 
triangular  area,  called  the  popliteal  surface,  which  is  also  known  as 
the  trigonum  femoris.  Over  this  region  the  periosteum  is  very  thin, 
and  this  part  of  the  bone  is  predisposed  to  necrotic  changes.  The 
popliteal  surface  forms  the  upper  part  of  the  floor  of  the  popliteal 
space.  The  external  siipracondylar  ridge  gives  attachment  over  its 
whole  extent  to  the  external  intermuscular  septum,  and  over  about 
its  upper  two-thirds  to  the  short  head  of  the  biceps  and  the  crureus. 
For  a  short  distance  below,  it  gives  origin  to  the  plantaris,  and 
immediately  external  to  this,  to  fibres  of  the  outer  head  of  the  gastroc- 
nemius. The  internal  supracondylar  ridge  is  interrupted  about  an 
inch  below  its  commencement  by  a  slight  groove,  which  is  produced 
by  the  femoral  vessels,  and  at  its  lower  extremity,  close  to  the  interna], 


THE  BONES  OF  THE  LOWER  LIMB 


219 


condyle,  there  is  a  projection  called  the  adductor  tubercle,  for  the 
insertion  of  the  tendon  of  the  adductor  magnus.  Superiorly,  for 
about  an  inch,  this  ridge  gives  insertion  to  a  portion  of  the  adductor 
magnus.  and  below  the  femoral  groove  to  an  expansion  from  its 
tendon. 

The  shaft  presents  three  surfaces,  anterior  and  two  lateral, 
but  these  merge  gradually  into  one  another,  except  posteriorly  in 
the  situation  of  the  linea  aspera  over  the  middle  third.  The 
anterior  and  external  surfaces  over  about  their  upper  three-fourths 
give  origin  to  the  crureus.  The  internal  surface  is  non-musc  ilar, 
and  presents  a  characteristic  elongated  bare  strip,  which  is  merely 
covered  by  the  vastus  internus.  The  lower  fourth  of  the  anterior 
surface  at  its  upper  part  gives  origin  to  the  subcrureus,  and  lower 


Patellar  Surface 


External  Tuberosity 


External  Condyle 


Internal  Tuberosity 


Internal  Condyle 
Patellar  Facet  (in  extreme  flexion) 


Intercondylar  Fossa 

Fig.   135. — The  Lower  Extremity  of  the  Right  Femur. 


down  is  covered  by  the  suprapatellar  bursa,  and  the  pouch  which 
the  synovial  membrane  of  the  knee-joint  sends  upwards  above  the 
];atellar  surface  of  the  bone. 

The  lower  end  of  the  shaft  jiresents  many  nutrient  foramina  for 
the  passage  of  branches  of  the  anastomotica  magna  of  the  super- 
ficial femoral,  and  th(;  articular  branches  of  the  ])opliteal,  arteries. 

The  lower  extremity  j)resents  an  extensive  articular  surface, 
which  is  divided  into  three  ])arts — anterior  or  patellar,  and  two 
postero-inferior  or  condylar.  All  three  surfaces  are  continuous  in 
front,  but  the  condylar  surfaces  are  widely  separated  behind  by  the 
intercondylar  fossa.  The  patellar  surface  is  trochlear,  and  presents 
a  vertical  groove  with  a  convexity  on  either  side.  The  groove  is  to 
the  inner  side  of  the  centre,  and  the  part  external  to  it  is  broader, 
more  prominent,  and  extends  higher,  than  the  internal  part.     The 


220  A   MANUAL  OF  ANATOMY 

upper  border  is  therefore  sloped  inwards  and  slightly  downwards.  The 
greater  forward  prominence  of  the  outer  part  of  the  surface  explains 
why  the  patella  is  inclined  inwards  in  extension  of  the  knee-joint. 

The  condyles  are  convex  from  before  backwards  and  from 
side  to  side.  Posteriorly  they  become  prominent,  and  on  this 
aspect  the  external  condyle  extends  a  little  higher  than  the  internal. 
As  viewed  from  below  the  external  condyle  is  broad  and  short, 
the  internal  being  long  and  narrow.  When  the  femur  is  held 
vertically  the  internal  condyle  projects  lower  down  than  the 
external,  and  this  brings  the  two  condyles  upon  the  same  horizontal 
plane  when  the  bone  occupies  its  natural  sloping  position.  The 
outer  border  of  the  external  condyle  is  very  nearly  in  the  same  line 
with  the  outer  border  of  the  patellar  surface,  and  the  outer  border 
of  the  internal  condyle  is  in  the  same  line  with  the  inner  border  of 
the  patellar  surface.  The  inner  border  of  the  internal  condyle  has 
a  convex  outline,  and  at  its  anterior  part  it  turns  outwards  to  the 
patellar  surface.  For  the  most  part  the  condyles  are  parallel, 
the  exception  being  the  front  part  of  the  internal  condyle,  which 
inclines  outwards  to  meet  the  patellar  surface. 

The  demarcation  between  the  condylar  surfaces  and  the  patellar 
surface  is  clearly  marked  at  either  side.  The  external  condyle 
is  separated  from  the  patellar  surface  by  a  slightly  elevated  line 
and  groove,  extending  outwards  and  slightly  forwards  from  the 
front  and  outer  part  of  the  intercondylar  fossa  to  the  outer  border 
of  the  cartilaginous  surface,  where  there  is  a  depression  which 
receives  the  anterior  part  of  the  external  semilunar  fibro-cartilage 
during  extension  of  the  knee-joint.  The  internal  condyle  is  separated 
from  the  patellar  surface  by  a  line  and  groove,  extending  from 
near  the  front  and  inner  part  of  the  intercondylar  fossa  forwards  and 
slightly  inwards  to  the  inner  border  of  the  cartilaginous  surface, 
at  a  point  about  i  inch  below  the  inner  end  of  the  upper  border  of 
the  patellar  surface.  At  this  latter  point  there  is  a  depression  which 
receives  the  anterior  part  of  the  internal  semilunar  fibro-cartilage 
during  extension  of  the  knee-joint.  The  line  and  groove  just 
referred  to  do  not  extend  quite  close  to  the  intercondylar  fossa. 
The  groove  subsides,  but  the  line  sweeps  backwards  in  a  curved 
manner  along  the  outer  part  of  the  inner  condylar  surface,  thus 
marking  off  a  narrow  semilunar  zone  from  the  general  tibial  surface. 
This  zone  lies  close  to  the  inner  part  of  the  intercondylar  fossa,  and 
is  known  as  the  patellar  facet.  In  extreme  flexion  of  the  knee- 
joint,  as  in  the  position  assumed  by  the  miner  when  at  work,  the 
patella  by  its  inner  vertical  zone  articulates  with  this  facet,  which 
may  be  called  the  miner's  facet. 

The  outer  surface  of  the  external  condyle  towards  the  back  part 
presents  the  external  tuberosity,  which  gives  attachment  to  the  long 
external  lateral  ligament  of  the  knee-joint.  Immediately  above 
and  behind  the  tuberosity  is  an  impression  for  the  outer  head  of  the 
gastrocnemius,  and  behind  and  below  it  there  is  a  groove,  called 
the  popliteal  groove,  which  is  directed  downwards  and  forwards. 


THE  BONES  OF  THE  LOWER  LIMB  221 

The  tendon  of  the  pophteus  arises  from  the  front  part  of  the  hori- 
zontal portion  of  the  groove,  and  it  is  lodged  in  the  groove  only 
when  the  knee  is  flexed. 

The  inner  surface  of  the  internal  condyle  presents  at  its  centre 
a  large  blunt  eminence,  called  the  internal  tuberosity,  for  the 
attachment  of  the  internal  lateral  ligament.  Posteriorly,  where 
the  internal  supracondylar  ridge  joins  the  internal  condyle,  the 
adductor  tubercle  is  situated,  and  the  line  of  origin  of  the  inner 
head  of  the  gastrocnemius  extends  almost  transversely  outwards 
from  this  tubercle  above  the  internal  condyle. 


Fig.  136. — Longitudinal  Section  through  the  Upper  End  of  the  Femur, 

SHOWING    THE    PRESSURE    LaMELL^    AND    TENSION    LaMELL^. 

The  markings  in  connection  with  the  intercondylar  fossa  are  for 
the  crucial  ligaments.  The  impression  for  the  anterior  crucial 
ligament  is  at  the  back  part  of  the  inner  surface  of  the  external 
condyle,  whilst  that  for  the  posterior  crucial  ligament  is  at  the  front 
part  of  the  outer  surface  of  the  internal  condyle,  and  adjacent 
portion  of  the  front  of  the  intercondylar  fossa.  At  the  front  of 
that  fossa  in  the  middle  line  the  ligamentum  mucosum  is  attached. 

Articulations. — Superiorly  with  the  acetabulum  of  the  os  inno- 
minatum,  and  inferioriy  with  the  head  of  the  tibia  below,  and  the 
patella  in  front. 


A  MANUAL  OF  ANATOMY 


Structure. — The  structure  is  that  of  a  long  bone.  The  marrow 
canal  extends  from  a  point  just  below  the  small  trochanter  to  the 
level  of  the  apex  of  the  trigonum  femoris.  Above  and  below  these 
points  the  bone  is  composed  of  cancellated  tissue,  except  externally, 
where  there  is  a  shell  of  compact  bone.  The  cancellated  tissue  at 
the  upper  extremity  has  its  lamellae  arranged  in  a  series  of  curves 
disposed  in  two  systems,  one  of  which  represents  the  pressure  lamellae, 
and  the  other  the  tension  lamellae.  The  pressure  lamellce  extend 
from  the  lower  part  of  the  neck  and  upper  part  of  the  shaft  internally 
in  a  radiating  manner,  some,  which  are  very  strong,  passing  inwards 
to  the  head,  whilst  others  pass  outwards  to  the  great  trochanter. 
The  tension  lamellce  are  disposed  almost  at  right  angles  to  the 
pressure  lamellae,  and  arch  upwards  and  inwards  from  the  outer 
aspect  of  the  shaft,  below  the  great  trochanter,  to  the  head  and 
lower  part  of  the  neck.  Additional  strength  is  afforded  by  an 
almost  vertically  disposed  plate  of  compact  bone,  called  the  calcar 
femorale,  which  runs  upwards  and  downwards  in  front  of,  and 
above,  the  small  trochanter,  and  lies  in  the  line  in  which  weight 
is  transmitted.  The  cancellated  tissue  at  the  lower  extremity  has 
its  lamellae  arranged  in  obliquely  decussating  lines  which  enclose 
somewhat  rectangular  meshes. 

Varieties. — (i)  The  gluteal  ridge  may  assunie  the  form  of  a  depression, 
called  the  fossa  hypotrochanterica.  (2)  There  may  be  a  third  trochanter, 
situated  at  the  upper  part  of  the  gluteal  ridge.      (3)  The  linea  aspera  may  be 

unduly  prominent  owing  to  muscular 
action,  this  condition  being  known  as 
the  pilastered  femur.*  (4)  A  pressure 
facet  is  sometimes  met  with,  as  in 
miners,  at  the  upper  end  of  the  front  of 
the  neck,  close  to  the  cartilage  of  the 
head,  with  which  it  is  continuous,  this 
facet  being  due  to  prolonged  mainten- 
ance of  the  flexed  posture. 

The  Femur  of  the  Female. — 

(i)  The  bone  is  smoother  than  in 
the  male.  (2)  The  angle  formed 
by  the  neck  with  the  shaft  is 
about  no  degrees.  (3 )  The  bones 
are  farther  apart  above,  more 
sloped  inwards,  and  nearer  to 
each  other  below,  than  in  the 
male. 

Ossification. — The  femur  ossifies  in 
cartilage  from  one  primary,  and  four 
secondary,  centres.  The  primary  centre 
appears  at  the  middle  of  the  shaft  in 
tfie  seventh  week  of  in tra-u ferine  life. 
The  centre  for  the  lower  extremity 
appears  just  before  birth  in  the  bottom 


ist  Year,  and  joins  at  19 
yl-.4th  Year,  and  joins  at  iS 
14th  Year,  and  joins  at  17 


|.l Appears  in  the  7th  Week 

*^'  (intra-uterine) 


Appears  just  before  birth, 
and  joins  at  20. 


Fig.   137. 


-Ossification  of  the 
Femur. 


*  A  pilaster  {pila,  a  pile  or  column)  is  a  square  column  set  within  a  wall, 
and  projecting  for  only  a  fourth  of  its  breadth. 


THE  BONES  OF  THE  LOWER  LIMB 


?.23 


of  the  intercondylar  fossa.  At  birth  the  shaft  is  ossified,  and  the  lower  epiphysis 
IS  showing  signs  of  ossilication,  but  the  three  upper  epiphyses  are  cartilaginous. 
The  centre  for  the  head  appears  in  the  first  year,  that  for  the  great  trochanter 
in  the  fourth  year,  and  that  for  the  small  trochanter  in  the  fourteenth  year. 
The  small  trochanter  joins  the  shaft  at  seventeen,  the  great  trochanter  at 
eighteen,  the  head  at  nineteen,  and  the  lower  epiphysis  at  twenty.  The  neck 
is  ossified  from  the  centre  for  the  shaft.  The  line  indicating  the  junction  of 
the  lower  epiphysis  and  shaft  cuts  the  adductor  tubercle  into  two,  one  portion 
belonging  to  the  lower  epiphysis,  and  the  other  to  the  shaft. 


The  Patella. 

The  patella,  rotula,  or  knee-cap,  is  situated  in  front  of  the  knee- 
joint,  where  it  articulates  with  the  patellar  surface  of  the  femur. 
It  is  originally  a  sesamoid  cartilage  developed  in  the  tendon  of 
the  quadriceps  extensor  cruris.  The  bone  is  triangular  with  the 
apex  downwards,  and  is  compressed  from  before  backwards.     The 


Superior  Border 


External  Border 


Vertical  Femoral  Facet 
(in  extreme  flexion) 


Anterior  Surface 


-Upper  Transverse 
Femoral  Facet 


Middle  do.,  do. 
__Lower  do.,  do. 

Li^anientuni  PatelleE 


Fig.   138. — The  Right  Patella. 
A,   .'\nterior  Surface ;  B,   Posterior  Surface. 

superior  harder  or  base  is  broad,  and  its  plane  is  inclined  forwards 
and  slightly  downwards.  It  gives  insertion  anteriorly  to  the 
rectus  femoris  and  crureus,  in  this  order  from  1  efore  backwards, 
and  posteriorly  it  is  covered  by  a  portion  of  the  synovial  mem- 
brane of  the  knee-joint.  The  lateral  borders  are  sloped  towards 
the  apex,  the  outer  being  at  first  rather  more  prominent  than  the 
inner.  The  outer  border  over  its  u])per  third  gives  insertion  to  a 
jKjrtion  ol  the  vastus  externus,  and  the  inner  over  its  upper  hall  U)  a 


224  ^  MANUAL  OF  ANATOMY 

portion  of  the  vastus  internus.  The  apex  is  blunt,  and,  together  with 
the  adjacent  marginal  parts,  gives  attachment  to  the  ligamentum 
patellae,  by  which  the  bone  is  connected  with  the  tubercle  of  the  tibia. 

The  anterior  surface,  which  is  slightly  convex,  is  vertically 
striated  and  covered  by  a  prolongation  of  the  tendon  of  the  quadri- 
ceps extensor  cruris.  It  is  perforated  by  numerous  nutrient  fora- 
mina, and  is  subcutaneous,  being  separated  from  the  integument 
by  the  prepatellar  bursa. 

The  posterior  surface  is  divided  into  two  parts — articular  and 
non-articular.  The  non- articular  part  represents  the  lower  fourth, 
and  is  rough  and  depressed.  It  lodges  a  collection  of  fat  covered 
by  synovial  membrane.  The  articvilar  part  corresponds  with  the 
upper  three-fourths,  and  is  divided  into  two  unequal  parts  by  a  round 
vertical  ridge,  which  is  received  into  the  groove  of  the  patellar 
surface  of  the  femur.  The  external  division  is  broad  and  concave 
from  side  to  side,  whilst  the  internal  is  narrow  and  convex  in 
the  transverse  direction.  Excluding  a  narrow  vertical  zone  at  the 
inner  part  of  the  inner  division,  each  division  is  subdivided  by 
two  slight  transverse  ridges  into  three  horizontal  zones — upper, 
middle,  and  lower,  of  which  the  middle  is  the  largest  and  broadest. 
These  six  horizontal  facets  articulate  with  the  patellar  surface  of  the 
femur,  the  lower  facets  being  in  contact  with  the  upper  part  of  the 
patellar  surface  in  extension  of  the  knee-joint,  the  middle  patellar 
facets  with  the  middle  portion  of  the  patellar  surface  of  the  femur  in 
semiflexion,  and  the  upper  patellar  facets  with  the  lower  parts  of 
the  patellar  surface  of  the  femur  in  flexion  of  the  knee-joint.  The 
vertical  zone  at  the  inner  part  of  the  inner  division  of  the  articular 
surface  (close  to  the  inner  border  of  the  bone)  constitutes  a  seventh 
facet,  which  may  be  called  the  miner's  facet.  In  extreme  flexion 
of  the  knee-joint  this  facet  articulates  with  the  semilunar  facet 
(miner's  facet)  on  the  outer  part  of  the  tibial  surface  of  the  internal 
condyle  of  the  femur  close  to  the  intercondylar  fossa,  whilst  the 
upper  and  outer  horizontal  facet  is  in  contact  with  the  front  part 
of  the  external  condyle. 

The  pateUa  receives  its  arteries  from  the  superficial  branch  of 
the  anastomotica  magna  of  the  femoral,  inferior  articular  branches 
of  the  popliteal,  and  anterior  tibial  recurrent. 

Structure. — The  patella,  being  a  short  bone,  is  composed  princi- 
pally of  dense  cancellated  tissue  with  close  meshes,  surrounded 
by  compact  bone,  which  is  much  thicker  in  front  than  behind. 

Ossification.— The  original  cartilage  is  deposited  in  the  tendon  of  the  quad- 
riceps extensor  cruris  in  the  third  month  of  intra-uterine  hfe.  In  this  cartilage 
a  single  centre  appears  in  the  third  year,  and  ossification  is  completed  about 
the  age  of  puberty. 

The  Tibia. 

The  tibia,  or  shin-bone,  is  the  inner  and  larger  of  the  two 
bones  of  the  leg,  and  alone  transmits  the  weight  of  the  body  to 
the  foot.     The  posterior  surfaces  of  the  shafts  of  the   tibia  and 


THE  BONES  OF  THE  LOWER   LIMB 


225 


fibula  are  on  the  same  horizontal  plane  above  and  below,  but 
over  about  the  middle  three-fifths  the  fibula  projects  slightly 
farther  back  on  account  of  its  curve.  Anteriorly  the  tibia  is  on 
a  more  anterior  plane  than  the  fibula,  a  point  to  be  borne  in 
mind  in  making  flaps  by  transfixion.  The  tibia  is  a  long  bone, 
and  is  divisible  into  a  shaft  and  two  extremities,  upper  and 
lower. 

The  upper  extremity,  known  as  the  head,  is  broader  from  side 
to  side  than  from  before  backwards.  Antero-laterally  it  is  convex, 
but  posteriorly  it  is  rendered  concave  by  the  popliteal  notch  at  its 
centre.  The  enlargements  of  the  bone  on  either  side  of  the  head 
are  called  the  tuberosities,  external  and  internal.  The  external 
tuberosity  is  rather  smaller  than  the  internal,  and  at  its  posterior 
and  under  aspect  it  presents  a  flat  circular  facet,  directed  downwards, 


Anterior  Coriiu  of  Internal 

Fibro-Cartilac:e  Tubercle 


Anterior  Crucial  Ligament 


Anterior  Cornu  of  External 
Fibro-Cartilage 

External  Tubercle  of  Spine 


External  Condylar 
/  Surface 


Internal 
Condylar  Surface 

Internal  Tubercle  of  Spine  /'  ,'         !         \  Posterior  Cornu  of  External 

Posterior  Cornu  of  Internal  Fibro-Cartilage         ]  Popliteal  Notch  Fibro-Cartilage 

Posterior  Crucial  Ligament 

Fig.   139. — The  Head  of  the   Right   Tibia   (Superior  View). 


backwards,  and  outwards,  which  articulates  with  the  head  of  the 
fibula.  The  cartilage  of  this  facet  is  occasionally  continuous  with 
that  of  the  external  condylar  surface.  At  the  junction  of  its 
anterior  and  outer  surfaces  the  external  tuberosity  presents  an 
elevation,  which  usually  assumes  the  form  of  a  ridge,  for  the 
attachment  of  the  ilio-tibial  band  of  the  fascia  lata.  The  internal 
tuberosity  is  larger  than  the  external,  and  has  a  distinct  inclina- 
tion backwards  as  well  as  inwards,  a  point  to  be  noted  in  setting 
fractures  of  this  bone.  On  its  posterior  aspect  it  presents  a  hori- 
zontal groove  for  the  insertion  of  the  chief  portion  of  the  tendon 
of  the  semimembranosus  muscle.  On  the  anterior  aspect  of  the 
superior  extremity,  at  the  junction  of  the  head  and  shaft,  there  is  a 
well-marked  projection,  called  the  tubercle  or  anterior  tuberosity. 
It  is  fully  I  inch  in  length,  and  its  upper  border  is  about  |  inch 

15 


226  A   MANUAL  OF  ANATOMY 

below  the  level  of  the  upper  surface  of  the  head.  It  is  divisible 
into  two  nearly  equal  parts,  upper  and  lower.  The  lower  division 
is  rough,  and  is  usually  strongly  ridged  in  the  vertical  direction 
for  the  attachment  of  the  ligamentum  patellae.  The  upper  division 
is  smooth,  and  is  separated  from  that  ligament  by  a  synovial 
bursa. 

The  superior  surface  of  the  head  presents  the  two  condylar 
articular  surfaces,  separated  from  each  other  by  an  irregular  interval, 
which,  amongst  other  markings,  presents  the  bifid  tibial  spine. 
Each  surface  surmounts  the  corresponding  lateral  tuberosity. 
The  eternal  condylar  surface  is  broad  from  side  to  side,  and  is 
almost  circular.  It  is  concave  from  side  to  side,  and  concavo- 
convex  from  before  backwards.  Its  cartilage  rises  towards  the 
middle  line  to  coat  the  external  surface  of  the  outer  tubercle  of  the 
tibial  spine,  and  posteriorly  it  dips  down  for  a  little  on  the  outer 
part  of  the  back  of  the  external  tuberosity,  where  the  tendon  of 
the  popliteus  glides  over  it.  It  is  in  this  situation  where  the  carti- 
lage is  occasionally  continuous  with  that  of  the  fibular  facet.  The 
internal  condylar  surface  is  oval  and  concave,  being  elongated  from 
before  backwards,  but  narrow  from  side  to  side.  The  cartilage  of 
this  surface  rises  towards  the  middle  line  to  coat  the  internal 
surface  of  the  inner  tubercle  of  the  tibial  spine.  Each  condylar 
surface  is  deepened  by  a  semilunar  fibro-cartilage,  which  is  placed 
round  its  peripheral  part. 

The  interspace  between  the  condylar  surfaces  presents  the 
spine,  which  is  distant  from  the  posterior  border  about  one-third 
of  the  antero-posterior  measurement.  The  spine  is  formed  by  an 
upward  rising  of  the  contiguous  borders  of  the  condylar  surfaces, 
and  is  bifid,  ending  in  two  tubercles,  of  which  the  inner  is  the 
better  marked  and  longer  of  the  two.  The  interspace  between 
these  tubercles  gives  attachment  to  the  posterior  cornu  of  the 
external  semilunar  fibro-cartilage,  which  continues  to  be  attached 
to  a  depression  behind  the  outer  tubercle.  The  surfaces  of  the 
tubercles  which  face  each  other  are  free  from  cartilage,  but  the  other 
surfaces  have  each  a  cartilaginous  covering. 

In  front  of  the  spine  there  is  a  rough  depression  where  important 
structures  are  attached  as  follows  :  in  front  of  the  outer  tubercle 
of  the  spine  the  anterior  cornu  of  the  external  semilunar  fibro- 
cartilage  is  attached,  and  in  front  of  the  inner  tubercle  the  anterior 
crucial  ligament  is  attached  to  the  bone.  At  the  extreme  anterior 
and  inner  part  there  is  an  impression  for  the  anterior  cornu  of  the 
internal  semilunar  fibro-cartilage.  On  the  outer  side  of  the  im- 
pression for  the  anterior  crucial  ligament,  and  in  front  of  that  for 
the  anterior  cornu  of  the  external  semilunar  fibro-cartilage,  there 
is  a  depression  which  is  partially  occupied  by  a  small  collection 
of  fat.  At  its  outer  part,  however,  there  is  a  groove  which  receives 
a  portion  of  the  external  semilunar  fibro-cartilage  in  extension  of 
the  knee-joint.  The  immediately  adjacent  portion  of  the  external 
condylar  surface  is  specially  facetted  for  the  play  of  part  of  the 


THE  BONES  OF  THE  LOWER  LIMB  227 

external  condyle  of  the  femur  in  extension  of  the  joint.  Behind  the 
tibial  spine  there  is  a  more  limited  rough  depression,  which  leads 
backwards  to  the  popliteal  notch.  The  posterior  cornu  of  the 
internal  semilunar  fibro-cartilage  is  attached  to  the  inner  part  of 
this  depression,  and  the  posterior  crucial  ligament  is  attached  to 
its  back  part,  as  well  as  to  the  popliteal  notch. 

Order  of  Structures  attached  to  the  Head. — The  structures, 
enumerated  as  nearly  as  possible  in  order  from  before  backwards, 
are  as  follows  : 

1.  Anterior  cornu  of  internal  semilunar  fibro-cartilage. 

2.  Anterior  crucial  ligament. 

3.  Anterior  cornu  of  external  semilunar  fibro-cartilage. 

4.  Posterior  cornu  of  external  semilunar  fibro-cartilage. 

5.  Posterior  cornu  of  internal  semilunar  fibro-cartilage. 

6.  Posterior  crucial  ligament. 

The  head  is  pierced  all  round  by  many  nutrient  foramina 
for  branches  of  the  inferior  articular  arteries  of  the  popliteal, 
and  of  the  posterior  and  anterior  tibial  recurrents  of  the  anterior 
tibial. 

The  shaft  is  massive  and  triangular.  It  diminishes  in  size  from 
above  downwards  over  its  upper  two-thirds,  and  then  gradually 
enlarges  towards  its  lower  end.  It  presents  three  borders  and  three 
surfaces.  The  anterior  border  extends  from  the  outer  side  of  the 
anterior  tuberosity  above  to  the  anterior  margin  of  the  internal 
malleolus  below.  Over  the  upper  two-thirds,  where  it  occupies 
the  middle  line,  it  is  prominent,  and  is  known  as  the  crest  or  shin- 
ridge.  This  is  doubly  curved,  the  convexity  of  the  upper  curve 
being  directed  inwards,  and  that  of  the  lower  outwards.  Over  the 
lower  third  the  anterior  border  inclines  inwards,  and  the  external 
surface  of  the  shaft  is  thus  allowed  to  come  forwards.  The  crest 
is  subcutaneous,  and  gives  attachment  to  the  deep  fascia  of  the  leg. 
The  internal  border  extends  from  the  inner  and  back  part  of 
the  internal  tuberosity  to  the  posterior  margin  of  the  internal 
malleolus.  For  3  or  4  inches  superiorly  it  is  rough,  and  gives 
attachment  to  the  internal  lateral  ligament  of  the  knee-joint.  Over 
its  middle  third  it  is  prominent,  and  it  here  gives  origin  to  a  portion 
of  the  soleus  as  low  as  the  centre  of  the  bone.  The  external  or  inter- 
osseous border  extends  from  the  front  of  the  fibular  facet  above 
to  a  point  about  2  inches  from  the  lower  end,  where  it  bifurcates. 
The  two  divisions  pass  to  the  front  and  back  of  the  sigmoid  cavity, 
and  enclose  between  them  a  rough  triangular  surface  for  the 
inferior  interosseous  ligament.  This  border  is  sharp  and  wiry,  and 
gives  attachment  to  the  interosseous  membrane. 

The  internal  surface  is  situated  between  the  crest  and  internal 
border.  It  is  for  the  most  part  subcutaneous,  and  slightly 
convex.  Superiorly,  where  it  becomes  expanded  and  flattened,  it 
presents  a  vertical  rough  area,  Ijehind  the  tubercle,  for  the  insertion 
of  the  sartorius,  and  behind  this  two  vertical  rough  impressions  in 
the  same  line  with  each  otlier,  the  u[)per  of  which  gives  insertion 

15—2 


A  maMual  of  anatomy 

Tibial  Spine 

A 


External  Tuberosity  of  Tibia 

Biceps  Femoris  — ^t 
Head  of  Fibula_ 


Peroneus  Longus J 

Extensor  Longus  Digitorum . 

Extensor  Proprius  Hallucis 

Antero-external  Border ! 

Postero-external  Border  ._ 

Peroneus  Brevis J 


,.„,|i|ji. 


I Internal  Tuberosity  of  Tibia 

-Tubercle 

_M- Gracilis 

Sartorius 

Semitendinosus 


Peroneus  Tertius 


External  Surface  and 

Tibialis  Anticiis 

Anterior  Border  or  Crest 


.  Internal  Border 


Triangular  Subcutaneous 
Surface 


External  Malleolus^-. 

Internal  Malleolus 

Fig.  140. — The  Right  Tibia  and  Fibula  (Anterior  View), 


THE  BONES  OF  THE  LOWER  LIMB  229 

to  the  gracilis,  and  the  lower  to  the  semitendinosus.  The  external 
surface  is  situated  between  the  crest  and  interosseous  border.  It 
is  concave  over  its  upper  two-thirds,  where  it  gives  origin  to  the 
tibialis  anticus.  Over  the  lower  third,  where  it  is  convex,  it  turns 
to  the  front  and  su])ports  the  extensor  tendons,  and  anterior  tibial 
vessels  and  nerve.  The  posterior  surface  lies  between  the  inter- 
osseous and  internal  borders.  Superiorly  it  is  crossed  by  the 
popliteal  or  oblique  line,  which  is  rough,  and  extends  from  the 
fibular  facet  downwards  and  inwards  to  the  internal  border  at 
about  the  junction  of  the  upper  third  and  lower  two-thirds.  This 
line  gives  attachment  to  the  popliteal  fascia  and  part  of  the  soleus, 
whilst  the  triangular  popliteal  surface  above  gives  insertion  to 
the  popliteus  muscle.  The  posterior  surface  below  the  oblique 
line  presents  over  its  middle  third  a  vertical  ridge  which  divides 
it  into  two  parts.  The  outer  portion  is  narrow,  and  gives  origin 
to  the  tibialis  posticus  as  low  as  a  point  just  below  the  centre  of 
the  bone.  The  inner  portion  is  broad,  and  gives  origin  to  the 
flexor  longus  digitorum  over  the  middle  two-fourths  of  the  bone. 
A  little  below  the  oblique  line,  close  to  the  outer  side  of  the  vertical 
ridge,  is  the  medullary  foramen  for  a  large  branch  of  the  posterior 
tibial  artery.  This  foramen,  which  is  the  largest  of  its  class,  and 
the  canal  to  which  it  leads  are  directed  downwards.  The  posterior 
surface  in  its  lower  third  supports  the  flexor  tendons,  and  posterior 
tibial  vessels  and  nerve. 

The  lower  extremity  presents  a  quadrilateral  articular  surface, 
concave  from  before  backwards,  and  wider  in  this  direction  exter- 
nally than  internally.  It  is  broader  in  front  than  behind,  and 
articulates  with  the  superior  surface  of  the  astragalus.  The  pos- 
terior border  projects  somewhat  lower  than  the  anterior.  The 
anterior  surface,  immediately  above  the  anterior  border,  is  depressed 
and  rough  for  the  anterior  ligament  of  the  ankle-joint.  The 
posterior  border  gives  attachment  to  the  posterior  ligament  of 
the  ankle-joint  as  far  inwards  as  the  groove  behind  the  internal 
malleolus.  It  presents  the  following  grooves  :  one  for  the  tendon 
of  the  flexor  longus  hallucis  near  the  outer  end  ;  one  (very  faint) 
near  the  centre  for  the  posterior  tibial  vessels  and  nerve ;  and  one 
mainly  situated  on  the  back  of  the  internal  malleolus  for  the  tendons 
of  the  tibialis  posticus  and  flexor  longus  digitorum. 

The  inner  aspect  of  the  lower  extremity  presents  the  internal 
malleolus,  which  is  a  strong  process  having  a  downward  direction.  Its 
internal  surface  is  rough,  convex,  and  subcutaneous.  The  external 
surface  is  covered  by  cartilage,  continuous  with  that  which  coats 
the  lower  extremity.  The  j)lane  of  this  surface  is  vertical,  and  the 
cartilage  coats  it  more  deeply  in  front  than  behind.  It  articulates 
with  the  internal  surface  of  the  astragalus.  The  anterior  border 
is  rough  and  round  for  the  attachment  of  the  anterior  and  internal 
lateral  ligaments  of  the  ankle-joint.  The  lower  border  is  indented 
by  a  notch,  in  front  of  which  is  the  projection  known  as  the  tip, 
the  internal  lateral  ligament  being  attached  to  both  of  these  parts. 


'^JU 


Tibial  Spine 
Semimembrano-^u';  /    \       Popliteal  Nolcb 


..Styloid  Process  of  Fibula 


Internal  Tuberositj'  of  Tibia  — 


Popliteal  Surface  and 

Popliteus 


Soleus 
Oblique  Line- 


Tibialis  Posticus 

Medullary  Foramen 

Internal  Border 

Fle.xor  Tongus  Digitorum 


Soleus 


Posterior  Surface 


,  Postero  external  Border 


I Fle.xor  Lonarus  Hallucis 


Medullary  Foramen 


-Peroaeus  Brevis 
-Postero-e.xternal  Border 

-Antero-e.xternal  Border 


Tip  of  Internal  Malleolus,' 

Groove  for  Tibialis  Posticus  and         ;  \l,^X 

Fle.xor  Longus  Digitorum  ■  7*'      Peroneal  Groove 

'  Tip  of  External  Malleolus 

Groove  for  Flexor 
Longus  Hallucis 


Fig,    141. — The  Right  Tibia  and  Fibula  (Posterior  View). 


THE  BONES  OF  THE  LOWER  LIMB 


231 


Posteriorly  is  the  groove  for  the  tendons  of  the  tibiahs  posticus  and 
flexor  longus  digitorum.  The  outer  aspect  of  the  lower  extremity 
presents  a  concave  facet  for  the  fibula,  and  above  this  a  concave 
triangular  rough  surface  about  i|  inches  long  for  the  inferior  inter- 
osseous ligament. 

The  inferior  extremity  of  the  tibia  presents  many  nutrient 
foramina  for  branches  of  the  anterior  and  posterior  tibial,  internal 
malleolar,  and  anterior  peroneal,  arteries. 

Articulations. — Superiorly  with  the  condyles  of  the  femur  above, 
and  the  head  of  the  fibula  postero-externally,  and  inferiorly  with 
the  fibula  externally,  and  the  superior  and  internal  aspects  of 
the  astragalus  below. 

Structure. — The  structure  is  that  of  a  long  bone.  The  medullary 
canal  extends  above  to  a  point  about  i\  inches  below  the  lower 
margin  of  the  anterior  tuberosity,  and  inferiorly  to  a  point  about 
I  inch  below  the  lower  extremity  of  the  crest.  The  cancellated 
tissue  of  the  upper  epiphysis  has  its  lamellae  disposed  somewhat 
vertically,  whilst  that  of  the  upper  end  of  the  shaft  has  its  lamells 
arranged  in  the  form  of  arches.  In  the  lower  part  of  the  shaft  the 
cancellous  lamellae  are  disposed  vertically,  and  the  cancellated 
tissue  of  the  lower  epiphysis  is  closely  meshed. 

Varieties. — (i)  The  tibia  is  sometimes  much  compressed  laterally,  which  leads 
to  an  increase  in  its  antero-posterior  diameter.  In  these  cases  the  vertical 
ridge  posteriorly  becomes  unduly  promi- 
nent, a  condition  which  is  associated 
with  a  large  development  of  the  tibialis 
posticus  muscle.  Such  a  bone  is  spoken  of 
as  being  platycnonic  (broad -legged),  and 
the  condition  is  known  as  platycnemism 
(broadness  of  tibia).  (2)  The  anterior 
aspect  of  the  lower  extremity  of  the  bone 
sometimes  presents  a  pressure  facet  at  its 
outer  part  for  articulation  with  the  upper 
surface  of  the  neck  of  the  astragalus  in 
extreme  flexion  of  the  ankle-joint. 

Ossification. — -The  tibia  is  ossified  in 
cartilage  from  i  primary  and  3  secondary 
centres. 

The  primary  centre  appears  at  the 
centre  of  the  shaft  about  the  jth  week. 
The  3  secondary  centres  are  disposed  as 
follows:  2  are  siipcrinr.  one  for  the  head, 
and  the  other  for  the  tubercle  ;  and  i  is 
inferior  for  the  lower  extremity  and  inter- 
nal malleolus.  Upper  Extremity. — -The 
centre  lor  the  head  appears  just  before 
birth,  and  from  it  the  external  and  in- 
ternal tuberosities  are  ossified,  which  constitute  the  superior  epiphysis.  The 
centre  lor  the  tubercle  appears  about  the  12th  year.  Soon  afterwards  it  joins 
th<-  superior  epiphysis,  which  unites  with  the  shaft  about  the  22nd  year.  In 
some  cases  the  tubercle  is  entirely  ossified  from  the  centre  for  the  head.  In 
other  cases  thj  upper  smooth  part  of  the  tubercle  is  ossified  from  the  centre 
for  the  head,  and  the  lower  rouf'Ii  part  derives  its  ossification  from  the  primary 
centre  for  the  shaft.  Lower  Extremity. — The  centre  for  the  lower  ex- 
tremity and  internal  malleolus  .ipivars  towards  the  end  of  the  2nd  year,  and 
this  lower  epiphysis  joins  al)out  the  \Sth  year. 


Appears  just  before  birth,  and 
joins  about  22 

May  appear  about  the  12th  year, 
and  joins  soon  thereafter 


-Appears  in  the  7th  week 
(intra-uterine) 


Fig. 


Appears  at  end  of  ist  year, 
and  joins  about  18 

— Ossification  of  thk 
Tibia. 


232  A  MANUAL  OF  ANATOMY 


The  Fibula, 


The  fibula,  or  peroneal  bone,  is  situated  on  the  outer  side  of  the 
tibia.  It  is  very  slender  for  its  length,  and  is  a  rudimentary  bone. 
It  takes  no  part  in  transmitting  the  weight  of  the  body,  but  serves 
chiefly  to  afford  attachment  to  muscles,  though  it  also  forms  part 
^i  the  ankle-joint,  and  acts  as  a  brace  or  support  to  the  tibia.  It 
is  a  long  bone,  and  is  divisible  into  a  shaft  and  two  extremities, 
upper  and  lower. 

The  upper  extremity,  or  head,  is  enlarged  and  knob-like,  its  upper 
surface  being  somewhat  flattened  and  sloping.  It  is  situated  about 
f  inch  below  the  level  of  the  head  of  the  tibia.  Posteriorly  it  is 
prolonged  upwards  into  the  styloid  process,  to  the  tip  of  which  the 
sJwrt  external  lateral  ligament  of  the  knee-joint  is  attached.  In  front 
of  this  process  the  upper  surface  of  the  head  is  sloped  downwards 
and  forwards,  and  is  divisible  into  an  articular  and  a  non-articular 
part.  The  articular  division  is  internal  in  position,  and  takes  the 
form  of  a  flat  circular  facet,  which  is  directed  upwards,  inwards,  and 
forwards,  to  articulate  with  the  facet  on  the  posterior  and  under 
aspect  of  the  external  tuberosity  of  the  tibia,  by  which  latter  it 
is  overhung.  The  non-articular  division  is  external  in  position,  and 
takes  the  form  of  a  rough  depression,  into  which  the  tendon  of  the 
biceps  femoris,  previously  divided  into  two  parts  by  the  long 
external  lateral  ligament,  takes  insertion.  Posteriorly  the  head 
gives  origin  to  the  soleus.  Externally  it  gives  origin  to  the  peroneus 
longus,  and  at  a  point  nearlj'  ^  an  inch  anterior  to  the  styloid 
process  its  outer  margin  gives  attachment  to  the  long  external 
lateral  ligament.  Anteriorly  it  gives  origin  to  the  extensor  longus 
digitorum.  The  constricted  part  below  the  head  is  called  the 
■neck. 

The  upper  extremity  presents  several  nutrient  foramina  for 
branches  of  the  inferior  external  articular  of  the  popliteal,  and 
superior  fibular  of  the  anterior  tibial,  arteries. 

The  lower  extremity  is  prolonged  downwards  into  a  massive  pro- 
jection, called  the  external  malleolus,  which  is  not  only  larger,  but 
lower  down  and  farther  back,  than  the  internal  malleolus.  It 
is  triangular  or  p3rramidal,  the  base  being  directed  upwards. 
The  external  surface  is  rough,  convex,  and  subcutaneous.  The 
internal  surface  is  divisible  into  two  parts,  articular  and  non- 
articular.  The  articular  division  is  anterior  in  position,  and  occupies 
about  two-thirds  of  the  surface.  It  is  triangular  and  convex,  and 
it  mainly  articulates  with  the  outer  surface  of  the  astragalus. 
Superiorly,  however,  for  about  J  inch,  it  assumes  a  some- 
what semilunar  outline,  and  this  portion  articulates  with  the 
outer  aspect  of  the  tibia.  The  non-articular  division  is  posterior 
in  position,  and  occupies  about  one-third  of  the  surface,  xu  is 
rough,  depressed,  and  triangular,  and  is  known  as  the  digital  fossa. 
Superiorl}/  it  gives  attachment  to  the  transverse  ligament  of  the 
inferior  tibio-fibular  joint,  and  interiorly  to  the  posterior  fasciculus 


THE  BONES  OF  THE  LOWER  LIMB 


233 


of  the  external  lateral  ligament 
of  the  ankle-joint.  Above  t?ie 
external  malleolus  on  the  inner 
aspect  there  is  a  rough,  convex, 
triangular  surface  about  i^  inches 
long  for  the  inferior  interosseous 
ligament.  The  anterior  border 
projects  at  first  forwards,  and 
then  slopes  downwards  and  back- 
wards to  the  tip.  The  jjrojecting 
part  gives  attachment  to  the 
anterior  ligament,  and  the  lower 
portion  of  the  sloping  i:)art  to  the 
anterior  fasciculus  of  the  external 
lateral  ligament  of  the  ankle- 
joint.  The  posterior  border  is 
shorter  than  the  anterior,  and  is 
vertical.  It  presents  the  peroneal 
groove  for  the  tendons  of  the 
peroneus  longus  and  peroneus 
brevis.  The  tip  is  the  most 
dependent  part,  and  is  situated  at 
the  meetingof  the  posterior  border 
and  the  lower  sloping  part  of 
the  anterior  border.  It  gives  at- 
tachment to  the  middle  fasciculus 
of  the  external  lateral  ligament. 

The  lower  extremity  presents 
several  nutrient  foramina  for 
branches  of  the  anterior  and 
posterior  peroneal,  and  external 
malleolar,  arteries. 

The  shaft  is  slightly  curved, 
the  convexity  being  directed 
backwards  in  the  upper  part, 
and  inwards  lower  down.  It 
is  quadrilateral  in  its  upper 
three-fourths,  where  it  presents 
four  borders  anrl  four  surfaces, 
but  it  is  somewhat  triangular 
in  the  lower  fourth.  The  anlcro- 
external  horder,  which  is  the 
most  prominent,  commences  in 
front  of  the  head,  and  passes 
straight  downwards  until  it 
reaches  the  loVver  fifth,  where  it 
bifurcates.  One  division  passes 
to  the  anterior  margin  of  the  ex- 
ternal malleolus,  and  \.]\<t  other  to 


-Styloid  Process 

-  Tiljial  Facet  on  Head 


1— -  Tibialis  Posticus 


r Medullary  Foramen 


_  I'ostero-iiitcrnal  liorder 
Antero-internal  or  Interosseous 
Border 


Antero-external  Horder 
—  I'listero-external  Border 


I 'I'riangular  Area  for  Inferior 

Interosseous  Lii^anient 


.  Facet  on  External  Malleolus 
for  Astragalus 

■  Oigital  Fossa 

Fig.   143. — Thr  Right  Fibula 
(Intkknal  Viiiw). 


234  A   MANUAL  OF  ANATOMY 

the  posterior  margin,  external  to  the  peroneal  groove.  These  two 
divisions  enclose  between  them  a  triangular  area  which  is  continuous 
with  the  outer  surface  of  the  external  malleolus.  This  border  gives 
attachment  to  the  antero-external  intermuscular  septum.  The 
antero -internal  or  interosseous  border,  which  gives  attachment  to 
the  interosseous  membrane,  also  commences  in  front  of  the  head, 
where  it  is  very  near  to  the  antero-external  border.  As  it  descends 
it  keeps  near  to  that  border  at  first,  but  beyond  the  upper  third  it 
gradually  diverges  from  it,  and  on  reaching  a  point  about  2  inches 
above  the  external  malleolus  it  bifurcates.  One  division  passes  to 
the  anterior  margin  of  the  malleolus,  becoming  incorporated  with 
one  of  the  divisions  of  the  antero-external  border,  whilst  the  other 
passes  to  the  posterior  margin  of  the  malleolus,  internal  to  the 
upper  end  of  the  peroneal  groove.  The  two  divisions,  as  they 
diverge,  enclose  a  rough  triangular  area,  which  is  slightly  convex 
and  gives  attachment  to  the  inferior  interosseous  ligament.  The 
postero-internal  harder  commences  on  the  inner  side  of  the  head, 
not  far  from  the  antero-internal.  It  descends  in  a  backwardly- 
curved  manner,  gradually  leaving  the  antero-internal  border,  but 
subsequently  approaching  it,  until  on  reaching  the  junction  of  the 
upper  two- thirds  and  lower  third  it  ends  by  joining  it.  This  border 
gives  attachment  to  an  intermuscular  septum,  which  separates 
the  tibialis  posticus  from  the  soleus  and  flexor  longus  hallucis. 
The  postero-external  border  extends  from  the  back  of  the  head  to  the 
back  of  the  external  malleolus,  internal  to  the  peroneal  groove,  and 
in  its  lower  part  it  turns  inwards.  It  gives  attachment  to  the 
postero-external  intermuscular  septum. 

The  anterior  surface  is  situated  between  the  antero-external  and 
antero-internal  or  interosseous  borders.  It  is  very  narrow  over 
about  its  upper  half,  but  becomes  wider  below.  It  gives  origin  over 
about  its  upper  three-fourths  to  the  extensor  longus  digitorum, 
over  its  lower  fourth  (except  about  i  inch  below)  to  the  peroneus 
tertius,  and  over  about  its  middle  two-fourths  to  the  extensor 
proprius  hallucis,  which  is  nearest  to  the  antero-internal  border. 
The  internal  surface  is  situated  between  the  aniero-internal  and 
postero-internal  borders.  It  is  concave  and  fusiform,  being  narrow 
above  and  below,  but  wide  at  the  centre,  and  it  gives  origin  to  the 
tibialis  posticus.  The  posterior  s^irface  is  limited  by  the  postero- 
internal and  postero-external  borders,  and  in  its  lower  fourth  it 
undergoes  a  twist,  and  turns  round  to  become  internal.  Over  its 
upper  third  it  gives  origin  to  a  part  of  the  soleus,  and  over  its  lower 
two-thirds,  except  the  last  inch  or  more,  to  the  flexor  longus  hallucis. 
The  external  surface  lies  between  the  antero-external  and  postero- 
external borders.  It  is  the  broadest,  and  in  muscular  subjects  is 
deeply  grooved  over  rather  more  than  its  upper  half.  Inferiorly  it 
undergoes  a  twist,  and  turns  round  to  become  posterior,  where 
it  leads  directly  to  the  peroneal  groove  on  the  back  of  the  external 
malleolus.  In  this  manner  the  two  peroneal  tendons  are  guided  to 
this  groove.      The  upper  two-thirds  of  this  surface  give  origin  to 


THE  BONES  OF  THE  LOWER  LIMB 


235 


the  peroneus  longus,  and  the  lower  two-thirds,  except  the  last 
2  inches,  to  the  peroneus  brevis,  these  two  muscles  overlapping 
towards  the  centre  of  the  bone. 

The  medullary  foramen,  which  is  small,  is  usually  situated  on  the 
posterior  surtace,  but  may  be  on  the  internal,  a  little  above  the 
centre,  and  there  may  be  an  additional  one  a  little  higher  up.  It  is 
for  a  branch  of  the  peroneal  artery,  and  the  direction  of  the  foramen 
and  the  canal  to  w^hich  it  leads  is  downwards  towards  the  ankle. 

Articulations. — Superiorly  with  the  external  tuberosity  of  the 
tibia,  and  inferiorly  with  the  outer  aspect  of  the  tibia,  and  the  ex- 
ternal surface  of  the  astragalus. 

Structure. — The  structure  is  that  of  a  long  bone,  and  the  marrow 
canal  is  limited  to  about  the  middle  three-fifths  of  the  shaft. 

Ossification. — The  fibula  ossifies  in  cartilage  from  one  primary,  and  two 
secondary,  centres.  The  primary  centre  for  the  shaft  appears  in  the  eighth 
week  of  intra-uterine  life.  At  birth  the  shaft 
is  ossified,  but  the  extremities  are  cartilaginous. 
The  centre  for  the  lower  extremity  appears  in 
the  second  year,  and  that  for  the  upper  extremity 
about  the  fourth  year.  The  lower  epiphysis 
joins  the  shaft  about  twenty,  and  the  upper 
about  twenty-three.  The  fibula  forms  an  excep- 
tion to  the  general  law  of  ossification  appUcable 
to  long  bones  with  an  epiphysis,  or  epiphyses,  at 
either  end,  which  may  be  here  restated  as 
follows:  '  The  epiphysis  or  epiphyses,  at  the  end 
towards  which  the  medullary  foramen  and  the 
canal  to  which  it  leads  arc  directed,  are  the  last  to 
show  signs  of  ossification,  but  they  are  the  first  to 
join  the  shaft.'  In  the  fibula  the  lower  epiphysis 
not  only  joins  the  shaft  first,  but  it  is  the  first  to 
show  signs  of  ossification — due  to  the  fact  that 
this  extremity  is  the  least  rudimentary  part 
of  the  bone. 

The  fibula  in  early  life  articulates  with 
the  femur.  At  about  the  seventh  month 
of  intra-uterine  life  the  tibial  and  fibular 
malleoli  are  of  nearly  equal  proportions,  but  by 
the  second  year,  previous  to  the  appearance 
of  its  centre  of  ossification,  the  fibular  malleolus  has  attained  the  large 
relative  size  which  characterizes  it  throughout  life. 


Appears  about  the  4th  Year, 
and  joins  about  23 


Appears  in  the  8th  Week 
(intra-uterine) 


Fig. 


.^.ppears  in  the  2nd  Year, 
and  joins  about  20 

144. — Ossification  of 

THE    FlBUL.\. 


The  Tarsus. 

The  tarsus  is  composed  of  seven  short  bones,  namely,  the 
astragalus,  os  calcis,  navicular  or  scaphoid,  three  cuneiforms,  and 
cuboid. 

The  first  two  constitute  the  proximal  row,  the  astragalus  lying 
above  the  os  calcis,  and  the  last  four  comprise  the  distal  row,  the 
order  from  the  inner  or  tibial  to  the  outer  or  fibular  side  being  in- 
ternal, middle,  and  external  cuneiform  bones,  and  cuboid.  Th:^ 
navicular  occupies  an  intermediat-'  jjosition. 


236  A   MANUAL  OF  ANATOMY 

The  Astragalus. 

The  astragalus^  or  talus,  is  characterized  by  having  a  head,  neck, 
and  body.  It  is  situated  between  the  tibia  above  and  the  os 
calcis  below,  is  grasped  laterally  by  the  tibial  and  fibular  malleoli, 
and  has  the  navicular  in  front.  It  is  the  only  tarsal  bone  which 
receives  directly  the  weight  of  the  body,  and  it  lies  with  its  long 
axis  directed  forwards  and  inwards.  In  point  of  size  it  comes 
next  to  the  os  calcis. 

The  head  forms  the  anterior  part  of  the  bone,  and  presents  an 
extensive  convex  articular  surface,  which  looks  forwards  and  also 
downwards.  It  is  divided  into  three  facets,  called  navicular, 
sustentacular,  and  '  spring.'  The  navicular  facet,  which  is  placed 
on  the  anterior  surface,  is  pyriform,  and  its  long  axis  is  directed 
downwards  and  inwards.  The  sustentacular  facet,  continuous  with 
the  foregoing,  is  situated  on  the  inferior  surface.  It  is  convex  and 
elliptical,  and  its  long  axis  is  directed  forwards  and  outwards.  It 
is  often  crossed  by  an  elevated  ridge  a  little  anterior  to  the  centre, 
and  it  articulates  with  the  sustentacular  facet  on  the  upper  surface 
of  the  OS  calcis.  The  spring  facet  is  situated  on  the  inner  aspect 
of  the  inferior  surface,  and  is  in  contact  with  the  superior  surface  of 
the  inferior  calcaneo-navicular  or  'spring  '  ligament. 

The  neck  is  the  constricted  part  behind  the  head.  It  is  con- 
spicuous superiorly,  and  passes  inferiorly  into  the  interosseous 
groove.  This  groove  is  directed  forwards  and  outwards,  its  inner 
part  being  narrow  and  deep,  and  the  outer  wide  and  shallow.  It 
gives  attachment  to  the  strong  interosseous  ligament  which  binds 
the  astragalus  to  the  os  calcis.  The  neck  is  perforated  all  round 
with  numerous  nutrient  foramina  for  offsets  of  the  dorsalis  pedis 
artery  and  its  tarsal  branch. 

The  body  is  quadrilateral,  and  presents  four  surfaces  and  a  pos- 
terior border.  The  superior  surface  presents  an  extensive  trochlear 
facet,  which  is  concave  from  side  to  side,  and  convex  from  before 
backwards.  Posteriorly  it  slopes  downwards,  and  in  this  situation 
it  usually  presents  a  transverse  groove  for  the  play  of  the  transverse 
ligament.  The  inner  border  is  straight  and  slightly  depressed, 
and  as  a  rule  it  extends  rather  farther  back  than  the  outer, 
which  latter  is  somewhat  sinuous.  The  surface  is  broader  in 
front  than  behind.  The  external  surface  is  deep,  and  presents  a 
large  triangular  facet  for  the  external  malleolus,  the  apex  being 
downwards.  It  is  concave  from  above  downwards,  and,  immediately 
in  front  of  it,  the  anterior  fasciculus  of  the  external  lateral  ligament 
of  the  ankle-joint  takes  attachment.  The  internal  surface  pre- 
sents superiorly  a  falciform  facet,  broad  in  front  and  pointed 
behind,  for  the  internal  malleolus.  This  facet  in  the  foetus  en- 
croaches on  the  inner  side  of  the  neck,  a  condition  which  is  associ- 
ated with  the  inversion  of  the  foot  at  that  period  of  life.  This 
sometimes  occurs  in  the  adult,  and,  if  it  does  so  to  any  marked 
extent,  it  usually  accompanies  the  condition  known  as  talipes  varus. 


THE  BONES  OF  THE  LOWER  LIMB 


237 


The  inferior  surface  presents  a  large  oval  facet,  concave  from  within 
forwards  and  outwards,  for  articulation  with  the  os  calcis.  The 
posterior  border  is  short,  stout,  and  oblique,  its  direction  being 
inwards  and  forwards.    It  presents  a  groove,  which  is  directed  down- 


Head 


For  Internal  Malleolus  __ 


For  Tibia  -' 


Internal  Tubercle 


Groove  for 
Flexor  Longus  Hallucis 


For  External  Malleolus 


External  Tubercle 


Navicular  Facet 


Facet  for  Spring  Ligament 


For  Os  Calcis  ■^~ 
Interosseous  Groove  — 

For  0>  Calcis    _  . 


Fig.    145. — The    Right    Astragalus. 
A,  Superior  View  ;   B,  Inferior  View. 

wards  and  inwards,  for  the  tendon  of  the  flexor  longus  hallucis. 
On  either  side  of  this  groove  there  is  a  tubercle,  the  internal  being 
rudimentary,  whilst  the  external  is  well  developed  and  gives  attach- 
ment superiorly  to  the  j)osterior  fasciculus  of  the  external  lateral 
ligament  of  the  ankle-joint. 


238  A  MANUAL  OF  ANATOMY 

The  astragalus  derives  its  blood-supply  from  branches  of  the 
dorsalis  pedis  artery. 

Articulations. — Superiorly  with  the  shaft,  and  internally  with  the 
internal  malleolus,  of  the  tibia  ;  externally  with  the  external  malle- 
olus of  the  fibula  ;  inferiorly  with  the  os  calcis ;  and  anteriorly  with 
the  navicular,  and  occasionally  with  the  lower  and  inner  angle  of 
the  cuboid. 

Structure. — The  astragalus,  being  a  short  bone,  is  composed  of 
cancellated  tissue,  surrounded  by  a  thin  shell  of  compact  bone. 
The  lamella  of  the  cancellated  tissue  are  arranged  in  a  curved 
manner,  and  in  two  sets.  Some  pass  downwards  and  backwards 
from  the  superior  surface  to  the  posterior  calcaneal  facet,  whilst 
others  arch  downwards  and  forwards  from  the  superior  surface  to 
the  neck,  these  being  the  directions  in  which  weight  is  transmitted. 

Varieties. — (i)  The  external  tubercle  on  the  posterior  border  may  form  a 
separate  ossicle,  called  the  os  trigonum.  (2)  There  may  be  a  pressure  facet  on 
the  upper  surface  of  the  neck  at  its  outer  part,  due  to  prolonged  contact  with 
the  anterior  margin  of  the  lower  end  of  the  tiJDia. 


The  Cs  Calcis. 

The  OS  calcis,  or  calcaneum,  is  the  largest  bone  of  the  tarsus,  and 
is  characterized  by  its  elongation,  lateral  compression,  and  en- 
largement posteriorly  into  a  tuberosity.  It  is  situated  below  the 
astragalus,  and  behind  the  cuboid,  where  it  lies  with  its  long  axis 
directed  forwards  and  outwards.  It  presents  two  extremities  and 
four  surfaces. 

The  posterior  extremity,  which  is  enlarged,  forms  the  tuberosity 
or  tuber  calcis,  and  constitutes  the  prominence  of  the  heel. 
Posteriorly  it  is  divided  into  three  zones — an  upper,  which  is 
smooth  and  separated  from  the  tendo  Achillis  by  a  bursa  ;  a 
middle,  rough  and  vertically  ridged,  for  the  insertion  of  the  tendo 
Achillis  ;  and  a  lower,  which  is  continuous  with  the  tubercles  on 
the  plantar  aspect,  and  supports  the  fat  of  the  heel.  In  front  of 
the  tuber  calcis  there  is  a  constriction,  called  the  neck. 

The  anterior  extremity  presents  a  large,  somewhat  triangular 
facet,  narrow  towards  the  sole,  which  is  concave  from  above  down- 
wards and  outwards,  and  convex  from  side  to  side,  for  articulation 
with  the  cuboid. 

The  superior  surface  presents  over  its  anterior  part  two  facets  for 
the  astragalus,  separated  by  an  oblique  groove,  and  posteriorly  a 
non-articular  surface.  The  antero-internal  or  sustentacular  facet 
surmounts  the  sustentaculum  tali.  It  is  concave  and  somewhat 
elliptical,  its  long  axis  being  directed  forwards  and  outwards.  It 
is  constricted  in  front  of  the  centre,  and  is  sometimes  broken 
up  into  two  facets  by  a  rough  groove  The  postero-external  facet 
is  large,  oval,  and  convex  from  behind  forwards  and  outwards. 
The  intervening  groove,  which  is  directed  forwards  and  outwards, 
becomes  wide  and  shallow  externally,  and  in  front  of  the  outer 


THE  BONES  OF  THE  LOWER  LIMB 


239 


part  of  the  groove  the  upper  surface  gives  origin  to  a  portion  of  the 
extensor  brevis  digitorum,  and  the  fundiform  ligament  of  Retzius. 
When  the  astragalus  is  in  position  this  groove  is  converted  into  a 
short  tunnel,  called  the  sinus  pedis,  which  is  occupied  by  the  inter- 
osseous ligament.  The  superior  surface  behind  the  articular  portion 
is  rough,  and  supports  a  collection  of  fat. 


For  Astra^alu'i 


Interosseous  Groove 


--Peroneal  Spine 


For  Astragalus 


Tubercle  for  Middle  Fasciculus 
of  External  Lateral  Ligament 


For  Astragalus 


For  Bursa 


For  Tendo 
Achillis 


For  Cuboid ' 

i 
Anterior  Tubercle 


Interna 
Internal  Surface 


Sustentaculum  Tali, 
with  Oroove  below  it  for 
Flexor  Longus  Hallucis 


Fig.   146.— The  Right  Os  Calcis. 
A,    Superior    View ;    B,    Internal    View. 

The  inferior  surface  is  narrow  and  rough.  Posteriorly  it  presents 
two  tubercles,  the  outer  of  which  is  small  but  promment,  whilst 
the  inner  is  large  and  blunt.  The  outer  tubercle  gives  attach- 
ment to  the  external  division  of  the  plantar  fascia,  and  a 
portion  of  the  abductor  minimi  digiti,  whilst  the  inner  gives  attach- 
ment to  the  central  and  internal  divisions  of  the  plantar  fascia, 


240  A  MANUAL  OF  ANATOMY 

the  outer  head  of  the  abductor  hallucis,  the  flexor  brevis  digitorum, 
and  a  portion  of  the  abductor  minimi  digiti.  The  greater  part  of 
the  inferior  surface  gives  attachment  to  the  long  plantar  ligament, 
and  anteriorly  it  presents  a  small  round  eminence,  called  the  anterior 
tubercle,  to  which  the  short  plantar  ligament  is  attached. 

The  internal  surface  is  concave,  and  is  overhung  at  its  antero- 
superior  part  by  the  sustentaculum  tali.  This  latter  is  concave 
and  articular  above  for  the  astragalus,  and  below  it  presents  a  groove 
for  the  flexor  longus  hallucis.  Anteriorly  it  gives  attachment  to  the 
inferior  calcaneo-navicular  or  '  spring  '  ligament,  below  which  a  slip 
of  the  tibialis  posticus  takes  insertion,  and  its  inner  margin  gives 
attachment  to  fibres  of  the  internal  lateral  ligament  of  the  ankle- 
joint.  The  general  concavity  ot  the  internal  surface  supports  the 
tendon  of  the  flexor  longus  digitorum  and  the  plantar  vessels  and 
nerves,  and  anteriorly  it  affords  origin  to  the  inner  head  of  the 
flexor  accessorius. 

The  external  surface  is  for  the  most  part  flat.  Towards  its 
anterior  and  lower  part  it  presents  a  short  oblique  ridge,  called  the 
peroneal  spine  or  ridge,  which  separates  two  grooves.  The  upper 
groove  transmits  the  tendon  of  the  peroneus  brevis,  and  the  lower 
that  of  the  peroneus  longus.  Behind  and  a  little  above  this  spine 
there  is  a  small  tubercle,  about  the  centre  of  the  surface,  for  the 
middle  fasciculus  of  the  external  lateral  ligament  of  the  ankle-joint. 

The  OS  calcis  is  pierced  by  many  nutrient  foramina  for  offsets 
of  the  calcaneal  branches  of  the  posterior  tibial  and  external 
plantar,  and  the  internal  and  external  malleolar  branches  of  the 
anterior  tibial,  arteries. 

Articulations. — Superiorly  with  the  astragalus,  and  anteriorly 
with  the  cuboid. 

Structure. — The  structure  is  that  of  a  short  bone.  Some  of  the 
lamella  of  the  cancellated  tissue  arch  downwards  and  backwards 
from  the  large  postero-external  facet  on  the  superior  surface  to  the 
prominence  of  the  heel.  In  addition  to  these,  there  are  other 
lamellae  which  pass  in  an  antero-posterior  direction  just  above  the 
layer  of  compact  bone  which  forms  the  plantar  surface.  In  the 
region  of  the  groove  for  the  sinus  pedis,  especially  towards  the  outer 
part,  the  upper  compact  layer  is  thicker  than  elsewhere. 

Ossification. — The  os  calcis  ossifies  in  cartilage  from  one  primary,  and  one 

secondary,  centre.  The  primary  centre  appears  in  the  sixth  month  of  intra- 
uterine life.  The  secondary  centre  appears  in  the  tenth  year,  and  forms  a 
thin  epiphysial  scale  over  the  posterior  surface  of  the  tuber  calcis,  which  joins 
in  the  sixteenth  year.  This  epiphysis  includes  the  outer,  and  a  large  part  of 
the  inner,  tubercle  on  the  under  surface,  and  it  may  include  the  whole  of  the 
posterior  surface,  or  only  the  lower  two-thirds. 

The  Navicular  Bone. 

The  navicular  or  scaphoid  bone  is  distinguished  by  its  resemblance 
to  a  boat.  It  is  situated  on  the  inner  side  of  the  foot,  where  it  is 
placed  in  front  of  the  astragalus,  and  behind  the  three  cuneiform 


THE  BONES  OF  THE  LOWER  LIMB 


241 


bones.  It  is  compressed  from  before  backwards,  and  its  long 
axis  is  directed  inwards  and  downwards.  The  anterior  surface 
presents  a  large  convex  articular  surface,  divided  into  three  facets 
by  two  ridges  which  converge  inferiorly.  The  inner  facet,  for  the 
internal  cuneiform,  is  pyriform,  with  the  narrow  end  upwards. 
The  middle  facet,  for  the  middle  cuneiform,  is  triangular,  with  the 
truncated  apex  downwards.  The  outer  facet,  for  the  external  cunei- 
form, resembles  the  middle,  except  that  it  is  rather  shorter  and  has 
a  rounder  apex.  The  posterior  surface  is  characterized  by  a  large 
concave,  pyriform  facet  for  the  front  of  the  head  of  the  astragalus, 
its    narrow    end    being    directed    downwards    and    inwards.     The 


Dorsal  Surface 


Tuberosity!-. 


For  External  Cuneiform — \\ 


Posterior  Surface  for 

Head  of  Astragalus 


Spring  Tubercle  on 
Plantar  Surface 


For  Middle  Cuneiform 

_„For  Internal  Cuneiform 


Spring  Tubercle 

Fig.   147. — The  Right  Navicular  Bone. 
A,  Postero-superior  View  ;  B,  Antero-inferior  View. 

dorsal  surface,  extensive  and  rough,  is  sloped  downwards  and 
inwards.  The  plantar  surface,  narrow  and  rough,  gives  attachment 
to  the  inferior  calcaneo-navicular  or  'spring'  ligament,  and  about 
its  centre  there  is  usually  a  knob-like  projection,  called  the  spring 
tubercle.  The  external  surface  is  broad  and  rough,  and  it  sometimes 
presents  a  small  facet  for  the  cuboid,  contiguous  to  the  outer 
facet  on  the  anterior  surface.  The  inner  extremity  (prow  of  the 
boat)  is  inclined  downwards,  and  forms  a  stout,  round  projection 
on  the  inner  side  of  the  sole,  called  the  tuberosity,  which  gives 
insertion  to  the  principal  portion  of  the  tendon  of  the  tibialis 
posticus. 

16 


242 


A   MANUAL  OF  ANATOMY 


Articulations. — Posteriorly  with  the  astragalus,  anteriorly  with  the 
three  cuneiform  bones,  and  sometimes  with  the  cuboid  externally. 
Structure. — The  structure  is  that  of  a  short  bone. 

Variety. — The  tuberosity  sometimes  forms  a  separate  ossicle. 


The  Cuneiform  Bones. 

The  cuneiform  bones  are  three  in  number,  namely,  internal, 
middle,  and  external.  They  are  situated  between  the  navicular  and 
the  inner  three  metatarsal  bones,  and  are  characterized  by  their 

Dorsal  Surface 


Anterior  Surface  for  ist  Metatarsal.. 


-  Posterior  Surface  for  Navicular 
■  For  Tibialis  Anticus 


Posterior  Surface  for  Navicular — (-  _■; 


For  2nd  Metatarsal 


~"~--~.For  Middle  Cuneifom 

B 


Fig.  148. — The  Right  Internal  Cuneiform  Bone. 
A,  Internal  View  ;  B,  External  View. 

wedge  shape.    The  internal  cuneiform  is  the  largest,  and  the  middle 
is  the  smallest. 

The  internal  cuneiform  bone  is  situated  on  the  inner  side  of  the 
foot,  where  it  lies  with  the  narrow  end  of  the  wedge  upwards,  and  it 
supports  the  first  metatarsal.  The  dorsal  surface  is  narrow  and 
rough.  The  plantar  surface  is  thick  and  convex,  and  posteriorly 
it  presents  an  eminence  for  a  slip  of  the  tendon  of  the  tibialis 
posticus.  The  internal  surface  is  traversed  by  an  oblique  groove, 
directed  downwards   and  forwards,  for  the  tendon  of  the  tibialis 


THE  BONES  OF  THE  LOWER  LIMB  243 

anticus,  the  principal  portion  of  which  is  inserted  into  an  impression 
situated  at  the  lower  part  of  the  groove.  The  external  surface 
presents,  close  to  its  superior  and  posterior  borders,  an  L-shaped 
facet  for  the  middle  cuneiform,  at  the  anterior  extremity  of  which 
there  is  a  small  facet  for  the  inner  side  of  the  base  of  the  second 
metatarsal.  When  the  bone  is  held  in  its  proper  position,  the  L 
is  placed  thus  F  in  a  right  bone,  and  thus  1  in  a  left.  The  rest  of 
the  surface  is  concave  and  rough  for  strong  ligaments,  except  at  the 
lower  and  anterior  part,  where  it  gives  insertion  to  a  slip  of  the 
tendon  of  the  peroneus  longus.  The  anterior  surface  is  deep,  and 
presents  a  convex  reniform  facet  for  the  first  metatarsal,  the  concave 
border  being  directed  outwards.  The  posterior  surface,  much  smaller 
than  the  anterior,  is  characterized  by  a  concave  pyriform  facet  for 
the  navicular,  the  narrow  end  being  upwards. 

Articulations. — Posteriorly  with  the  navicular,  anteriorly  with  the 
first  metatarsal,  and  externally  with  the  middle  cuneiform  and 
second  metatarsal. 

Variety. — The  internal  cuneiform  may  be  divided  into  two  parts,  dorsal  and 
plantar. 

The  middle  cuneiform  bone  lies  with  the  broad  end  of  the  wedge 
upwards,    and    it   supports    the   second   metatarsal.      The    dorsal 

A 

Dorsal  Surface 


Anterior  Surface 
for  2nd  Metatarsal. 


For  Internal. 
Cuneiform 


Posterior  Surface  for . 
Navicular 
For  Kxternal 
Cuneiform 


Fig.   149. — The  Right  Middle  Cuneiform  Bone. 
A,  Internal  View  ;  B,  External  View. 

surface  is  rough  and  nearly  square.  The  plantar  surface,  also  rough, 
is  narrow,  and  gives  insertion  to  a  slip  of  the  tendon  of  the  tibialis 
posticus.  The  internal  stirface  presents,  close  to  its  superior  and  pos- 
terior borders,  an  L-shaped  facet  for  the  internal  cuneiform,  placcl 
thus  1  for  a  right  bone,  and  thus  T  for  a  left,  the  remainder  of  the 
surface  being  rough  and  ligamentous.  The  external  surf  a  e  has  a 
vertical  facet  posteriorly  for  the  external  cuneiform,  and  elsewhere 
it  is  rough  and  ligamentous.  The  anterior  and  posterior  'surfaces 
are  triangular  and  covered  by  cartilage,  the  former  articulating  with 
the  second  metatarsal,  and  the  latter  with  the  navicular.  They 
are  distinguished  from  each  other  in  the  following  manner  :  the 
anterior  surface  is  convex,  whilst  the  ]:)osterior  is  concave  ;  the 
apex  of  the  anterior  surface  is  more  pointed  than  that  of  the  pos- 

16 — 2 


244 


A   MANUAL  OF  ANATOMY 


terior  ;  and  the  posterior  surface  is  rather  broader  than  the  anterior, 
and  has  one  of  the  limbs  of  the  L  facet  close  to  it. 

Articulations. — Posteriorly  with  the  navicular,  anteriorly  with  the 
second  metatarsal,  internally  with  the  internal  cuneiform,  and 
externally  with  the  external  cuneiform. 

The  external  cuneiform  bone,  like  the  middle,  lies  with  the  broad 
end  of  the  wedge  upwards,  and  it  supports  the  third  metatarsal. 
The  doirsal  surface  is  rough,  quadrilateral,  and  elongated  from 
before  backwards.  The  plantar  surface,  also  rough,  is  narrow,  and 
gives  insertion  to  a  slip  of  the  tendon  of  the  tibialis  posticus.  The 
internal  surface  presents  a  vertical  facet  posteriorly  for  the  middle 
cuneiform,  and  two  semi-oval  facets  anteriorly  for  articulation  with 
the  proximal  pair  of  facets  on  the  outer  side  of  the  base  of  the  second 
metatarsal.  The  remainder  of  the  surface  is  rough  and  ligamen- 
tous. The  external  surface  has  a  large,  almost  circular,  facet  near 
the  postero-superior  angle   for  the   cuboid,  and  there  may  be   a 


For  2nd  Metatarsal 


Posterior  Surface 
for  Navicular 


For  Middle  Cuneiform 
' For  2nd  Metatarsal 


For  4th  Metatarsal 
(inconstant) 

For  Cuboid 


vAnterior  Surface 
for  3rd  Metatarsal 


Fig.   150. — The  Right  External  Cuneiform  Bone. 
A,  Internal  View  ;  B,  External  View. 


small  semi-oval  facet  at  the  antero-superior  angle  for  the  inner  side 
of  the  base  of  the  fourth  metatarsal,  but  this  facet  is  not  constant. 
Elsewhere  the  surface  is  rough  and  ligamentous.  The  anterior 
and  posterior  surfaces  are  triangular,  and  covered  by  cartilage, 
the  former  articulating  with  the  third  metatarsal,  and  the  latter 
with  the  navicular.  They  are  distinguished  from  each  other  in  the 
following  manner  :  the  anterior  facet  is  deeper  than  the  posterior, 
and  its  apex  is  more  pointed  ;  the  cartilage  of  the  anterior  surface 
extends  over  its  entire  length,  but  the  lower  part  of  the  posterior 
surface  is  non-articular ;  the  anterior  facet  is  slightly  concavo- 
convex  from  below  upwards,  but  the  posterior  is  concave,  and  it 
has  the  large,  almost  circular,  facet  on  the  external  surface  con- 
tiguous to  it. 

Articulations. — Posteriorly  with  the  navicular,  anteriorly  with  the 
third  metatarsal,  internally  with  the  middle  cuneiform  and  outer 
side  of  the  base  of  the  second  metatarsal,  and  externally  with  the 
cuboid,  and,  it  may  be,  with  the  inner  side  of  the  base  of  the  fourth 
metatarsal. 


THE  BONES  OF  THE  LOWER  LIMB  24$ 

Structure  of  the  Cuneiform  Bones. — The  structure  of  each  is  that 
of  a  short  bone. 

WTien  the  cuneiform  bones  are  in  position  their  posterior  surfaces 
are  on  the  same  transverse  plane,  but  the  anterior  surfaces  of  the 

Dorsal  Aspect 


For  4th  Metatarsal -V*l\ 
(inconstant) 


Anterior  Surface  of  External' 
Cuneiform  for  3rd  Metatarsal  ] 

For  2nd  Metatarsal' 


Anterior  Surface  o: 


I  Anterior  Surface  of  Internal 
Cuneiform  for  ist  Metatarsal 
For  2nd  Metatarsal 


Middle  Cuneiform 


for  2nd  Metatarsal 

Fig.  151. — The  Right  Cuneiform  Bones  (Antero-superior  View). 

internal  and  external  project  farther  forwards  than  that  of  the 
middle.  In  this  manner  a  recess  is  formed,  into  which  the  base 
of  the  second  metatarsal  bone  is  received. 


The  Cuboid  Bone. 

The  cuboid  bone  is  characterized  by  its  irregularly  cubical  shape, 
and  by  the  groove  and  ridge  on  its  plantar  aspect.  It  is  situated  on 
the  outer  border  of  the  foot,  where  it  lies  between  the  os  calcis 
and  the  fourth  and  fifth  metatarsal  bones.  The  anterior  surface 
has  its  cartilage  divided  by  a  vertical  ridge  into  two  facets — an 
inner  quadrilateral  for  the  fourth  metatarsal,  and  an  outer  triangular 
for  the  fifth  metatarsal.  The  posterinr  surface  presents  a  largo, 
somewhat  triangular,  facet,  narrow  towards  the  sole  and  deep  in- 
ternally, which  is  convex  from  above  downwards  and  outwards, 
and  concave  from  side  to  side.  It  articulates  with  the  os  calcis, 
and  its  internal  and  inferior  angle,  called  the  calcaneal  process, 
projects  backwards  for  a  little  beneath  that  bone.  Below  and 
inside  the  calcaneal  ])rocess  there  may  be  a  facet  for  the  head  of 
the  astragalus.  The  internal  surface,  which  is  extensive  and 
vertically  clLsposed,  presents  a  large,  almost  circular,  facet  for  the 
external  cuneiform,  near  the  centre  and  extending  to  the  dorsal 
surface.  Behind  this,  and  usually  continuous  with  it,  there  may  be 
a  small  facet  for  the  navicular,  the  remainder  of  the  surface  being 
rough   and  ligamentous.     The  external  surface,   which  is  really  a 


246 


A  MANUAL  OF  ANATOMY 


border,  is  very  short  and  narrow,  and  presents  a  notch  leading  to 
the  peroneal  groove  on  the  plantar  surface.  The  dorsal  surface 
is  rough,  and  is  directed  upwards  and  outwards.  The  plantar 
surface  presents  in  front  the  deep  peroneal  groove,  which  is  directed 
inwards  and  forwards,  and  lodges  the  tendon  of  the  peroneus  longus. 
Behind  the  groove  is  a  stout,  oblique  ridge  for  the  long  plantar 
ligament.  This  ridge  becomes  enlarged  externally  into  a  tubercle, 
which  is  covered  by  cartilage  on  its  anterior  and  outer  aspects  for 
the  play  of  the  sesamoid  cartilage,  or  bone,  usually  present  in  the 
tendon  of  the  peroneus  longus.  The  surface  behind  the  ridge  gives 
attachment  to  the  short  plantar  ligament,  a  slip  of  the  tendon  of 
the  tibialis  posticus,  and  some  fibres  of  the  flexor  brevis  hallucis, 
but  the  latter  may  spring  from  the  internal  surface. 


Dorsal  Surface 


Posterior  Surface  for 

Os  Calcis 


Calcaneal  Process' 


For  4th  Metatarsal, 


For  5th  Metatarsal 


For  External  Cuneiform 


Posterior  Surface 
for  Os  Calcis 


Fig.    152. — The    Right    Cuboid    Bone. 
A,  External  View  ;  B,  Internal  View. 

Articulations. — Posteriorly  with  the  os  calcis,  anteriorly  with  the 
fourth  and  fifth  metatarsal  bones,  internally  with  the  external 
cuneiform,  and  sometimes  with  the  navicular,  and  at  the  lower  and 
inner  angle  occasionally  with  the  astragalus. 

Structure. — ^The  structure  is  that  of  a  short  bone. 

The  tarsus  as  a  whole  is  convex  superiorly,  and  concave  interiorly, 
from  before  backwards  as  well  as  from  side  to  side.  The  part  in 
front  of  the  astragalus  and  os  calcis  constitutes  the  instep,  and  the 
entire  tarsus  forms  two  columns — an  inner,  comprising  the  astrag- 
alus, navicular,  and  three  cuneiform  bones,  and  an  outer,  representing 
the  OS  calcis  and  cuboid. 

Varieties. — The  number  of  tarsal  bones  is  sometimes  increased  to  eight, 
^s'hich  is  brought  about  in  one  or  other  of  the  following  ways  :  (i)  the  external 
tubercle  on  the  posterior  border  of  the  astragalus  may  form  a  separate  ossicle, 
called   the   os   trigonum  ;   (2)  the   tuberosity  of  the   navicular   may   form   a 


THE  BONES  OF  THE  LOWER  LIMB  247 

separate  ossicle  ;  (3)  the  internal  cuneiform  may  be  divided  into  two  parts, 
dorsal  and  plantar  ;  or  (4)  there  may  be  an  additional  ossicle  in  the  space  at 
the  antero-internal  part  of  the  os  calcis,  or  between  the  internal  cuneiform  and 
the  second  metatarsal. 

Ossification. — The  tarsal  bones  ossify  in  cartilage,  each  from  one  centre, 
(except  the  os  calcis,  which  has  one  primary,  and  one  secondary,  centre),  and 
at  the  following  periods  approximately  : 

Os  calcis,  6th  month  (intra-uterine).  External  cuneiform,  ist  year. 

Astragalus,  7th  month  (intra-uterine).  Internal  cuneiform,  3rd  year. 

Cuboid,  9th  month  (intra-uterine).  Middle  cuneiform,  4th  year. 

Navicular,  4th  year. 

For  the  secondary  centre  of  the  os  calcis,  see  page  240.  The 
external  tubercle  on  the  posterior  border  of  the  astragalus  has  some- 
times a  secondary  centre,  and  then  it  remains  separate  as  the  os 
trigonum. 

The  Metatarsus. 

The  metatarsus  is  composed  of  five  long  bones,  which  are  named 
numerically  from  within  outwards,  that  of  the  great  toe  being  the 
first.  Each  bone  is  divisible  into  a  shaft  and  two  extremities, 
proximal  and  distal.  The  shaft,  which  is  triangular,  is  massive  in 
the  first,  slender  and  much  compressed  laterally  in  the  second, 
third,  and  fourth,  and  compressed  from  above  downwards  in  the 
fifth.  Each  shaft,  except  that  of  the  first,  is  longitudinally  convex 
on  its  dorsal  aspect,  and  they  are  all  longitudinally  concave  on  their 
plantar  aspects.  The  shaft  presents  three  borders  and  three 
surfaces.  In  the  outer  four  bones  the  borders  are  two  lateral,  and 
a  plantar.  The  lateral  borders,  external  and  internal,  extend  from 
the  sides  of  the  proximal  end  or  base,  close  to  the  dorsal  aspect, 
to  the  dorsal  tubercle  on  either  side  of  the  distal  end  or  head,  and 
their  outline  is  sharp.  The  plantar  border,  round  behind,  but 
sharp  in  front,  extends  from  the  centre  of  the  plantar  aspect  of 
the  base  forwards  in  the  middle  line  to  near  the  head,  where  it 
bifurcates,  the  divisions  passing  to  the  cornua  on  the  plantar 
aspect  of  the  head.  The  dorsal  surface  lies  between  the  external 
and  internal  borders,  and  is  narrow.  Each  lateral  surface  is  situ- 
ated between  the  lateral  and  plantar  borders.  The  lateral  surfaces, 
which  are  extensive  and  sloped,  bound  the  interosseous  spaces,  and 
give  attachment  to  the  interosseous  muscles.  The  shaft  of  the  first 
metatarsal  has  its  borders  disposed  as  supero-external,  infero- 
external,  and  internal.  The  dorsal  surface  is  convex,  and  is  directed 
upwards  and  inwards.  The  plantar  surface  is  concave,  and  sup- 
ports the  tendon  of  the  flexor  longus,  and  the  flexor  brevis  hallucis. 
The  external  surface,  which  is  practically  vertical,  is  narrow  in  front, 
but  wide  behind. 

Tin;  heads  of  the  four  outer  metatarsal  bones  arc  much  compressed 
laterally.  The  cartilage.-  is  prolonged  more  on  the  plantar  than  on 
the  dorsal  aspect,  and  in  the  former  situation  it  ends  in  a  concave 


248 


A  MANUAL  OF  ANATOMY 


border,  surmounted  at  either  side  by  a  prominent  cornu.  On  either 
side  the  head  presents  a  dorsal  tubercle  and  plantar  depression 
for  the  lateral  metatarso-phalangeal  ligament.  The  head  of  the 
first  metatarsal  is  of  large  size,  and  elongated  transversely.  On 
its  plantar  aspect  it  presents  two  well-marked  grooves,  separated 
by  a  median  antero-posterior  ridge,  for  the  sesamoid  bones  in  the 
heads  of  insertion  of  the  flexor  brevis  hallucis. 

The  bases  of  the  metatarsal  bones  articulate  with  the  tarsus  and 
with  each  other,  except,  as  a  rule,  in  the  case  of  the  first,  and  they 
present  distinctive  characters  in  each  case. 

First  Metatarsal  Bone. — ^This  supports  the  great  toe,  and  is  the 
thickest  and  most  massive  of  the  series.  The  base  is  of  large  size, 
and  presents  a  concave  reniform  surface,  with  the  concavity  out- 
Head 


-=  Grooves  for  Sesamoid  Bones 


External  Surface 


For  2nd  Metatarsal 
(inconstant) 


Plantar  Surface 


Medullary  Foramen 


For  Tibialis  Anticus 
Foi  Peroneus  Longus 


Tuberosity 

Fig.  153. — The  First  Right  Metatarsal  Bone  (Plantar  View). 


wards,  for  the  internal  cuneiform.  Inferiorly  it  presents  a  pro- 
jection, called  the  tuberosity,  which  gives  insertion,  by  its  outer 
aspect,  to  the  principal  part  of  the  tendon  of  the  peroneus  longus, 
and  by  its  inner  aspect  to  a  slip  of  the  tendon  of  the  tibialis  anticus. 
There  is  usually  no  facet  on  its  outer  surface,  but  sametimes  it 
presents  one  for  the  second  metatarsal,  and  it  always  gives  origin 
to  the  inner  head  of  the  first  dorsal  interosseous. 

Articulations. — Posteriorly  with  the  internal  cuneiform,  and  some- 
times externally  with  the  second  metatarsal  ;  anteriorly  with  the 
first  phalanx  of  the  great  toe  ;  and  inferiorly  with  the  two  sesamoid 
bones. 

Second  Metatarsal  Bone. — ^This  supports  the  second  toe.  Its 
base  is  wedge-shaped,  with  the  broad  end  upwards.  It  recedes 
between  the  internal  and  external  cuneiform  bones,  and  posteriorly 


THE  BONES  OF  THE  LOWER  LIMB  249 

presents  a  concave  triangular  facet  for  the  middle  cuneiform.  On 
the  inner  side,  close  to  the  dorsal  aspect,  there  is  a  small  facet  for 
the  internal  cuneiform.,  and  sometimes  there  is  an  additional  facet, 
below  and  in  front  of  this,  for  the  first  metatarsal.  The  outer  side 
presents  two  facets,  dorsal  and  plantar,  separated  by  a  rough  antero- 
posterior groove,  each  of  these  being  subdivided  by  a  vertical 
ridge  into  two  semi-oval  facets.     There  are  thus  four  facets  in  all — 


Dorsal  Tubercle  - 
Plantar  Depression  ' 


External  Surfaci 


Medullary  Foramen 


For  3rd  Metatarsal" 


—  Internal  Surface 


--  For  ist  Metatarsal  (inconstant 
-  For  Internal  Cuneiform 


For  External  Cuneiform        For  Middle  L  ii  leifonii 

Fig    154. — The  Second  Right  Metatarsal  Bone. 
A,  External  View  ;   B,  Internal  View. 


a  posterior  pair  for  the  inner  side  of  the  external  cuneiform,  and  an 
anterior  pair  for  the  inner  side  of  the  base  of  the  third  metatarsal. 
The  })lantar  surface  of  the  base  gives  insertion  to  a  slip  of  the 
tendon  of  the  tibialis  posticus,  and  origin  to  a  portion  of  the  adductor 
obliquus  hallucis.  The  shaft  gives  i)artial  origin  to  the  first  and 
second  dorsal  interossei. 

Articulations. — Posteriorly  with  the  middle  cuneiform,  internally 
with  the  internal  cuneiform,  and  sometimes  with  the  first 
metatarsal,  externally  with  the  external  cuneiform  and  third 
metatarsal,  and  anteriorly  with  the  first  phalanx  of  the  second 
toe. 

Third  Metatarsal  Bone. — This  supports  the  third  toe.  The  base 
resembles  in  shajx;  that  of  the  second,  tlie  broad  end  being  uj^wards. 
Posteriorly  it  presents  a  triangular  facet,  concavo-convex  from 
above  downwards,  for  the  external  cuneiform.     The  inner  side  of 


2SO 


A   MANUAL  OF  ANATOMY 


the  base  presents  two  semi-oval  facets,  dorsal  and  plantar,  separ- 
ated by  a  rough  antero-posterior  groove,  for  the  anterior  pair  of 
facets  on  the  outer  side  of  the  base  of  the  second  metatarsal.  On 
the  outer  side  there  is  a  large  semi-oval  facet,  dorsally  placed, 
for  the  inner  side  of  the  base  of  the  fomth  metatarsal.  The 
plantar  surface  of  the  base  gives  insertion  to  a  slip  of  the  tendon 
of  the  tibialis  posticus,   and  origin   to  a  portion  of  the  adductor 


External  Surface 


Medullary  Foramen 


For  4th  Metatarsal.. 


Internal  Surface 


For  External  Cuneiform  For  2nd  Metatarsal 

Fig.   155. — The  Third  Right  Metatarsal  Bone. 
A,   External  View  ;  B,   Internal  View. 

obliquus  hallucis.  The  shaft  gives  origin  to  the  first  plantar 
interosseous,  and  partial  origin  to  the  second  and  third  dorsal 
interossei. 

Articulations. — Posteriorly  with  the  external  cuneiform,  internally 
with  the  second  metatarsal,  externally  with  the  fourth  metatarsal, 
and  anteriorly  with  the  first  phalanx  of  the  third  toe. 

Fourth  Metatarsal  Bone. — ^This  supports  the  fourth  toe.  The 
base  is  quadrilateral,  and  is  somewhat  broader  above  than  below. 
Posteriorly  it  presents  a  quadrilateral  facet  for  the  cuboid.  On 
the  inner  side  there  is  a  large  semi-oval  facet  for  the  third  meta- 
tarsal, and  this  is  sometimes  prolonged  to  the  extremity  of  the 
base,  thus  forming  an  additional  facet  for  the  outer  side  of  the 
external  cuneiform.  On  the  outer  side  there  is  a  large  semi- oval 
facet,  dorsally  placed,  for  the  inner  side  of  the  base  of  the  fifth 
metatarsal,  and  below  this  there  is  a  deep  rough  groove.  The 
plantar  surface  of  the  base  gives  insertion  to  a  slip  of  the  tendon 


THE  BONES  OF  THE  LOWER  LIMB 


251 


of  the  tibialis  posticus,  and  origin  to  a  portion  of  the  adductor 
obliquus  hallucis.     The  shaft  gives  origin  to  the  second  plantar 


External  Surface   - 
Medullary  Foramen  - 


Internal  Surface 


_| For  3rd  Metatarsal 


For  External  Cuneiform 
(inconstant) 


For  5th  Metatarsal  For  Cuboid 

Fig.  156. — The  Fourth  Right  Metatarsal  Bone. 
A,  External  view ;    B,  Internal  view. 

interosseous,  and  partial  origin  to  the  third  and  fourth  dorsal 
interossei. 

Articulations. — Posteriorly  with  the  cuboid,  internally  with  the 
third  metatarsal,  and  sometimes  with  the  external  cuneiform, 
externally  with  the  fifth  metatarsal,  and  anteriorly  with  the  first 
phalanx  of  the  fourth  toe. 

Fifth  Metatarsal  Bone. — ^This  supports  the  little  toe.  The  base 
is  elongated  from  side  to  side,  and  compressed  from  above  down- 
wards. Its  leading  characteristic  is  a  stout,  mammillary  process, 
situated  on  its  outer  aspect,  called  the  tuberosity,  which  is  directed 
outwards  and  backwards,  and  gives  insertion  to  the  tendon  of  the 
peroneus  brevis.  The  posterior  surface  presents  a  triangular  facet 
for  the  cuboid,  the  plane  of  which  is  inclined  inwards  and  forwards. 
This  facet  does  not  encroach  upon  the  tuberosity.  The  inner  sur- 
face presents  a  large  semi-oval  facet  for  the  outer  side  of  the  base  of 
the  fourth  metatarsal.  The  dorsal  surface,  which  is  rough  and 
slightly  convex,  gives  insertion,  as  a  rule,  to  the  tendon  of  the  per- 
oneus tertius.  The  plantar  surface,  which  is  rough  and  concave, 
gives  origin  to  the  flexor  brevis  minimi  digiti.  The  shaft  gives 
origin  to  the  third  plantar  interosseous,  and  partial  origin  to  the 
fourth  dorsal  interosseous. 

Articulations. — Posteriorly  with  the  cuboid,  internally  with  tlie 
fourth  metatarsal,  and  anteriorly  with  the  first  i)halanx  of  the  little 
toe. 

Each  metatarsal   bone  presents  a  medullary  foramen,   that   ot 


252 


A  MANUAL  OF  ANATOMY 


the  first   and  second,  and  usually  that  of    the  third  and  fourth, 
being  situated  on  the    outer   side  of  each   shaft,  whilst  that  of 


Internal  Surface. 
Medullary  Foramen  - 


For  4ta  Metatarsal 


Dorsal  Surface 


_  .For  Peroneus  Tertius 
..Tuberosity  for  Peroneus  Brevis 


For  Cuboid 

Fig.  157. — -The  Fifth  Right  Metatarsal  Bone  (Supero-internal  View). 

the  fifth  is  situated  on  the  inner  side.*  The  foramen  of  the  first 
and  the  canal  to  which  it  leads  are  directed  downwards  towards 
the  head  or  distal  end,  but  that  of  each  of  the  other  four  is  directed 


For  Middle  Cuneiform 
For  Internal  Cuneiform  .,  1 


For  External  Cuneiform 
/ 1\  For  Cuboid 


Tuberosity 


Tuberosity 

Fig.    158. — The    Bases    of    the    Right    Metatarsal    Bones 
(Posterior  View). 

Upwards  towards  the  base  or  proximal  end.  The  first  metatarsal 
receives  its  nutrient  artery  from  the  arteria  magna  or  princeps 
hallucis,  the  second  from  the  fourth  digital  artery,  the  third  usually 

*  Of  too  third,  and  an  equal  number  of  fourth,  metatarsal  bones  examined, 
73  third  metatarsals  had  the  medullary  foramen  on  the  outer  side,  and  27  on 
the  inner  side  ;  and  60  fourth  metatarsals  had  it  on  the  outer  side,  and  40  on 
the  inner  side. 


THE  BONES  OF  THE  LOWER  LIMB 


253 


from  the  third  digital,  and  the  fourth  and  fifth  from  the  second 
digital  artery. 

Structure. — The  structure  is  that  of  a  long  bone. 

Varieties. — (i)  The  tuberosity  on  the  outer  side  of  the  base  of  the  fifth 
metatarsal,  or  the  tuberosity  on  the  plantar  surface  of  the  base  of  the  first, 
may  form  a  separate  ossicle.  (2)  An  additional  ossicle  is  sometimes  met  with 
between  the  bases  of  the  first  and  second  metatarsals. 

The  metatarsus  as  a  whole  is  convex  on  its  dorsal  aspect  from 
side  to  side,  and  also  longitudinally.  The  transverse  convexity  is 
due  to  the  broad  ends  oi  one  bases  of  the  second,  third,  and  fourth 
metatarsals  being  directed  upwards.  On  its  plantar  aspect  it  is 
concave  from  side  to  side,  and  also  longitudinally.  All  five  bones  are 
nearly  parallel  with  each  other,  being  slightly  divergent  in  front. 
The  interosseous  spaces  are  as  in  the  hand,  the  first  being  the 
innermost. 


The  Phalanges. 

The  phalanges  are  fourteen  in  number — 
three  to  each  of  the  four  outer  toes,  and  two 
to  the  great  toe.  The  toes,  from  within  out- 
wards, are  called  great  toe  or  hallux,  second, 
third,  fourth,  and  fifth  or  little  toe.  In  their 
general  characters  the  phalanges  so  closely 
resemble  those  of  the  hand  that  a  detailed 
description  is  unnecessary.  The  phalanges  of 
the  great  toe,  called  proximal  and  distal,  are 
characterized  by  their  large  size  and  great 
length,  which,  with  the  length  of  the  first 
metatarsal  bone,  places  the  great  toe  on  a 
level  with  those  next  it.  The  first  phalanx  of 
the  four  outer  toes  is  characterized  by  being 
slender,  and  much  compressed  from  side  to 
side  over  its  shaft,  the  proximal  end  being  of 
large  size,  and  almost  triangular.  The  second 
phalanx  is  short,  and  compressed  from  above 
downwards.     The  ungual  phalanx  is  very  small. 


Fig.  159. 
The  Phalanges  of 
THE   Second  Toe 
(Plantar   View). 


Special  Muscular  Attachments. — The  base  of  the 
pro.ximal  ])halanx  of  the  great  toe,  which  presents  a 
tubercular  enlargement  at  either  side,  gives  insertion 
internally  to  the  abductor  liallucis  and  inner  head  of  the  flexor  brevis  hallucis  ; 
externally,  to  the  outer  head  of  the  flexor  brevis  hallucis,  adductor  obliquus 
hallucis.  and  adductor  transversus  hallucis ;  and  on  its  dorsal  surface  there  is  a 
rough  transverse  ridge  for  the  innermost  tendon  of  the  extensor  brevis  digi- 
torum.  The  base  of  the  ungual  phalanx  of  the  great  toe  gives  insertion,  on  its 
dorsal  surface,  to  the  extensor  jjroprius  hallucis,  and,  on  its  plantar  surface,  to 
the  flexor  longus  hallucis.  The  i:)ase  of  the  first  ])halanx  of  the  second  toe 
gives  partial  insertion  internally  to  the  first  dorsal  interosseous,  and  externally 
to  the  second  rior.sal  interosseous.  The  base  of  the  first  jihalanx  of  the  third 
toe  gives  partial  insertion  internally  to  the  first  plantar  interosseous,  and 
externally  to  the  third  dorsal  interosseous.     The  base  of  the  first  phalanx  of 


254 


A  MANUAL  OF  ANATOMY 


the  fourth  toe  gives  partial  insertion  internally  to  the  second  plantar  inter- 
osseous, and  externally  to  the  fourth  dorsal  interosseous.  The  base  of  the 
first  phalanx  of  the  fifth  toe  gives  partial  insertion  internally  to  the  third 
plantar  interosseous,  and  externally  insertion  to  the  abductor  minimi  digiti 
and  flexor  brevis  minimi  digiti.  The  second  and  ungual  phalanges  of  each 
of  the  four  outer  toes  give  insertion  to  extensor  and  flexor  tendons,  as  in  the 
case  of  the  corresponding  bones  of  the  four  inner  fingers. 

The  medullary  foramen  and  the  canal  to  which  it  leads  are, 
in  each  phalanx,  directed  towards  the  distal  end.  The  nutrient 
arteries  are  derived  from  the  corresponding  plantar  digital  arteries. 

Structure. — The  structure  of  each  phalanx  resembles  that  of  the 
corresponding  bone  in  the  hand. 

Varieties. — Ankylosis  of  the  ungual  and  second  phalanges  of  the  fifth  toe 
is  of  frequent  occurrence,  and  may  even  involve  those  of  other  toes,  up  to  and 
including  the  second. 

Sesamoid  Bones. — These  are  two  in  number,  and  are  of  large  size. 
They  are  associated  with  the  two  heads  of  insertion  of  the  flexor 
brevis  hallucis,  and  lie  on  the  plantar  aspect  of  the  head  of  the  first 
metatarsal  bone. 

Appears  in  the  loth  Year, 
and  joins  at  i6 


Appears  at  5th  Month  ., 
(intra-uterine) 

gth  Month  (intra-uterine v., 
ist  Year 


7th  Month 
(intra-uterine). 


4th  Year 

^**'^,..  4th  Year 

---3rd  Year 

Appears  between  4th  and  8th  Year 

and  joins  about  19 

-gth  Week  (intra-uterine) 

,  Appears  between  4th  and  8th  Year 
and  joins  about  ig 
Same  as  for  Metatarsals 

Epiphysis 
Primary  Centre 


Fig.  160. — Ossification  of  the  Bones  of  the  Foot. 


Ossification  of  Metatarsal  Bones  and  Phalanges. — Each  bone  ossifies  in 
cartilage  from  one  primary,  and  one  secondary,  centre,  which  closely  agree  with 
those  of  the  corresponding  bones  of  the  hand  in  their  disposition.  The  primary 
centres  for  the  shafts  appear  about  the  ninth  week  of  intra-uterine  life, 
whilst  the  secondary  centres  appear  between  the  fourth  and  eighth  year.  Each 
epiphysis  joins  its  shaft  about  the  nineteenth  year. 


THE  BONES  OF  THE  LOWER  LIMB 


25.5 


Tuber  Calcis 


Os  Calcis  (Neck). 

Tubercle  for  Middle  Fasciculus,. 
of  External  Lateral  Ligament 


Peroneal  Spine  or  Ridge_, 

Extensor  Brevis  Digitorum 

Cuboid 

Peroneus  Brevis- 

Peroneus  Tertius-- 
External  Cuneiform  ' 


——•Astragalus 


Navicular  (Scaphoid) 

Groove  for  Tibialis 

Amicus 
Internal  Cuneiform 

~"~«  Middle  Cuneiform 


-Innermost  Tendon  of 

Extensor  Brevis 

Digitorum 


-  Extensor  I'roprius 
Hallucis 


Extensor  Longus  Digitorum    -' 

Fig.   161. — Jhe  Right  Foot  (Dorsal  Surface). 


256  A  MANUAL  OF  ANATOMY 


The  Foot  as  a  Whole. 

The  foot  presents  two  arches,  longitudinal  and  transverse.  The 
posterior  pier  of  the  longitudinal  arch  is  formed  by  the  plantar 
aspect  of  the  tuber  calcis,  and  the  anterior  pier  by  the  heads  of  the 
metatarsal  bones.  The  arch  is  single  behind,  where  it  is  formed 
by  the  posterior  two- thirds  of  the  os  calcis,  but  it  is  divided  into 
two  pillars  in  front.  The  internal  pillar  is  formed  by  the  astragalus, 
navicular,  three  cuneiforms.,  and  inner  three  metatarsal  bones.  It 
is  more  elevated  from  the  ground  than  the  external,  and  has  to 
bear  greater  weight.  The  external  pillar  is  formed  by  the  anterior 
third  of  the  os  calcis,  cuboid,  and  outer  two  metatarsal  bones,  and 
is  nearer  the  ground  than  the  internal. 

The  transverse  arch  is  most  conspicuous  at  the  tarso-metatarsal 
articulations,  and  is  due  to  the  broad  aspects  of  the  middle  and 
external  crmeiforms,  and  the  broad  aspects  of  the  wedge-shaped 
bases  of  the  second,  third,  and  fourth  metatarsal  bones  being 
dorsally  placed. 

The  arches  serve  the  following  purposes  :  they  give  strength  and 
elasticity  to  the  foot ;  they  protect  the  structures  contained  in  the 
sole  ;  and  they  permit  of  the  heel-to-toe  movement  in  walking, 
which  is  characteristic  of  man. 

The  foot  presents  iwo  surfac:s,  dorsal  and  plantar,  and  two 
borders,  internal  or  tibial,  corresponding  with  the  great  toe,  and 
external  or  fibular,  corresponding  with  the  little  toe.  On  its  plantar 
aspect  it  presents  the  following  projections  :  the  inner  and  outer 
tubercles  on  the  under  surface  of  the  tuber  calcis  ;  the  anterior 
tubercle  of  the  os  calcis ;  the  tuberosity  of  the  navicular ;  the 
eminence  on  the  plantar  surface  of  the  internal  cuneiform  bone  ; 
the  tuberosity  on  the  under  surface  of  the  base  of  the  first  meta- 
tarsal bone  (the  three  last  being  along  the  inner  aspect  of  the  sole) ; 
and  the  tuberosity  on  the  outer  side  of  the  base  of  the  fifth  meta- 
tarsal bone,  which  is  on  the  outer  border  of  the  foot.  All  these 
projections,  with  their  attachments,  have  been  already  described 
in  connection  with  each  individual  bone. 


APPROXIMATE  HOMOLOGIES  OF  THE  BONES  OF  THE  LIMBS. 

Upper  Limb.  Lower  Limb. 

I.  Shoulder  Girdle  and  Pelvic  Girdle. 

Scapula      -         -         -  =  Ilium. 

Coracoid     -         -         -  =  Ischium. 

Precoracoid  of   mono-  'I  _  n         w 

tremata  and  reptiles  /  ~  us  puDis. 

Clavicle      -         -         -  Absent. 

(If,  however,  the  clavicle  is  the  morphological  representative  of   the  pre- 
coracoid of  monotremata  and  reptiles,  then  it  is  homologous  with  the  os  pubis.) 


THE  BONES  OF  THE  LOWER  LIMB 


257 


Tuber  Calcis 


Outer  Head  of  Abductor 

Hallucis 
Flexor  Brevis  Digitoruni 

Inner  Head  of  Flexor     _  _^_ 
Accessorius 

Sustentaculum  Tali 


Tibialis  Posticus 
Peroneus  Longus 


Tibialis  Amicus 


Abductor  Hallucis  and 
Inner  Head  of  Flexor 
Brevis  Hallucis 
Outer   Head  of  Flexor 
Brevis  Hallucis,  Adduc- 
tor  Obliquus   Hallucis, 
and   Adductor  Trans- 
versus  Hallucis 


Flexor  Longus  Halluci 


Abductor  Minimi  Di^iti 


Outer  Head  of  Flexor 
Accessorius 


Flexor  Brevis  Hallucis 


Tuberosity  of  5th 
Metatarsal  and 
Peroneus  Brevis 

■  Flexor  Brevis 
Minimi  Digiti 


Adductor  Obliquus 
Hallucis 


-.Abductor  Minimi 
Digiti  and  Flexor 
Brevis  Minimi 
Digiti 


Flexor  Brevis  Digitoruni 


Flexor  Longus  Digitorum 


Fig.   162. — The  Right  Foot  (Plantar  Surface). 


17 


258  A  MANUAL  OF  ANATOMY 

Upper  Limb.  Lower  Limb. 

Special  Homologies  of  Scapula  and  Ilium  (Flower). 

Scapula.  Ilium. 

Inferior  angle        -  -  =  Anterior  superior  spine. 

Superior  angle      -  -  =  Posterior  superior  spine. 

Base    -         -         -  -  =  Crest. 

Axillary  border    -  -       ~  =.  Anterior  border. 

Superior  border    -  -  =  Posterior  border. 

Supraspinous  fossa  -  =  Sacral  surface. 

Infraspinous  fossa  -  =  Iliac  fossa. 

Spine  and  acromion  -  =  Ilio-pectineal  Line. 

Subscapular  fossa  -  =  Gluteal  surface  (dorsum  ilii). 

Glenoid  cavity     -  -  =  Cotyloid  cavity. 

II.  Arm,  Forearm,  Thigh,  and  Leg. 

Humerus-  -  =  Femur. 

Absent     -  -  — -  Patella. 

Radms     -  -  =  Tibia. 

Ulna          -  -  =  Fibula. 

Special  Homologies  of  Humerus  and  Femur. 

Humerus.  Femur. 

Great  tuberosity      -         -  =  Small  trochanter. 

Small  tuberosity      -         -  =  Great  trochanter. 

"^"capUeLT-"*'!   ""}      =         Internal  condyle. 
Internal    epicondyle    and  )  -c-   *         i         j   i 

trochlea        -         -         -/      =  External  condyle. 

III.  Hand  and  Foot. 

Hand.  Foot. 

Carpus      -         -  .  =  Tarsus. 

Metacarpus       -  -  =  Metatarsus. 

Digital  phalanges  -  =  Digital  phalanges. 

Pollex       -         -  -  =  Hallux, 

Homologies  of  Carpus  and  Tarsus. 

Carpus.  Tarsus. 

Scaphoid  (except  the  part  re-  "l 

presented  by  the  embryonic  |       _  .  , 

supernumerary      cartilage),  i       ~'  Astragalus. 

and  semilunar     -         -         -  j 
Cuneiform  or  pyramidal  -         -  =  Os  calcis. 

(The  pisiform  is  generally  regarded  as  the  rudiment  of  a  suppressed  digit.) 

The    part    of     the     scaphoid  ] 

formed   by    the    embryonic   -      =  Navicular  or  scaphoid, 

supernumerary  cartilage      -  J 


THE  BONES  OF   THE  LOWER  LIMB  259 

(In  apes  and  water-tortoises  there  is  an  additional  carpal  bone,  called  the 
OS  centrale,  which  represents  the  navicular  of  the  tarsus.) 

Trapezium  -  -  =  Internal  cuneiform. 

Trapezoid  -  -  =  ^liddle  cuneiform. 

Os  magnum  -  -  =  External  cuneiform. 

Unciform  -  -  =  Cuboid. 


Development  of  the  Bones  of  the  Limbs. 

The  pectoral  and  pelvic  limbs  appear  about  the  fourth  wetk  as  outgrowths 
or  limb-buds,  which  spring  at  either  side  from  a  ridge  of  the  mesoblast  near  the 
outer  margins  of  the  mesoblastic  somites.  These  buds  are  covered  by  epiblast, 
and  each  receives  prolongations  from  the  muscle -plates  of  the  contiguous 
somites,  which  prolongations  give  rise  to  the  muscles,  as  well  as  processes  from 
the  spinal  cord,  which  give  rise  to  the  nerves.  In  their  development  the  limb 
bones  pass  through  the  same  stages  as  the  vertebrae,  namely,  membranous,  car- 
tilaginous, and  osseous.  The  mesoblast  in  the  centre  of  each  limb-bud  forms 
the  membranous  stage.  About  the  fifth  week  chondrification  takes  place, 
and  constitutes  the  cartilaginous  stage.  A  little  later  osseous  centres  appear, 
and  the  process  of  ossification  commences.  The  mesoblastic  tissue  between 
the  cartilaginous  frameworks  of  the  bones  assumes  a  hollow  condition,  and  so 
the  joint-cavities  are  formed,  the  synovial  membranes  and  ligaments  being 
developed  from  the  surrounding  mesoblast. 


17 — 2 


ARTHROLOGY 

An  articulation  or  joint  is  the  connection  between  two  or  more 
parts  of  the  skeleton  in  the  recent  condition.  In  most  joints  the 
parts  are  osseous,  but  in  certain  cases  cartilage  forms  the  basis. 
The  manner  in  which  the  parts  are  connected  and  the  amount  of 
movement  allowed  between  them  vary,  and  joints  are  accordingly 
divided  into  three  classes,  namely,  synarthrosis,  amphi arthrosis, 
and  diarthrosis. 

Synarthrosis. — This  is  direct  union,  there  being  only  a  small 
amount  of  intervening  tissue  without  any  joint  cavity,  and  the  joint 
is  immovable.  There  are  two  varieties  of  this  class — synchondrosis 
and  suture. 

1.  Synchondrosis.- — In  this  joint  a  thin  plate  of  hyaline  cartilage 
intervenes  between  the  component  parts,  as,  for  example,  between 
the  diaphysis  or  shaft  and  epiphyses  of  a  long  bone.  It  is  essentially 
a  temporary  joint. 

2.  Suture. — In  this  variety  the  bones  are  separated  by  a 
small  amount  of  fibrous  tissue,  which  is  continuous  with  the  peri- 
osteum. Such  joints  are  only  met  with  in  the  skull.  There  are 
three  forms  of  suture,  called  true,  false,  and  grooved.  When  the 
margins  of  the  bones  present  a  number  of  projections  with  inter- 
vening depressions,  so  that  they  become  closely  interlocked,  the 
suture  is  called  true.  When  the  opposed  margins  are  more  or  less 
flat,  so  that  there  is  merely  apposition  without  interlocking,  the 
suture  is  spoken  of  as  false  When  one  margin  presents  a  ridge  and 
the  other  a  cleft  into  which  the  ridge  is  received,  it  is  known  as  a 
grooved  suture. 

True  sutures  are  of  three  kinds — serrated,  dentated,  and  limbous. 
In  the  serrated  suture  the  margins  of  the  bones  are  saw-like,  as  in 
the  frontal  suture ;  in  the  dentated  suture  the  margins  present 
projections  like  teeth,  as  in  the  interparietal  suture ;  and  in  the 
limbous  suture  the  projections  on  the  margins  of  the  bones 
are  bevelled  so  that  they  overlap,  as  in  the  fronto  -  parietal 
suture. 

False  sutures  are  of  two  kinds — squamous  and  harmonic.  In  the 
squamous  suture  the  margins  are  bevelled  so  that  one  overlaps  the 
other,  as  in  the  squamo-parietal  suture.  In  the  harmonic  suture 
the  surfaces,  which  are  rough,  are  in  direct  apposition,  as  between 

260 


ARTHROLOGY  261 

the  superior  maxilla.  In  the  grooved  suture  a  ridge  on  one  bone 
is  received  into  a  cleft  on  another.  Such  a  suture  is  known  as 
schindyksis,  and  it  is  exemphfied  in  the  articulation  between  the 
rostrum  of  the  sphenoid  and  the  vomer. 

Amphiarthrosis.- — In  this  class  the  opposed  surfaces  are  connected 
either  b\-  a  disc  of  fibro-cartilage,  or  by  an  interosseous  hgament, 
and  the  joint  is  partially  movable.  When  the  connecting  medium 
is  a  disc  of  fibro-cartilage  the  name  of  symphysis  is  given  to  the  joint. 
as  between  the  bodies  of  the  vertebras,  the  bodies  of  the  pubic  bones, 
and  between  the  presternum  and  mesostemum.  When  the  con- 
necting medium  is  an  interosseous  ligament  the  joint  is  called  syndes- 
mosis, as  in  the  inferior  tibio-fibular  articulation.  Union  by  means 
of  an  interosseous  membrane  is  also  a  form  of  syndesmosis. 

Diarthrosis. — While  there  is  more  or  less  continuitv  at  a  syn- 
arthrosis and  an  amphiarthrosis,  there  is  none  at  a  diarthrosis.  The 
articular  ends  of  the  bones  are  free,  and  the  joint  is  freely  movable. 
The  ends  of  the  bones  are  smooth  and  pohshed,  being  covered  by 
articular  cartilage;  they  are  connected  by  ligaments;  and  the 
interior  of  the  joint  is  lined  with  a  synovial  membrane,  except  over 
the  articular  cartilages.  Ihis  membrane  secretes  the  synovia, 
which  lubricates  all  parts  of  the  interior.  There  are  five  varieties 
of  diarthrosis. 

1.  Enarthrosis  or  Ball-jnd-socket  Joint. — In  this  variety  one 
articular  end  is  spherical,  and  the  other  is  hohowtd  into  a  socket 
for  its  reception,  as  in  the  shoulder-  and  hip-joints. 

2.  Condylarthrosis  or  Condylar  Joint.— This  is  akin  to  enarthrosis. 
One  articular  end  has  the  form  of  a  condyle,  and  the  other  presents  a 
shallow  cavity,  as  in  the  metacarpo-  and  metatarso-phalangeal  joints. 

3.  Trochlearthrosis,  Ginglymus,  or  Hinge  Joint. — In  this  variety 
one  articular  end  has  the  form  of  a  trochlea  or  pulley,  and  the  other 
is  so  shaped  as  to  adapt  itself  to  it,  as  in  the  elbow-  and  ankle-joints. 

4.  Arthrodia  or  Gliding  Joint. — In  this  joint  the  surfaces  are  almost 
plane,  or  in  some  cases  concavo-convex,  as  in  the  joints  between 
the  articular  processes  of  vertebrae,  and  the  carpal  and  tarsal  joints. 
Under  this  variety  is  to  be  included  the  reciprocal  or  saddle  joint, 
where  the  articular  surfaces  are  saddle-shaped  and  mutually  adapt 
themselves  to  each  other,  as  between  the  trapezium  and  the  first 
metacarpal  bone. 

5.  Trochoides  or  Pivot  Joint.— Iii  this  joint  one  articular  end 
forms  a  pi\ot,  and  the  other  is  so  arranged  as  to  rotate  around  it,  as 
between  the  atlas  and  the  odontoid  process  of  the  axis. 

Ligaments. — 1  hese  are  composed  of  white  fibrous  tissue,  and,  as 
their  name  implies,  they  bind  the  bones  together.  At  a  diarthrosis 
their  chief  use  is  to  control  movement,  the  bones  being  maintained 
in  position  by  the  muscles  and  atmospheric  pressure.  At  their  attach- 
ments they  are  intimately  associated  with  the  periosteum.  When  the 
fibrous  tissue  is  arranged  continuously  round  the  joint  the  ligament 
is  called  a  capsular  ligament.  In  other  cases  the  tissue  is  disposed 
as  round  cords,  and  in  a  third  variety  it  forms  flattened  bands. 


262  A   MANUAL  OF  ANATOMY 

Synovial  Membranes. — These  membranes  are  so  named  because 
they  secrete  a  fluid,  viscid  hke  white  of  egg,  which  is  cahed  synovia. 
They  serve  to  diminish  friction  and  so  facihtate  movement  Their 
situations  are  therefore  associated  with  movable  structures,  such  as 
joints,  gliding  tendons,  and  the  integument  over  bony  projections. 
Accordingly  there  are  three  kinds  of  synovial  membrane — namely, 
articular,  tendon  or  vaginal,  and  bursal. 

The  articular  synovial  membranes  line  the  interior  of  diarthrodial 
joints,  except  where  there  is  articular  cartilage,  and  they  stop  at 
the  margin  of  this  cartilage.  In  some  joints  they  give  rise  to  folds, 
some  of  which  contain  adipose  tissue.  Such  folds  are  known  as 
Haversian  mucilaginous  glands. 

The  tendon  or  vaginal  synovial  membranes,  also  known  as  synovial 
sheaths,  invest  those  tendons  which  have  to  glide  within  fibrous 
sheaths  They  are  met  with  around  the  ankle,  particularly  behind 
the  external  and  internal  malleoli,  and  upon  the  palmar  aspect  of 
the  fingers. 

The  bursal  synovial  membranes,  commonly  called  synovial 
bursae,  are  synovial  sacs  which  are  situated  between  the  integument 
or  a  muscle  and  some  bony  projection.  They  may  be  deep- 
seated  or  subcutaneous.  T  he  dsep-seated  hurscB  are  situated  between 
a  muscle,  or  its  tendon,  and  the  contiguous  bone, — e.g.,  the  tendon 
of  the  biceps  brachii  and  the  anterior  part  of  the  bicipital  tuberosity 
of  the  radius.  The  subcutaneous  Htrsce  are  placed  beneath  the  in- 
tegument, which  they  separate  from  some  bony  projection — e.g., 
the  prepatellar  bursa. 

Structure. — A  synovial  membrane  consists  of  connective  tissue,  which  is 
destitute  of  an  endothelial  lining  properly  so  called.  At  intervals  it  may  pre- 
sent scattered  groups  of  branched  cells,  but  these  are  not  endothelial.  There 
are  many  capillary  bloodvessels,  and  lymphatic  vessels  are  described  as  being 
present.  The  nerves  are  described  as  terminating  in  corpuscles  of  the  nature 
of  end-balls,  in  a  plexiform  manner,  and  in  Pacinian  corpuscles.    - 

Development.  —  Synovial  membranes  are  developed  from  the  axial 
mesenchyme  of  the  limb-buds,  in  the  intervals  between  contiguous  bones, 
which  are  being  formed  from  that  mesenchyme. 

Interarticular  Fibro-cartilages. — These  are  met  with  in  certain 
joints  either  in  the  form  of  plates  separating  the  articular  ends,  or 
as  bands  placed  around  cavities,  which  they  serve  to  deepen,  or 
around  flat  surfaces,  which  they  render  concave.  They  are  known 
as  menisci.  When  the  fibro-cartilage  takes  the  form  of  a  plate  it 
is  spoken  of  as  an  interarticular  meniscus.  Such  occur  at  the 
temporo-mandibular,  sterno-clavicular,  and  radio-carpal  joints. 
They  act  as  buffers  to  break  shock,  and  the}^  compensate  for 
irregularities  of  the  opposed  surfaces.  When  the  fibro-cartilage  is 
limited  to  the  margin  of  a  cavity,  or  the  circumference  of  a  surface, 
it  is  called  a  marginal  meniscus,  such  as  the  glenoid  ligament  of 
the  shoulder- joint,  the  cotyloid  ligament  of  the  hip-joint,  and  the 
semilunar  fibro-cartilages  of  the  knee-joint. 

Movements.— The  different  kinds  of  movement  at  diarthrodial 
joints  are  angular,  circumduction,  rotation,  and  gliding. 


ARTHROLOGY  263 

Angular  Movement. — This  increases  or  diminishes  the  angle 
between  two  or  more  bones.  When  it  takes  place  in  a  forward  and 
backward  direction,  so  as  to  bend  or  straighten  a  joint,  it  is  spoken  of 
as  flexion  and  extension.  When  it  takes  place  laterally,  away  from 
or  towards  the  median  plane  of  the  body,  it  is  called  abduction  and 
adduction.  In  the  case  of  the  hand  the  median  line  from  or  towards 
which  abduction  and  adduction  take  place  is  a  line  passing  through 
the  centre  of  the  middle  finger,  and  in  the  case  of  the  foot,  through 
the  centre  of  the  second  toe. 

Circumduction. — This  consists  of  the  four  forms  of  angular 
movement,  occurring  successively  in  such  sequence  as  flexion, 
abduction,  extension,  and  adduction.  It  occurs  at  ball-and-socket 
and  condylar  joints,  and  during  the  movement  a  part  of  the  limb 
describes  a  cone,  the  apex  of  which  is  formed  by  the  proximal  end 
at  the  moving  joint,  whilst  the  base  is  described  by  the  distal  end. 

Rotation. — This  is  movement  of  a  bone  round  its  axis  without 
much  disturbance  of  its  position.  It  occurs  at  enarthrodial  and 
trochoidal  joints,  and  also  at  the  knee-joint,  which  is  a  ginglymus. 

Gliding  Movement. — This  consists  of  a  simple  to-and-fro  or  sliding 
movement  of  two  articular  surfaces,  as  between  the  articular  surfaces 
of  vertebrae,  and  at  the  carpal  and  tarsal  joints.  When  the  gliding 
is  combined  with  a  certain  amount  of  turning  or  rolling,  so  as  to 
bring  different  parts  of  the  articular  surfaces  successively  into 
contact  in  different  positions  of  the  joint,  the  movement  is  known 
as  coaptation,  as  at  the  femoro-patellar  joint. 

A  description  of  the  different  articulations  will  be  found  in  con- 
nection with  the  regions  to  which  they  belong. 


THE    UPPER   LIMB 


THE   BACK. 


Landmarks. — The  middle  line  of  the  neck  presents  a  median  furrow, 
called  the  nuchal  groove,  which  lies  over  the  line  of  the  ligamentum 
nuchse.  It  is  due  to  the  shortness  of  most  of  the  cervical  spinous 
processes  and  the  prominence  at  either  side,  caused .  principally 
by  the  complexus  muscle.  At  the  upper  end  of  this  groove  the 
strong  bifid  spine  of  the  axis  may  be  felt  by  sinking  the  finger 
deeply,  but  the  spines  of  the  third,  fourth,  and  fifth  cervical  vertebrae 
cannot  be  detected,  as  these  fall  short  of  the  surface  so  as  to  allow 
of  dorsal  flexion  of  the  neck.  At  the  lower  end  of  the  groove  the  , 
spine  of  the  seventh  cervical  or  vertebra  prominens  can  readily  be 
felt,  and  usually  also  that  of  the  sixth,  and  succeeding  to  these  are 
the  thoracic  and  lumbar  spines.  The  spine  of  the  first  thoracic 
vertebra  is,  as  a  rule,  the  most  conspicuous  of  the  series.  Along  the 
middle  line  of  the  thoracic  and  lumbar  regions  there  is  an  elongated 
furrow,  called  the  spinal  groove,  which  is  produced  by  the  promi- 
nence formed  by  the  erector  spinae  on  either  side.  This  groove 
is  best  marked  in  the  lower  thoracic  and  upper  lumbar  regions,  and 
it  subsides  about  the  level  of  the  third  sacral  spine.  The  outline 
of  the  scapula  may  be  made  out,  unless  in  very  muscular  persons. 
It  will  be  found  to  extend  from  the  second  to  the  seventh  rib,  and  the 
spine  and  acromion  process  are  usually  readily  felt.  The  root  of 
the  spine  is  on  a  level  with  the  third  thoracic  spine,  and  the 
inferior  angle  coincides  with  the  seventh  rib.  The  crest  of  the 
ilium  can  be  felt  at  the  lower  part  of  the  back,  its  greatest  promi- 
nence being  on  a  level  with  the  fourth  lumbar  spine. 

Fascia. — The  superficial  fascia  is  thick,  granular,  and  fatty,  and 
in  it  the  cutaneous  nerves  and  vessels  are  met  with.  The 
deep  fascia  is  thin  and  membranous,  but  firm.  It  contains  no  fat, 
and  forms  sheaths  for  the  muscles. 

Cutaneous  Nerves. — These  are  most  readily  met  with  at  the 
level  of  the  deep  part  of  the  superficial  fascia,  and  the  cutaneous 
vessels  serve  as  the  best  guide  to  them.  They  are  derived  from 
the  posterior  primary  divisions  of  the  spinal  nerves,  which,  with  a 
few  exceptions,  divide  each  into  an  external  and  internal  branch. 

264 


THE  UPPER  LIMB 


265 


In  the  thoracic  region  the  internal  branches  of  the  upper  six  nei-ves 
become  cutaneous  near  the  spines  of  the  vertebrae,  and  then  turn 
outwards  in  the  integument.  The  branch  of  the  second  is  character- 
ized by  its  great  length,  and  it  can  be  traced  well  outwards  over 
the  scapula.  The  external  branches  of  the  upper  six  thoracic 
nerves  end  in  the  muscles.  The  internal  branches  of  the  lower  six 
thoracic  nerves  are  muscular,  and  the  external  branches  become 


'I  lapezius 


Teres  Major 


—Triceps 


Latissimus  Dorsi 

Obliqjus  Exteriius  Abdominis 

v\  .Gluteal  Cutaneous  Branches  from  first  three 

-ii '  Lumbar  Nerves 


jhiteus  Mediiis 


(iluteus  Maximus 


Fig.    163. — The  Superficial  Dissection  of  the  Back. 

cutaneous  along  the  course  of  the  angles  of  the  ribs.  In  the  lumbar 
region  the  internal  branches  end  in  the  muscles.  The  external 
branches  of  the  first  three  nerves  furnish  cutaneous  offsets  which 
descend  over  the  iliac  crest  in  front  of  the  outer  border  of  the 
erector  spinse  to  the  gluteal  integument,  sup})lying  in  their  course 
the  integument  of  the  lumbar  region.  The  external  branches  of 
the  lower  two  nerves  end  in  the  deep  muscles.     In  all  cases  the 


266  A   MANUAL  OF  ANATOMY 

tribution  of  the  cutaneous  nerves  is  at  a  lower  level  than  their 
origin. 

The  cutaneous  arteries  which  accompany  the  cutaneous  nerves 
of  the  thoracic  and  lumbar  regions  are  derived  from  the  dorsal 
branches  of  the  intercostal  and  lumbar  arteries. 

Muscles.  Trapezius. — ^This  muscle  is  so  named  because,  along 
with  its  fellow,  it  presents  a  four-sided  appearance  like  a  table. 
The  two  muscles  have  also  a  resemblance  to  a  monk's  hood  or  cowl ; 
hence  the  name  cucullaris. 

Origin. ^{i)  The  inner  third  of  the  superior  curved  line  of  the 
occipital  bone,  and  the  external  occipital  protuberance ;  (2)  the 
ligamentum  nuchse ;  and  (3)  the  spinous  processes  and  supra- 
spinous ligaments  of  the  last  cervical,  and,  as  a  rule,  all  the  thoracic 
vertebrae.  The  origins  of  the  two  muscles  are  markedly  tendinous 
between  the  second  cervical  and  third  thoracic  spines,  where  they 
give  rise  to  an  elliptical  area,  widest  opposite  the  sixth  cervical 
spine. 

Insertion. — (i)  The  posterior  border  of  the  outer  third  of  the 
clavicle ;  (2)  the  inner  border  of  the  acromion  process,  and  upper 
lip  of  the  posterior  border  of  the  spine,  of  the  scapula ;  and  (3)  the 
tubercle  which  projects  at  the  inner  end  of  the  upper  lip  of  the  spine 
near  the  root.  The  lower  fibres  end  in  a  special  tendon  which 
glides  over  the  triangular  surface  at  the  root  of  the  spine,  being 
separated  from  it  by  a  synovial  bursa. 

Nerve-supply. — (i)  The  spinal  accessory  nerve  (spinal  portion), 
and  (2)  branches  from  the  cervical  plexus,  which  are  derived  from 
the  anterior  primary  divisions  of  the  third  and  fourth  cervical  nerves. 
The  nerves  enter  the  deep  surface  of  the  muscle  after  passing  beneath 
its  anterior  border  a  little  above  the  clavicle,  and  the  spinal  acces- 
sory, having  become  connected  with  the  spinal  nerves,  can  be  traced 
over  nearly  the  whole  extent  of  its  deep  surface,  where  it  lies  about 
2  inches  from  the  spines  of  the  vertebrae. 

Blood-siipply. — ^There  is  one  specially-named  artery,  called  the 
superficial  cervical,  which  is  a  branch  of  the  transverse  cervical, 
and,  like  the  nerves,  enters  the  deep  surface  of  the  muscle. 

The  upper  fibres  of  the  muscle  are  directed  downwards,  outwards, 
and  forwards  ;  the  middle  fibres  pass  more  or  less  horizontally 
outwards  ;  and  the  lower  fibres  pass  upwards  and  outwards. 

Action. — ^The  upper  fibres,  acting  from  their  origin,  elevate  the 
outer  end  of  the  clavicle  and  the  point  of  the  shoulder.  Acting 
from  their  insertion  they  extend  the  head  and  incline  the  neck 
towards  the  same  side,  the  face  being  directed  towards  the  opposite 
side.  The  middle  fibres  approximate  the  scapula  to  the  spine,  and 
the  lower  fibres  draw  it  downwards  and  inwards,  both  of  these  sets 
of  fibres  also  producing  rotation  of  the  bone,  so  as  to  elevate  the 
point  of  the  shoulder.  The  entire  muscle  draws  the  scapula  to  the 
spine,  and  produces  a  certain  amount  of  rotation  of  the  bone,  the 
point  of  the  shoulder  being  raised,  as  in  the  act  of  shrugging  the 
shoulders. 


THE   UPPER  LIMB  267 

Ligamentum  Nuchas. — ^This  is  a  fibrous  band,  or  intermuscular 
septum,  which  occupies  the  median  line  of  the  neck.  Its  superficial 
fibres  are  attached  above  to  the  external  occipital  protuberance, 
and  below  to  the  spine  of  the  seventh  cervical  vertebra.  Its  deep 
fibres  are  attached  to  the  external  occipital  crest,  and  to  the  spines 
of  cervical  vertebrae  from  the  second  to  the  sixth  inclusive.  They 
also  extend  into  the  interspinous  intervals  between  the  inter- 
spinales  muscles,  where  they  represent  interspinous  ligaments. 

Latissimus  Dorsi — Origin. — (i)  The  spinous  processes  and  supra- 
spinous ligaments  of  the  lower  six  thoracic  vertebrae;  (2)  the  posterior 
lamina  of  the  lumbar  aponeurosis,  through  means  of  which  it  is 
attached  to  the  lumbar  and  sacral  spines,  and  the  posterior  fourth  of 
the  outer  lip  of  the  iliac  crest ;  (3)  the  outer  lip  of  the  iliac  crest  a 
little  behind  the  centre  for  about  2  inches  ;  (4)  the  outer  surfaces 
of  the  last  three  or  four  ribs  external  to  their  angles  by  fleshy  slips, 
which  interdigitate  with  slips  of  the  obliquus  externus  abdominis  ; 
and  (5)  the  back  of  the  inferior  angle  of  the  scapula,  the  last  origin 
being  inconstant. 

Insertion. — The  floor  of  the  bicipital  groove  of  the  humerus  about 
its  middle  third  for  about  i^  inches. 

Nerve-supply. — The  middle  or  long  subscapular  nerve  from  the 
posterior  cord  of  the  brachial  plexus,  its  fibres  being  derived  chiefly 
from  the  seventh  cervical  nerve.  The  nerve  is  only  seen  during 
the  dissection  of  the  axillary  space,  and  it  enters  the  muscle  on 
its  deep  aspect. 

Blood-supply. — Branches  of  the  subscapular  artery. 

The  upper  fibres  of  the  muscle  pass  horizontally  outwards,  and 
cross  the  inferior  angle  of  the  scapula,  which  they  bind  to  the  chest 
wall ;  the  succeeding  fibres  pass  obliquely  upwards  and  outwards  ; 
and  those  from  the  iliac  crest  and  lower  ribs  pass  almost  vertically 
upwards. 

Action. — The  arm  being  raised,  the  muscle  draws  it  downwards 
and  backwards,  producing  at  the  same  time  internal  rotation,  as 
when  the  hands  are  crossed  behind  the  back.  When  the  muscle 
acts  from  its  insertion,  it  raises  the  pelvis  and  trunk  after  the  out- 
stretched arms,  as  in  the  act  of  climbing  a  pole.  It  also  elevates 
the  last  three  or  four  ribs,  as  in  forced  inspiration. 

At  the  inferior  angle  of  the  scapula  the  muscle  is  behind  the 
teres  major  ;  it  then  winds  round  the  lower  border  of  that  muscle ; 
and  eventually  it  is  placed  in  front  of  it.  The  lower  borders  of 
the  tendons  of  these  muscles  near  their  insertions  are  closely  con- 
nected, but  ultimately  they  become  separated,  a  synovial  bursa 
intervening  between  the  two.  Between  the  upper  border  of  the 
latissimus  dorsi,  the  lower  border  of  the  trapezius,  and  the  base  of 
the  scapula,  there  is  a  triangular  area  in  which  are  exposed  a  portion 
of  the  rhomboideus  major,  the  sixth  rib,  and  the  sixth  intercostal 
s|xice. 

Triangle  of  Petit.— The  anterior  border  of  the  latissimus  dorsi, 
between  the  iliac  crest  and  last  rib,  may  or  may  not  overlap  the 


268  A   MANUAL  OF  ANATOMY 

posterior  border  of  the  obliquus  externus  abdominis.  If  it  does  not 
do  so,  a  small  space  is  left,  called  the  triangle  of  Petit,  which  is  situ- 
ated immediately  above  the  centre  of  the  iliac  crest.  It  is  bounded 
in  front  by  the  posterior  border  of  the  obliquus  externus  abdominis, 
behind  by  the  anterior  border  of  the  latissimus  dorsi,  and  below  by 
the  iliac  crest  near  the  centre.  It  is  covered  only  by  skin  and 
fascia,  and  its  floor  is  formed  by  a  part  of  the  obliquus  internus 
abdominis.  In  this  situation  a  lumbar  hernia  may  occur,  or  a 
lumbar  abscess  may  find  its  way  to  the  surface. 

Levator  Anguli  Scapulae — Origin. — By  four  tendinous  slips  from 
the  posterior  tubercles  of  the  transverse  processes  of  the  first  four 
cervical  vertebrae. 

Insertion. — ^The  base  of  the  scapula  from  the  superior  angle  to  the 
triangular  surface  at  the  root  of  the  spine. 

Nerve- supply. — Branches  of  the  cervical  plexus,  which  are  derived 
from  the  third  and  fourth  cervical  nerves,  and  a  branch  from  the 
nerve  to  the  rhomboids. 

The  muscle  is  directed  downwards,  backwards,  and  slightly 
outwards. 

Action. — Acting  from  its  origin  the  muscle  elevates  the  superior 
angle  of  the  scapula,  thereby  rotating  the  bone  and  causing  the  point 
of  the  shoulder  to  be  depressed.  Acting  from  its  insertion  it  is  a 
lateral  flexor  of  the  neck. 

Rhomboideus  Minor — Origin. — ^The  lower  part  of  the  ligamentum 
nuchfe,  and  the  spines  and  supraspinous  ligament  of  the  seventh 
cervical  and  first  thoracic  vertebrae. 

Insertion. — The  base  of  the  scapula  opposite  the  triangular 
surface  at  the  root  of  the  spine. 

Rhomboideus  Major — Origin. — The  spines  and  supraspinous  liga- 
ments of  thoracic  vertebrae  from  the  second  to  the  fifth  inclusive. 

Insertion. — ^The  base  of  the  scapula  from  the  triangular  surface 
at  the  root  of  the  spine  to  the  inferior  angle.  The  insertion  takes 
place  by  means  of  a  tendinous  expansion,  which  is  firmly  attached 
near  the  inferior  angle.  Elsewhere  the  expansion  is  connected 
with  the  base  of  the  bone  by  connective  tissue,  so  that  the  muscle 
can  be  detached  to  a  large  extent  without  injury. 

Nerve- supply  of  the  Rhomboids. — ^The  nerve  to  the  rhomboids, 
which  is  a  branch  of  the  fifth  cervical.  This  nerve,  having  pierced 
the  scalenus  medius,  gives  a  branch  to  the  levator  anguli  scapulae, 
and  passes  beneath  the  upper  border  of  the  rhomboideus  minor 
about  I  inch  from  the  base  of  the  scapula.  Having  given  a  branch 
to  the  deep  surface  of  that  muscle,  it  passes  beneath  the  rhomboideus 
major  and  enters  its  upper  part. 

The  direction  of  the  rhomboid  muscles  is  downwards  and 
outwards. 

Action. — ^The  muscles  draw  the  scapula  backwards  and  upwards, 
and  rotate  the  bone  so  as  to  depress  the  point  of  the  shoulder. 

Posterior  Scapular  Artery. — ^This  vessel  is  usually  a  branch  of  the 
transverse  cervical,  but  it  may  arise  from  the  third  part  of  the  sub- 


THE   UPPER  LIMB  269 

clavian.  It  passes  backwards  beneath  the  levator  anguh  scapulae, 
and  then  downwards  beneath  the  rhomboid  muscles,  lying  close  to 
the  base  of  the  scapula.  It  gives  off  branches  to  the  adjacent 
muscles,  and  several  offsets  to  the  front  and  back  of  the  scapula, 
which  latter  take  part  in  the  scapular  anastomoses  of  arteries. 

At  the  upper  border  of  the  scapula  a  limited  view  is  obtained  of 
the  posterior  belly  of  the  omo-hyoid  muscle,  and  the  suprascapular 
artery  and  nerve.  The  former  arises  from  the  upper  border  of  the 
bone  inside  the  suprascapular  notch,  as  well  as  from  the  supra- 
scapular or  transverse  ligament.  The  suprascapular  artery  passes 
to  the  supraspinous  fossa  over  the  ligament,  and  the  suprascapular 
nerve  to  the  same  region  beneath  it.  The  artery  in  this  part  of  its 
course  furnishes  its  supra-acromial  branch  to  the  upper  surface  of  the 
acromion  process.  The  transverse  cervical  artery  is  seen,  at  a  higher 
level  than  the  suprascapular,  dividing  into  its  superficial  cervical  and 
posterior  scapular  branches.  The  former  passes  superficial  to  the 
levator  anguli  scapulae,  and  the  latter  beneath  that  muscle. 

It  will  now  be  convenient  to  continue  the  description  of  the 
back  to  its  termination,  except  the  structures  more  immediately 
involved  in  the  head  and  neck. 

Serratus  Posticus  Superior— Ortgm.— The  lower  part  of  the  liga- 
mentum  nuchse,  and  the  spines  and  supraspinous  ligaments  of  the 
last  cervical  and  first  two  thoracic  vertebrae. 

Insertion.— Qy  fleshy  and  tendinous  slips  into  the  upper  borders 
and  outer  surfaces  of  the  second,  third,  fourth,  and  fifth  ribs,  external 
to  their  angles. 

Nerve- supply. —The  second,  third,  and  fourth  intercostal  nerves. 

The  origin  of  the  muscle  is  aponeurotic,  and  continues  so  over 
about  half  its  length.  The  direction  of  the  fibres  is  downwards 
and  outwards. 

Action.— The  muscle  elevates  the  ribs  into  which  it  is  inserted, 
and  is  therefore  a  muscle  of  inspiration. 

Serratus  Posticus  Inferior— Ongm.— The  posterior  lamina  of  the 
lumbar  aponeurosis,  through  means  of  which  the  muscle  is  attached 
to  the  spines  and  supraspinous  ligaments  of  the  lower  two  thoracic 
and  upper  two  or  three  lumbar  vertebrae,  under  cover  of  the 
latissimus  dorsi. 

Insertion.— By  four  fleshy  slips  into  the  lower  borders  of  the  last 

four  ribs. 

Nerve-supply.— T\\e  ninth,  tenth,  and  eleventh  intercostal  nerves. 

The  serrations  of  insertion  overlap  each  other  from  above  down- 
wards ;  the  second  is  the  broadest,  and  the  third  to  a  large  extent 
conceals  the  fourth.  The  direction  of  the  fibres  is  upwards  and 
outwards. 

Action.— {1)  To  draw  backwards  and  slightly  depress  the  lower 
four  ribs,  the  effect  of  which  is  to  increase  the  capacity  of  the 
lower  part  of  the  thoracic  cavity:  and  (2)  to  steady  the  lower  four 
ribs,  and  thus  to  act  as  an  auxiliary  to  the  diaphragm.  In  both 
cases  it  acts  as  a  muscle  of  inspiration. 


270  A   MANUAL  OF  ANATOMY 

Posterior  Lamina  of  the  Lumbar  Aponeurosis. — The  lumbar 
aponeurosis  is  the  posterior  aponeurosis  of  the  transversaHs  ab- 
dominis muscle,  and  is  composed  of  three  laminae — anterior,  middle, 
and  posterior,  the  latter  of  which  is  alone  fully  exposed  in  this 
region.  It  is  of  considerable  strength,  and  is  attached  to  the  spines 
of  the  lumbar  and  sacral  vertebrae,  and  the  posterior  fourth  of  the 
outer  lip  of  the  iliac  crest.  It  affords  origin  to  a  portion  of  the  latis- 
simus  dorsi  and  to  the  serratus  posticus  inferior,  and  lies  behind  the 
erector  spinae,  where  it  forms  the  posterior  wall  of  its  sheath.  At 
the  outer  border  of  that  muscle  it  blends  with  the  middle  lamina, 
which  may  be  partially  seen  by  raising  the  border.  Superiorly  it 
is  joined  by  the  vertebral  aponeurosis. 


Erector  Spim; 


Tranb\erse  Process 

Posterior  Lamina  of  Lumbar  Aponeurosis 


IMiddle  Lamina  of  Lumbar  Aponeurosis 
Quadratus  Lumborum 


Anterior  Lamina  of  Lumbar 
Aponeurosis 
Latissimus  Dorsi 


Body  of  3rd 
Lumbar  Vertebra 


Psoas  Magnus,  covered 
by  Psoas  Fascia 


Obliquus  Ext.  Abd. 
;       Obliquus  Int.  Abdominis 
Transversalis  Abdominis 


Fig.  164.— Diagram  of  the  Lumbar  Aponeurosis. 

Vertebral  Aponeurosis.— This  is  a  thin  aponeurotic  sheet  which 
covers  the  erector  spiuce.  Its  fibres  are  chiefly  arranged  trans- 
versely, being  attached  internally  to  the  spines  of  the  vertebra,  and 
externally  to  the  angles  of  the  ribs.  Superadded  to  the  transverse 
fibres  there  are  a  few  which  are  longitudinal.  Superiorly  the 
aponeurosis  passes  beneath  the  serratus  posticus  superior,  and 
becomes  continuous  with  the  deep  cervical  fascia  as  that  ensheathes 
the  splenius.  Interiorly  it  blends  with  the  posterior  lamina  of  the 
lumbar  aponeurosis.  .  .    , 

Splenius.— This  muscle  is  so  named  because  it  straps  or  binds 
down  the  muscles  beneath  it.  It  is  single  at  its  origin,  but  at  its 
insertion  it  is  divided  into  two  parts— splenius  capitis  and  splenius 
colli. 


THE   UPPER  LIMB  271 

Origin. — (i)  The  lower  two- thirds  of  the  ligamentum  nuchae,  and 
(2)  the  spines  of  the  last  cervical  and  first  six  thoracic  vertebrae. 

Insertion — {a)  Splenius  Capitis. — (i)  The  lower  part  of  the  outer 
surface  of  the  mastoid  process  of  the  temporal  bone,  and  (2)  the 
occipital  bone  below  the  outer  third  of  the  superior  curved  line,  in 
each  case  under  cover  of  the  sterno-cleido-mastoid.  [b)  Splenius 
Colli. — ^The  posterior  tubercles  of  the  transverse  processes  of  the 
first  two  or  three  cervical  vertebrae,  internal  to  the  levator  anguli 
scapulae,  and  in  line  with  the  cervicalis  ascendens. 

Nerve-supply. — The  posterior  primary  divisions  of  the  cervical 
nerves  below  the  third,  and  of  the  upper  five  thoracic. 

The  direction  of  the  fibres  is  upwards  and  outwards. 

Action. — The  muscle  extends  the  head  and  flexes  the  neck  to  its 
own  side,  the  face  being  turned  to  the  same  side. 

Erector  Spinse. — This  composite  muscle  is  single  below  in  the 
region  between  the  last  rib  and  iliac  crest,  where  it  is  strongly 
tendinous  internally,  and  fleshy  externally.  It  subsequently,  how- 
ever, resolves  itself  into  three  columns — outer,  middle,  and  inner, 
there  being  three  muscles  in  each  of  the  outer  and  middle  columns, 
and  one  in  the  inner  column,  thus  making  seven  muscles  in  all. 

Origin. — (i)  The  spines  of  the  last  two  thoracic,  all  the  lumbar, 
and  the  upper  four  sacral  vertebrae  ;  (2)  the  back  of  the  fourth 
sacral  vertebra  ;  (3)  the  posterior  sacro-iliac  ligament ;  and  (4)  the 
posterior  fifth  of  the  iliac  crest.  The  insertion  of  the  muscle  is 
represented  by  the  columns  into  which  it  divides.  On  approaching 
the  last  rib  it  presents  a  groove  on  its  surface,  which  indicates  its 
division  at  this  stage  into  an  outer  and  inner  column,  the  latter 
representing  the  combined  middle  and  inner  columns. 

Outer  Column. — This  column  is  composed  of  three  muscles,  which, 
from  below  upwards,  are  named  ilio-costalis,  musculus  accessorius 
ad  ilio-costalem,  and  cervicalis  ascendens. 

Ilio-costalis. — This  is  the  direct  continuation  of  the  outer  part 
of  the  erector  spinas,  and  it  is  inserted  by  fleshy  and  tendinous 
bundles  into  the  angles  of  ribs  from  the  seventh  to  the  eleventh, 
and  into  the  lower  border  of  the  twelfth  rib. 

Musculus  Accessorius  ad  Ilio-costalem. — This  muscle  prolongs 
the  ilio-costalis  from  the  lower  six  to  the  upper  six  ribs.  It  arises 
by  tendons,  internal  to  the  slips  of  insertion  of  the  ilio-costalis, 
from  the  angles  of  ribs  from  the  seventh  to  the  eleventh,  and  from 
the  outer  surface  of  the  twelfth  rib,  and  it  is  inserted  by  tendons 
into  the  angles  of  the  upper  ribs  from  the  second  to  the  sixth,  and 
into  the  outer  border  of  the  first  rib  external  to  the  tubercle. 

Cervicalis  Ascendens. — This  continues  the  musculus  accessorius 
trom  the  upjjcr  ribs  to  the  neck.  It  arises  by  tendinous  slips  from 
the  third,  fourth,  fifth,  and  sixth  ribs,  internal  to  the  tendons  of 
insertion  of  the  musculus  accessorius,  and  it  is  inserted  into  the 
jjosterior  tubercles  of  the  transverse  processes  of  the  fourth, 
fifth,  and  sixth  cervical  vertebrte,  where  it  is  in  line  with  the 
splenius  colli. 


2/2 


A   MANUAL  OF  ANATOMY 


Action. — The  muscles  of  the  outer  column  act  as  extensors  and 
lateral  flexors  of  the  vertebral  column,  and  as  depressors  of  the 
ribs,  as  in  expiration. 

Middle  Column. — ^This  column,  like  the  outer,  is  composed  of 
three  muscles,  which,  from  below  upwards,  are  named  longissimus 


Complexus 


Cervicaiis  Ascend^ 


Musculus  Accessorius— 


Longissimus  Dorsi--U5Ji- 


Ilio-costalis ^ 


Splenius 


Serratus  Posticus  Superior 


.Vertebral  Aponeu- 
rosis 


.Serratus  Posticus 
Inferior 


Fig.   165. — The  Deep  Muscles  of  the  Back. 


dorsi,   longissimus   cervicis    (transversalis   cervicis),    and   trachelo- 
mastoid  (longissimus  capitis). 

Longissimus  Dorsi. — -This  is  the  direct  continuation  of  the  nner 
part  of  the  erector  spinae,  and  it  is  inserted  in  a  twofold  manner. 
The  inner  insertions  take  the  form  of  round,  tapering  tendons,  which 
are  attached  to  the  accessory  processes  of  the  lumbar  vertebrae  and 
the  extremities  of  the  transverse  processes  of  the  thoracic  vertebrae. 


THE  UPPER  LIMB  273 

The  outer  insertions  are  fleshy,  and  are  attached  to  the  backs  of  the 
transverse  processes  of  the  lumbar  vertebrae,  and  the  outer  surfaces 
of  the  lower  ten  ribs  external  to  the  tubercles. 

Transversalis  Cervicis  (longissimus  cervicis). — ^This  continues  the 
longissimus  dorsi  to  the  neck.  It  arises  from  the  transverse  pro- 
cesses of  the  upper  five  or  six  thoracic  vertebrae,  and  is  inserted 
into  the  posterior  tubercles  of  the  transverse  processes  of  cervical 
vertebrae  from  the  second  to  the  sixth  inclusive,  where  it  is  internal 
to  the  splenius  colli  and  cervicalis  ascendens. 

Trachelo-mastoid  (longissimus  capitis). — ^This  muscle  has  been  so 
named  because  it  extends  from  the  neck  to  the  mastoid  process, 
and  it  continues  the  longissimus  dorsi  to  the  head.  It  arises 
from  the  transverse  processes  of  the  upper  five  or  six  thoracic 
vertebrae  in  close  connection  with  the  longissimus  cervicis,  and 
from  the  articular  processes  and  capsular  ligaments  of  the  lower 
three  cervical  vertebrae.  Its  insertion  is  into  the  lower  part  of  the 
outer  surface  of  the  mastoid  process  under  cover  of  the  splenius 
capitis.  Towards  its  insertion  this  muscle  is  very  narrow  and 
ribbon-like,  and  it  is  marked  by  a  tendinous  intersection. 

Action. — The  muscles  of  the  middle  column  act  as  extensors  and 
lateral  flexors  of  the  vertebral  column.  They  also  extend  the  head 
and  flex  the  neck  to  one  side,  the  face  being  turned  to  the  same  side. 

Inner  Column. — This  consists  of  the  spinalis  dorsi,  which  is 
intimately  associated  with  the  inner  part  of  the  longissimus  dorsi. 
It  arises  from  the  lower  two  thoracic  and  upper  two  lumbar  spines, 
and  it  is  inserted  by  tendinous  slips  into  the  upper  thoracic  spines 
■ — sometimes  the  upper  four,  sometimes  as  many  as  the  upper  eight. 

Action.— This  muscle  is  an  extensor  of  the  thoracic  portion  of 
the  vertebral  column. 

Nerve- supply. — ^The  erector  spinae  and  its  component  muscles 
are  supplied  by  the  posterior  primary  divisions  of  the  spinal  nerves. 

Between  the  iliac  crest  and  the  last  rib  the  erector  spinae  is  enclosed 
in  a  sheath,  the  posterior  wall  of  which  is  formed  by  the  posterior 
lamina  of  the  lumbar  aponeurosis,  affording  origin  to  the  latissimus 
dorsi  and  serratus  posticus  inferior,  whilst  the  anterior  wall  is 
formed  by  the  middle  lamina  of  that  aponeurosis.  On  the  back 
of  the  sacrum  its  tendon  gives  origin  deeply  to  fibres  of  the  multifidus 
spins,  whilst  superficially,  between  the  sacrum  and  the  iliac  crest, 
a  few  fibres  of  the  gluteus  maximus  arise  from  it. 

Complexus — Origin. — (i)  The  extremities  of  the  transverse  pro- 
cesses of  the  upper  six  thoracic  and  last  cervical  vertebrae  ;  and 
(2)  the  backs  of  the  articular  processes  and  capsular  ligaments  of 
three  or  four  cervical  vertebrae  above  the  seventh.  The  muscle 
may  receive  a  fleshy  slip  from  the  spine  of  the  seventh  cervical. 

Insertion. — The  occipital  bone  between  the  superior  and  inferior 
curved  lines,  commencing  at  the  crest  and  extending  outwards  for 
about  2  inches.  The  inner  fibres  of  the  muscle  are  interrupted  about 
the  level  of  the  sixth  cervical  vertebra  by  an  elongated  tendinous 
intersection,  having  the  appearance  of  a  tendon,  with  a  fleshy  belly 


274 


A  MANUAL  OF  ANATOMY 


at  either  extremity,  from  which  circumstance  this  part  is  known 
as  the  biventer  cervicis.  About  the  level  of  the  axis  the  muscle 
usually  presents  another  faint  transverse  intersection. 

Nerve-supply. — (i)  The  posterior  primary  division  of  the  first 
cervical  or  suboccipital  nerve  ;  (2)  the  great  occipital ;  and  (3)  the 
posterior  primary  divisions  of  cervical  nerves  below  the  second. 

The  innermost  and  longest  fibres  pass  almost  vertically  upwards, 


Trachelo-mastoid 


Trachelo-raastoid 

Transversalis  Cervicis 

Semispinalis  Coll 


Semispinalis  Dorsi  _. 


Longissimus  Dorsi 
(turned  outwards) 


Fig.  166. — The  Middle  Column  of  the  Erector  Spin^,  and  the 
Semispinales  Muscles. 

whilst  the  outer  and  upper  fibres,  which  are  short,  pass  upwards 
and  inwards. 

Action. — ^To  extend  the  head  and  incline  it  to  one  side,  the  face 
being  turned  to  the  opposite  side. 

A  small  part  of  the  complexus  may  appear  superficially  in  the 
upper  part  of  the  posterior  triangle  of  the  neck,  this  portion  being 
pierced  by  the  great  occipital  nerve.  As  high  as  the  axis  spine  the 
muscle  rests  upon  the  semispinalis  colh,  and  in  this  situation  an 
arterial  anastomosis  takes  place  between  the  deep  cervical  of  the 
superior  intercostal  from  the  second  part  of  the  subclavian  and  the 


THE  UPPER  LIMB  27; 

deep  branch  of  the  ramus  cervicalis  princeps  of  the  occipital  from 
the  external  carotid.  Above  the  level  of  the  axis  spine  it  covers 
the  recti  capitis  postici  and  obliqui  capitis  muscles,  and  forms  the 
roof  of  the  suboccipital  triangle. 

Semispinalis  Dorsi — Origin. — The  extremities  of  the  transverse 
processes  of  thoracic  vertebrae  from  the  sixth  to  the  tenth  inclusive. 

Insertion. — The  spines  of  the  last  two  cervical  and  upper  four 
thoracic  vertebrae. 

Semispinalis  Colli — Origin. — The  extremities  of  the  transverse 
processes  of  the  upper  five  thoracic  vertebrae. 

Insertion. — The  spines  of  cervical  vertebrae  from  the  second  to 
the  fifth  inclusive. 

The  bundle  of  fibres  inserted  into  the  axis  spine  is  the  largest, 
and  the  bundles  overlap  one  another  from  above  downwards. 

Nerve-supply  of  the  Semispinales. — The  posterior  primary  divisions 
of  the  cervical  and  upper  thoracic  nerves. 

The  fibres  of  the  two  muscles  are  directed  upwards  and  inwards. 

Action. — The  muscles  are  extensors  and  lateral  flexors  of  the 
vertebral  column.  The  semispinalis  colli  and  the  cervical  portion 
of  the  semispinalis  dorsi  also  rotate  the  cervical  vertebra;  towards 
the  opposite  side. 

Multifidus  Spinas. — This  muscle  lies  deeply  in  the  groove  by  the 
sides  of  the  spines  of  the  vertebrae. 

Origin.— {1)  The  sacral  groove,  and  the  deep  surface  of  the  tendon 
of  the  erector  spinae ;  (2)  the  posterior  sacro-ihac  ligament,  and  the 
inner  hp  of  the  iliac  crest  at  its  back  part  ;  (3)  the  mammillary 
tubercles  of  the  lumbar  vertebra?  ;  (4)  the  transverse  processes  of 
the  thoracic  vertebrae  ;  and  (5)  the  articular  processes  of  the  lower 
four  cervical  vertebrae. 

Insertion. — The  spines  of  the  vertebrae  from  root  to  tip. 

The  superficial  fibres  from  any  given  origin  pass  over  three  or  four 
vertebra;  before  taking  insertion,  the  succeeding  fibres  pass  over 
two  or  three,  and  the  deeper  fibres  pass  over  one. 

Nerve-supply. — The  posterior  primary  divisions  of  the  spinal  nerves. 

A  ction.—The  muscle  is  an  extensor  and  lateral  flexor  of  the  spinal 
column,  producing  at  the  same  time  rotation  towards  the  opposite 
side  in  the  cervical  and  thoracic  regions. 

Rotatores  Spinae. — These  muscles  are  really  the  deepest  fibres  of 
the  multifidus  spina;  in  the  thoracic  region.  They  are  eleven  in 
number. 

Origin.— The  upper  and  back  part  of  a  transverse  process. 

Insertion. — The  lower  border  of  the  lamina  of  the  vertebra  imme- 
diately above. 

Nerve-supply. — The  posterior  primary  divisions  of  the  spinal  nerves. 

.4dion. —To  rotate  the  vertebra  towards  the  opposite  side. 

Interspinales. — These  muscles  are  usually  confined  to  the  cervical 
and  lumbar  regions,  where  they  are  arranged  in  |)airs  between  the 
spines,  one  on  either  side  of  the  middle  line.  In  the  neck  they 
are  limited  to  the  region  of  the  apices  of  the  spines,  but  in  the 

18—2 


276 


A   MANUAL  OF  ANATOMY 


lumbar  region  they  extend  very  nearly  over  their  whole  length.  In 
the  neck  the  muscles  of  each  pair  are  separated  by  a  deep  process 
of  the  ligamentum  nuchae,  representing  an  interspinous  ligament, 
and  in  the  lumbar  region  they  are  separated  by  the  interspinous 
ligaments  themselves. 


^[ultitidus  Spinee 


Levator  Costse 


.  Rotator  Spinffi 


Levator  Costse  Longior 


Fig.  167. — The  Multifidus  Spin^  and  Levatores  Costarum 
Muscles. 


Nerve-supply. — Posterior  primary  divisions  of  spinal  nerves. 

Action. — ^To  extend  the  vertebrae. 

Intertransversales. — These  muscles  occur  chiefly  in  the  cervical 
and  lumbar  regions,  where  they  are  arranged  in  pairs  in  each  space. 
In  the  neck  they  extend  between  the  anterior  and  posterior  tubercles 
of  adjacent  vertebrae.  In  the  lumbar  region  the  muscles  of  each 
pair  are  arranged  as  lateral  and  mesial.  The  intertransversales 
laterales  extend  between  two  given  transverse  processes,  and  the 


THE   UPPER  LIMB  277 

intertransversales  mediales  extend  from  the  accessory  process  of 
one  vertebra  to  the  mammillar-v  process  of  the  vertebra  below. 
Sometimes  intertransversales  muscles  are  met  with  in  the  lower 
thoracic  region. 

Nerve-supply. — Posterior  primary  divisions  of  spinal  nerves. 

Action. — ^The  muscles  act  as  lateral  flexors  of  the  vertebral 
column. 

Levatores  Costarum. — These  are  twelve  in  number  on  either 
side. 

Origin. — The  highest  muscle  arises  from  the  tip  of  the  transverse 
process  of  the  seventh  cervical  vertebra,  and  the  succeeding  eleven 
arise  from  the  tips  of  the  transverse  processes  of  the  thoracic  verte- 
brae from  the  first  to  the  eleventh  inclusive. 

Insertion. — Each  muscle  is  inserted  into  the  outer  surface  of  the 
rib  below,  from  the  tubercle  to  the  angle.  In  the  case  of  the  lower 
two  or  three  muscles  the  more  superficial  fibres  pass  over  the  first 
rib  below  and  take  insertion  into  the  next  rib,  these  fibres  con- 
stituting the  levatores  costarum  longiores. 

Nerve-supply. — The  intercostal  nerves. 

The  muscles  are  directed  downwards  and  outwards. 

Action. — ^To  elevate  the  ribs,  as  in  inspiration. 

Each  muscle  is  somewhat  fan-shaped,  and  contains  an  admixture 
of  aponeurotic  fibres.  In  direction  the  muscles  coincide  with  the 
external  intercostals,  with  which  they  are  closely  incorporated 
by  their  outer  borders.  They  are  covered  by  the  erector  spinae, 
and  by  their  deep  surfaces  they  are  related  to  the  external  inter- 
costals. 

Posterior  Primary  Divisions  of  Spinal  Nerves. — These  nerves  in 
the  thoracic  region  pass  backwards,  each  through  a  four-sided  space 
bounded  below  by  the  neck  of  a  rib,  above  by  the  transverse  process 
of  the  upper  vertebra,  externally  by  the  superior  costo-ti-ansverse 
ligament,  and  internally  by  the  body  of  a  vertebra.  Between  the 
transverse  processes  each  divides  into  an  internal  and  external 
branch.  The  internal  branches  incline  inwards  on  the  superficial 
surface  of  the  multifidus  spins,  and  the  upper  six  become  cutaneous 
near  the  spines  of  the  vertebrae,  whilst  the  lower  six  end  in  the 
deep  muscles.  The  external  branches  pass  outwards  beneath  the 
middle  column  of  the  erector  spin^e,  and,  on  reaching  the  interval 
between  the  middle  and  outer  columns  of  that  muscle,  they  end 
differently  in  the  upper  and  lower  parts  of  the  back.  The  upper 
six  end  in  the  deep  muscles,  but  the  lower  six  become  cutaneous 
along  the  line  of  the  angles  of  the  ribs.  In  the  lumbar  region  the 
posterior  primary  divisions  pass  backwards,  each  through  a  space 
bounded  externally  by  the  quadratus  lumborum  muscle,  internally 
by  the  intertransversalis  lateralis  muscle,  and  above  and  below  by 
a  transverse  process.  Their  further  disposition  is  as  in  the  thoracic 
region,  but  the  external  branches  of  the  first  three  only  furnish 
cutaneous  nerves,  and,  as  already  stated,  these  are  jMincipally 
gluteal  in  their  distribution. 


278  A  MANUAL  OF  ANATOMY 

The  arteries  of  the  thoracic  region  are  the  dorsal  branches  of  the 
intercostal  arteries.  Each  dorsal  branch  passes  backwards  in  com- 
pany with  the  corresponding  posterior  primary  division  of  a  spinal 
nerve.  Before  passing  through  the  quadrangular  space  it  gives  off 
a  spinal  branch,  which  enters  the  spinal  canal  through  the  inter- 
vertebral foramen.  After  passing  backwards  it  divides  into  an 
internal  and  external  branch,  which  have  a  distribution  similar  to 
those  of  the  nerve. 

The  veins  of  the  thoracic  region  terminate  in  the  intercostal  veins. 

The  arteries  of  the  lumbar  region  are  the  dorsal  branches  of  the 
lumbar  arteries.  Each  accompanies  the  corresponding  posterior 
primary  division  of  a  spinal  nerve,  and  its  distribution  is  as  in  the 
thoracic  region. 

The  veins  of  the  lumbar  region  terminate  in  the  inferior  vena 
cava. 


THE  PECTORAL  REGION  AND  AXILLARY  SPACE. 

Landmarks. — The  outline  of  the  clavicle  and  acromion  process 
of  the  scapula  are  readily  made  out,  and,  in  connection  with  the 
acromion,  it  is  to  be  borne  in  mind  that  the  acromial  epiphysis  may 
remain  permanently  detached  from  the  spine,  and  so  simulate  a 
fracture.  The  roundness  of  the  shoulder  is  to  be  noted,  this  being 
due  largely  to  the  deltoid  muscle,  but  also  in  part  to  the  head  of  the 
humerus.  Below  the  clavicle,  at  a  point  external  to  its  centre,  is  a 
depression,  called  the  infraclavicular  fossa,  which  indicates  the 
separation  between  the  deltoid  and  pectoralis  major.  When  the 
arm  is  abducted  and  the  finger  pressed  into  this  hollow,  the  inner 
border  of  the  coracoid  process  will  be  felt,  and,  if  the  finger  be  carried 
outwards  under  the  deltoid,  the  tip  of  that  process  can  be  made  out. 
In  this  region  it  is  possible  to  compress  the  axillary  artery  against 
the  second  rib,  but  this  requires  deep  pressure.  The  course  of  this 
artery  may  be  indicated  by  a  line  drawn  from  the  centre  of  the 
clavicle  to  the  inner  border  of  the  coraco-brachialis,  the  arm  having 
been  raised  to  a  right  angle  with  the  trunk,  so  as  to  define  clearly 
the  outline  of  that  muscle.  The  anterior  and  posterior  folds  of  the 
axilla  are  to  be  observed,  the  anterior  being  formed  by  the  lower 
border  of  the  pectoralis  major,  which  practically  coincides  with  the 
line  of  the  fifth  rib,  and  the  posterior  by  the  latissimus  dorsi  winding 
round  the  lower  border  of  the  teres  major.  The  hollow  between 
these  folds  indicates  the  position  of  the  axillary  space,  and  it  will  be 
seen  to  be  narrow  towards  the  arm,  but  wide  towards  the  thoracic 
wall.  In  the  female  the  prominence  formed  by  the  mammary  gland 
is  usually  apparent  on  the  surface  of  the  pectoralis  major.  Its 
vertical  extent  is  from  the  second  to  the  sixth  rib,  and  it  reaches 
transversely  from  the  side  of  the  sternum  to  the  anterior  fold  of  the 
axilla,  except  at  the  lower  and  outer  part,  where  it  extends  beyond 
this  fold  upon  the  serratus  magnus.  A  little  below  and  internal  to 
the  centre  of  the  mammary  prominence  is  the  nipple,  which  is  sur- 


THE   UPPER  LIMB  279 

rounded  by  a  coloured  circle,  called  the  areola.  The  exact  position 
of  the  nipple  is  subject  to  variation.  As  a  rule  it  may  be  said  to 
lie  over  the  fourth  intercostal  space  about  4  inches  from  the  mid- 
sternal  line,  but  in  corpulent  persons,  and  in  females  with  pendulous 
mammffi,  it  is  lower  in  position.  Along  the  middle  line  the  sternum 
can  readily  be  made  out.  and  about  2  inches  below  its  upper  border 
the  transverse  ridge,  called  the  sternal  angle,  may  be  felt,  which  is 
the  guide  to  the  second  costal  cartilage  at  either  side.  Above  the 
centre  of  the  upper  border  of  the  sternum  is  a  depression,  known 
as  the  jugular  fossa.  Below  the  lower  border  of  the  mesosternum 
there  is  the  infrasternal  depression,  which  is  situated  between  the 
seventh  pair  of  costal  cartilages,  where  it  lies  over  the  meta- 
sternum. 

Cutaneous  Nerves. — These  nerves  are  arranged  in  three  groups — 
descending,  anterior,  and  lateral. 

The  descending  nerves  are  branches  of  the  cervical  plexus,  and 
are  derived  from  the  third  and  fourth  cervical  nerves.  They  are 
three  in  number — suprasternal  or  internal,  supraclavicular  or  middle, 
and  supra-acromial  or  external — and,  as  they  descend,  they  lie 
beneath  the  platysma  myoides.  The  suprasternal  nerve  crosses  the 
inner  end  of  the  clavicle,  and  its  branches  are  distributed  to  the  sub- 
jacent integument,  as  well  as  to  that  over  the  upper  part  of  the 
sternum.  The  supraclavicular  nerve  crosses  the  centre  of  the  bone, 
and  its  branches  have  a  fairly  wide  distribution  to  the  pectoral  in- 
tegument. The  supra-acromial  nerve  crosses  the  outer  end  of  the 
clavicle,  and  its  branches  are  distributed  to  the  integument  over  the 
upper  half  of  the  deltoid. 

The  anterior  cutaneous  nerves  are  the  terminal  branches  of  the 
upper  six  intercostal  nerves,  and  they  pierce  the  pectoralis  major 
close  to  the  sternum.  They  furnish  small  twigs  to  the  integument 
over  that  bone,  but  the  principal  part  of  each  nerve  takes  an  out- 
ward course  and  supplies  the  pectoral  integument.  The  branch  of 
the  first  nerve  is  sometimes  absent. 

The  lateral  cutaneous  nerves  are  branches  of  the  intercostal 
nerves  from  the  third  to  the  sixth  inclusive.  The  first  inter- 
costal nerve  gives  no  lateral  cutaneous  branch.  The  lateral 
cutaneous  of  the  second  intercostal  nerve  is  undivided,  and  crosses 
the  axillary  space  to  the  brachial  region,  under  the  name  of  inter- 
costo-humeral.  The  succeeding  lateral  cutaneous  nerves  emerge 
from  their  intercostal  spaces  by  piercing  the  external  intercostal 
muscles  not  far  from  the  lower  border  of  the  pectoralis  major. 
Each  then  divides  into  an  anterior  and  a  posterior  branch,  which 
pass  out  between  the  digitations  of  the  serratus  magnus,  being 
separated  from  each  other  by  a  slight  interval.  The  anterior 
branches  wind  round  the  lower  border  of  the  pectoralis  major  to 
supply  the  pectoral  integument,  whilst  the  posterior  branches  pass 
backwards  to  su])ply  the  integument  over  the  anterior  border  of  the 
latissimus  dorsi. 

The  anterior  and  lateral  cutaneous  nerves  are  accompanied  by 


28o 


A   MANUAL  OF  ANATOMY 


corresponding  arteries,  the  anterior  being  the  perforating  branches 
of  the  internal  mammary,  and  the  lateral  being  branches  of  the 
intercostal  arteries. 

Fascia.- — ^The  superficial  fascia  is  continuous  over  the  clavicle  with 
the  superficial  fascia  of  the  neck,  and  it  is  noteworthy  in  two  respects. 


Hypogastric  Branch, 
of  Ilio-hypogastric 


.  I  ntercosto-humeral 

I-  - .  -Additional  Intercosto- 
humeral 


Lateral  Cutaneous  of 
1 2th  Thoracic 


Iliac  Branch  of  Ilio- 
hypogastric 


Fig.    i68.- 


-CuTANEOus  Nerves  of  the  Trunk  (Antero-lateral 
View)   (after  Henle). 


I -1 2,  Anterior  Cutaneous  ;   2-12,  Lateral  Cutaneous. 

In  the  first  place,  just  below  the  clavicle  it  has  a  faint  reddish 
colour,  due  to  the  fact  that  over  the  clavicular  portions  of  the 
pectoralis  major  and  deltoid  it  gives  origin  to  fibres  of  the  platysma 
myoides,  which  can  be  seen  on  incising  it.  In  the  second  place,  in 
the  region  of  the  mammary  gland  it  divides  into  two  laminae,  which 
ensheathe  that  gland.     These  laminae  send  processes  into  the  sub- 


THE   UPPER  LIMB  281 

Stance  of  the  gland  which  support  its  lobes,  and  from  the  anterior 
lamina  fibrous  bands  pass  to  the  integument,  these  being  known 
as  the  ligamenta  suspensoria  of  Cooper.  Interiorly  the  superficial 
fascia  is  continuous  with  that  over  the  anterior  abdominal  wall, 
and  externally  it  is  prolonged  over  the  floor  of  the  axillary  space 
to  become  continuous  with  the  superficial  fascia  of  the  brachial 
region. 

The  deep  fascia  is  thin  and  membranous,  and  it  closely  invests 
the  pectoralis  major.  Superiorly  it  is  attached  to  the  front  of 
the  clavicle  above  the  origin  of  that  muscle,  internally  it  is  fixed 
to  the  front  of  the  sternum,  externally  it  is  continuous  with  the 
deep  fascia  over  the  deltoid,  and  interiorly  it  joins  the  axillary 
fascia  at  the  lower  border  of  the  pectoralis  major. 

The  axillary  fascia  is  a  firm  membrane  which  stretches  from  the 
anterior  to  the  posterior  fold  of  the  axilla,  and  forms  the  floor  of 
that  space.  It  is  continuous  in  front  with  the  deep  pectoral  fascia, 
and  behind  it  blends  with  the  deep  fascia  which  ensheathes  the 
latissimus  dorsi.  Externally  it  is  continuous  with  the  deep  fascia 
of  the  brachial  region,  and  "internally  with  the  fascia  covering  the 
serratus  magnus.  Its  upper  surface  is  convex,  due  to  the  fact  that 
it  receives,  near  the  pectoralis  major,  the  clavi-pectoral  fascia, 
to  be  afterwards  described.  In  this  way  the  axillary  fascia  is  drawn 
upwards  into  the  space.  It  is  of  considerable  strength,  and  is  capable 
of  affording  much  resistance  to  the  pointing  of  an  axillary  abscess 
in  this  direction. 

Mammary  Gland. — ^This  gland  is  situated  on  the  surface  of  the 
pectoralis  major.  It  is  somewhat  hemispherical,  and  extends 
vertically  from  the  second  to  the  sixth  rib,  and  transversely  from 
the  side'  of  the  sternum  to  the  anterior  fold  of  the  axilla,  except 
below  and  externally,  where  it  passes  over  that  fold  upon  the 
serratus  magnus.  Alittle  below,  and  internal  to,  the  centre  of  the 
gland  is  the  corrugated  nipple,  lying  in  the  centre  of  a  coloured 
circle,  called  the  areola.  There  is  no  fat  beneath  the  nipple  and 
areola,  and  the  skin  of  these  parts  is  provided  with  plain 
muscular  tissue  disposed  circularly,  which,  by  its  contraction, 
contributes  to  erection  of  the  nipple  by  compressing  its  veins. 
The  summit  of  the  nipple  is  perforated  by  the  openings  of  the 
lactiferous  ducts.  The  skin  of  the  areola  presents  a  number 
of  small  projections  due  to  sebaceous  glands,  which  are  known 
as  the  glands  of  Montgomery.  The  mamma  is  a  compound  race- 
mo.se  gland,  which  is  composed  of  about  twenty  lobes,  these  in 
turn  consisting  of  lobules,  and  all  being  connected  by  a  fibrous 
stroma.  The  entire  gland  is  ensheathed  by  the  sp^litting  of  the 
superficial  pectoral  fascia  into  two  laminae,  and  these  send  processes 
into  its  interior  which  supj^ort  its  component  lobes.  The  posterior 
layer  of  the  sheath  is  loosely  connected  to  the  deep  pectoral  fascia 
covering  the  pectoralis  major,  and  sometimes  deep  processes  of  the 
gland  penetrate  into  the  substance  of  the  muscle.  The  lobes  are 
pyramidal,  and  their  apices  converge  toward  the  nipple.     Each  of 


282 


A   MANUAL  OF  ANATOMY 


them  is  distinct,  and  has  its  own  duct.  A  lobe  is  made  up  of  lobuJes, 
and  each  lobule  is  composed  of  a  cluster  of  tubes,  called  alveoli  or 
acini,  which  represent  the  secreting  parts  of  the  gland,  and  are 
lodged  in  spaces  known  as  loculi.  The  alveolar  tubes  are  lined  with 
cubical  epithelium,  the  cehs  of  which  contain  fat  globules  during  the 
period  of  the  functional  activity  of  the  organ.  The  ducts  of  the 
lobes  are  about  twenty  in  number,  and  are  called  the  lactiferous  or 


Areola 


^*i3H^-' 


Fig.    169. — The  Female  Mamma  during  Lactation 
(after  Luschka). 


galactophorous  ducts.  They  are  lined  with  columnar  epithelium, 
and,  as  they  approach  the  nipple,  each  presents  a  dilatation,  called 
the  sinus  or  ampulla.  Thereafter  each  duct  becomes  narrow,  and 
enters  the  nipple  to  terminate  by  a  minute  pore  on  its  summit. 
The  mammary  glands  are  present  in  both  sexes,  but  in  the  male 
their  development,  as  a  rule,  is  arrested,  so  that  they  are  in  a 
rudimentary  condition. 

Bloodvessels  of  the  Mamma. — The  arteries  are  as  follows  : 
long  thoracic  (external  mammary)  of  the  second  part  of  the 
axillary  ;  anterior  cutaneous  or  perforating  of  the  internal  mam- 
mary ;  and  branches  from  the  intercostal  arteries  of  the  spaces 
over  which  the  gland  lies. 

The  veins  pass  to  the  axillary  and  internal  mammary  veins. 

Lymphatics. — The  most  of  the  lymphatics  pass  to  the  pectoral 
group  of  axillary  glands,  but  those  from  the  inner  portion  of  the 
organ  pass  to  the  internal  mammary  glands,  which  lie  along  the 
course  of  the  artery  of  that  name  at  the  side  of  the  sternum. 


THE  UPPER  LIMB  283 

Nerves. — These  are  derived  from  the  supraclavicular  branch  of 
the  cervical  plexus,  and  the  anterior  and  lateral  cutaneous  branches 
of  the  upper  intercostal  nerves. 

Accessory  mammae  are  sometimes  met  with  on  the  upper,  lower, 
and  inner  outskirts  of  the  main  gland,  and  more  rarely  in  the 
axilla,  or  on  the  upper  part  of  the  anterior  abdominal  wall. 

Structure. — The  lactiferous  ducts  are  lined  with  columnar  epithelium, 
except  near  their  orifices,  where  it  is  stratified.  External  to  the  epithelium 
there  is  a  connective-tissue  coat.  The  alveoU  are  hned,  during  the  functional 
activity  of  the  gland,  with  cubical  epithelium,  and  the  basement  membrane 
consists  of  connective-tissue  cells. 

Development  of  the  Mamma.  —  The  mammary  gland  appears  from  the 
fifth  to  the  sixth  week  of  intra-uterine  life  as  an  annular  ridge  of  the  epiblast 
in  the  region  of  the  future  gland.  This  grows  downwards  at  its  centre  into 
the  mesoblast,  which  latter  gives  rise  to  the  fibrous  stroma.  The  cells  of  the 
depressed  portion  of  the  epiblast  grow  into  the  mesoblast  in  the  form  of  solid 
processes,  which,  becoming  hollow,  give  rise  to  the  ducts  of  the  gland,  and  these 
rocesses,  by  their  branching  and  subdivision,  form  the  lobes,  lobules,  and 
a  Iveoli.  Subsequently  the  depressed  area  of  epiblast  becomes  elevated,  and 
gives  rise  to  the  nipple. 

Pectoralis  Major — Origin. — (i)  The  anterior  surface  of  the 
clavicle  over  its  inner  half,  and  the  anterior  sterno-clavicular 
ligament;  (2)  one-half  of  the  anterior  surface  of  the  sternum  as 
low  as  the  metasternum;  (3)  the  anterior  surfaces  of  the  upper 
six  costal  cartilages,  and  slightly  from  the  bony  part  of  the  sixth 
rib;  and  (4)  the  upper  portion  of  the  external  oblique  aponeurosis. 

Insertion. — The  outer  bicipital  ridge  of  the  humerus  over  its 
lower  three-fourths. 

The  muscle  is  divisible  into  two  portions,  clavicular  and  sterno- 
costal, which  are  separated  by  a  slight  interval  extending  down- 
wards and  outwards  from  the  sterno-clavicular  joint. 

The  tendon  of  insertion  is  folded  upon  itself  so  as  to  be  composed 
of  two  layers,  anterior  and  posterior,  the  former  of  which  is  the 
shorter,  and  both  being  continuous  below.  The  anterior  layer 
receives  the  sterno-costal  fibres  above  the  third  costal  cartilage, 
and  it  also  receives  superficially  the  clavicular  fibres,  which  latter 
descend  lowest  at  their  insertion,  where  they  are  intimately  con- 
nected with  the  tendon  of  the  deltoid.  The  posterior  layer  receives 
all  the  fibres  from  the  third  costal  cartilage  downwards,  and  the 
lowest  of  these  fibres,  as  they  pass  outwards  and  upwards,  become 
successively  folded  underneath  the  fibres  above.  The  result  is 
that  the  fibres  arising  lowest  reach  the  highest  part  of  the  posterior 
layer  of  the  tendon,  whilst  the  fibres  above  these  reach  its  lowest 
part.  The  posterior  layer  ascends  higher  on  the  outer  bicipital 
ridge  than  the  anterior,  and  from  its  upper  border  a  tendinous 
expansion  passes  to  the  great  tuberosity  of  the  humerus  and  the 
capsular  ligament  of  the  shoulder-joint,  which  conceals  the  long 
tendon  of  the  biceps  brachii.  From  the  lower  border  of  the  tendon 
an  expansion  is  given  to  the  deep  fascia  of  the  arm. 

Nerve-supply. — (i)  The  external  anterior  thoracic  from  the  outer 
cord  of  the  brachial  plexus,  (its  fibres  coming  from  the  fifth,  sixth, 
and  seventh  cervical  nerves),  the  branches  of  which  nerve  enter 


284 


A   MANUAL  OF  ANATOMY 


the  deep  surface  of  the  clavicular  and  upper  sterno-costal  portions  ; 
and  (2)  the  internal  anterior  thoracic,  the  branches  of  which  enter 
the  deep  surface  of  the  sterno-costal  portion,  after  having  pierced 
the  pectoralis  minor. 

Blood-supply. — Branches  of  the  thoracic  axis. 

The  upper  fibres  pass  downwards  and  outwards,  the  middle 
transversely  outwards,  and  the  lower  upwards  and  outwards. 

Action. — Acting  from  its  origin  the  muscle  adducts  the  arm, 
draws  it  forwards — that  is  to  say,  flexes  it  at  the  shoulder- joint 


Clavicular  part  of  Pectoralis  Major 
Clavicular  part  of  Deltoid 


Coraco-brachialis 


Sterno-costal  part 
of  Pectoralis 
Major 


Latissimus  Dorsi  and 

Teres  Major 

Biceps 

Long  Head  of  Triceps 

Brachialis  Anticus 


Supinator  Radii 
Brevis 
Brachio-radialis 


■^^     Obliquus  Ext.  Abdominis 
Serratus  Magnus 

Internal  Head  of  Triceps 


"~~~--- Brachialis  Anticus 
..Pronator  Radii  Teres 


-  -Flexor  Carpi  Radialis 

-  Palmaris  Longus 
-Flexor  Carpi  Ulnaris 


Fig.  170.— The  Superficial  Muscles  of  the  Front  and  Inner  Side 
OF  THE  Pectoral  and  Brachial  Regions. 

(by  its  clavicular  portion),  and  rotates  it  inwards.  Acting  from 
Its  insertion  it  raises  the  trunk  after  the  outstretched  arm,  as 
m  climbing  a  pole,  and  it  elevates  the  upper  ribs  in  forced 
inspiration. 

The  upper  border  of  the  muscle  is  related  to  the  deltoid,  from 
which  It  is  separated  by  a  triangular  interval  for  a  short  distance 
below  the  clavicle,  and  the  cephalic  vein  and  humeral  artery  inter- 
vene between  the  two.  The  lower  border  forms  the  anterior  fold 
of  the  axilla.     Sometimes  there  is  a  muscle,  called  the  sternalis, 


THE   UPPER  LIMB 


281; 


present,  on  one  or  both  sides.  It  lies  over  the  sternal  fibres  of  the 
pectoralis  major,  and  is  connected  below  with  the  external  oblique 
aponeurosis,  whilst  above  it  may  terminate  in  the  sternal  head 
of  the  sterno-cleido-mastoid,  or  on  the  presternum. 

Clavi-pectoral  Fascia. — This  is  situated  beneath  the  pectoralis 
major.  Superiorly  it  is  disposed  in  two  laminae,  which  are  attached 
to  the  anterior  and  posterior  lips  of  the  subclavian  groove  of  the 
clavicle,  and  embrace  the  subclavius  muscle.  At  the  lower  border 
of  that  muscle  they  unite  to  form  the  costo-coracoid  membrane, 
which,  on  reaching  the  upper  border  of  the  pectoralis  minor, 
divides  to  ensheathe  it.  At  the  lower  border  of  the  muscle  the 
two  layers  unite  to  form  a  single  sheet,  which  joins  the  axillary 
fascia,  and  acts  as  a  suspensory  ligament. 


Section  of  Clavicle 


Axillary  Artery  aiic 
its  Sheath 


-Clavicular  Portion  of 

Pectoralis  Major 

(turned  up) 


Subclavius 

Costo-coracoid  Membrane 

Pectoralis  Minor 

Lower  Portion  of  Clavi- 
pectoral  Fascia 

>^»i^a*-_Lower  Portion  of  Pectoralis 


Axillary  Fascia 


Fig.   171. — Diagram  of  the  Clavi-pectoral  Fascia  and  the 
CosTO-coRACoin  Membrane. 


Costo-coracoid  Membrane. — This  name  is  given  to  that  portion 
of  the  clavi-pectoral  fascia  which  extends  from  the  lower  border  of 
the  subclavius  to  the  upper  border  of  the  pectoralis  minor.  The 
lower  portion  of  the  membrane  is  tense  and  cord-like,  and  is  known 
as  the  costo-coracoid  ligament.  It  is  attached  internally  to  the 
upper  surface  of  the  first  rib  at  its  sternal  extremity  in  connection 
with  the  tendon  of  the  subclavius,  and  externally  it  is  attached  to 
the  posterior  part  of  the  antero-internal  border  and  adjacent  portion 
of  the  upper  surface  of  the  coracoid  j)rocess.  This  membrane  is 
connected  by  its  deej)  surface  with  the  axillary  sheath  ;  it  is  covered 
by  the  clavicular  portion  of  the  ])ectoralis  major  ;  and  it  is  pierced 
by  the  cephalic  vein,  the  thoracic  axis,  and  the  external  anterior 
thoracic  nerve. 


286  A  MANUAL  OF  ANATOMY 

The  costo-coracoid  ligament  represents  the  ventral  end  of  the  coracoid  bar 

of  cartilage,  the  dorsal  end  of  which  forms  the  coracoid  process. 

Pectoralis  Minor — Origin. — The  upper  borders  and  outer  surfaces 
of  the  third,  fourth,  and  fifth  ribs  near  their  anterior  extremities,  as 
well  as  from  the  fascia  covering  the  adjacent  external  intercostal 
muscles. 

Insertion. — The  anterior  half  of  the  antero-internal  border  of  the 
coracoid  process  of  the  scapula  and  the  adjacent  portion  of  its  upper 
surface,  where  it  is  intimately  connected  with  the  common  origin 
of  the  coraco-brachialis  and  short  head  of  the  biceps. 

Nerve-supfly. — The  internal  anterior  thoracic  nerve,  which  is  a 
branch  of  the  inner  cord  of  the  brachial  plexus,  its  fibres  being 
derived  from  the  eighth  cervical  and  first  thoracic.  The  branches  of 
the  nerve  enter  the  muscle  on  its  deep  surface,  and  a  few  of  them 
pierce  it  to  enter  the  deep  surface  of  the  pectoralis  major. 

Blood-supply. — The  thoracic  axis. 

The  direction  of  the  fibres  is  upwards  and  outwards. 

Action. — Acting  from  its  origin  the  muscle  draws  the  scapula 
downwards  and  forwards,  the  point  of  the  shoulder  being  at  the  same 
time  depressed.  Acting  from  its  insertion  it  elevates  the  ribs  from 
which  it  arises,  as  in  forced  inspiration. 

Subclavius — Origin. — By  a  rounded,  tapering  tendon  from  the 
upper  surface  of  the  first  rib  and  its  cartilage. 

Insertion. — The  subclavian  groove  on  the  under  surface  of  the 
clavicle,  extending  from  the  rhomboid  impression  internally  to  the 
interval  between  the  conoid  tubercle  and  trapezoid  ridge  externally. 

Nerve-supply. — The  nerve  to  the  subclavius,  which  arises  from  the 
front  of  the  upper  trunk  of  the  brachial  plexus,  its  fibres  being 
derived  from  the  fifth  cervical.  The  nerve  descends  from  the  neck 
behind  the  clavicle,  and  enters  the  deep  surface  of  the  muscle. 

Blood-supply. — The  thoracic  axis. 

The  direction  of  the  fibres  is  upwards  and  outwards. 

Action. — (i)  To  depress  the  clavicle  and  draw  it  slightly  forwards, 
and  (2)  to  support  the  sterno-clavicular  joint  by  bracing  the  clavicle 
in  an  inward  direction. 

Axillary  Space. — The  axillary  space  is  situated  between  the  upper 
part  of  the  arm  and  upper  part  of  the  thoracic  wall.  It  has  the  form 
of  a  four-sided  p5n:amid,  and  presents  an  apex,  a  base  or  floor,  and 
four  walls — anterior,  posterior,  inner,  and  outer.  It  is  of  much 
greater  extent  towards  the  thoracic  wall  than  towards  the  arm,  on 
account  of  the  convergence  in  the  latter  direction  of  the  structures 
forming  the  anterior  and  posterior  walls.  The  apex  is  the  narrowest 
part  of  the  space,  and  is  directed  upwards  towards  the  root  of  the 
neck.  It  is  somewhat  triangular,  and  lies  between  the  clavicle, 
first  rib,  and  upper  border  of  the  scapula.  The  base  or  floor  is  of 
considerable  extent,  and  is  formed  directly  by  the  axillary  fascia, 
which,  as  stated,  is  drawn  upwards  into  the  space  by  the  clavi- 
pectoral  fascia.  The  anterior  wall  is  formed  over  its  whole  extent 
by  the  pectoralis  major,  and,  under  cover  of  this,  by  the  pectoralis 


THE   UPPER  LIMB 


287 


minor  over  about  its  middle  third.  Above  the  latter  muscle  the 
costo-coracoid  membrane  enters  into  the  anterior  wall.  The  lower 
border  of  the  anterior  wall,  formed  by  the  pectoralis  major,  con- 
stitutes the  anterior  fold  of  the  axilla.  The  posterior  wall  is  formed 
from  above  downwards  by  the  subscapularis,  teres  major,  and  latis- 
simus  dorsi.  Towards  the  arm  the  tendon  of  the  latissimus  dorsi 
lies  in  front  of  the  teres  major,  the  latter  muscle  extending  a  little 
lower  down.  The  posterior  wah  is  longer  than  the  anterior,  and  its 
lower  border,  formed  by  the  folding  of  the  latissimus  dorsi  round  the 
teres  major  to  get  in  front  of  it,  forms  the  posterior  fold  of  the  axilla. 
The  inner  wall  is  formed  by  the  upper  four  or  five  ribs,  with  their 
intercostal  muscles,  and  the  corresponding  serrations  of  the  serratus 


Brachial  Plexus 
Cephalic  Vein 
Musculo-cutaneous  Nerve 
Deltoid  \ 


Trapezius 

'  Suprascapular  Vessels 

/  ',  Transverse  Cervical  Artery 

Posterior  Belly  of  Omo-hyoid 

Scalenus  Amicus 
/  Sterno-cleido-mastoid 


,~ Clavicle  in  section 

#^--  Subclavius 

Axillary  Artery 
t:^  -^-  Axillary  Vein 

..Pectoralis  .Major  (cut) 


-Pectoralis  Minor 


\      \y      — 

'  .-\    \    \      ^.         \ Outer  Head  of  Medmn  Nerve 
-    \     \     \       \ 
Nerve  of  Wrisberg     ,■      \    \  v  ,.      ,     ^,r   j-       v 

Axillary  Vein       \    ^       Inner  Head  of  Median  Nerve 

Ulnar  Nerve        \  ^  _. 

Internal  Cutaneous  Nerve 

Fig.  172.— The  Axillary  Space,  after  Reflection  of  the  Pectoralis 
Major,   and  the  Subclavian  Triangle. 

magnus.  The  outer  wall,  which  is  very  circumscribed,  is  formed  by 
the  upper  part  of  the  humerus  and  the  common  origin  of  the  coraco- 
brachialis  and  short  head  of  the  biceps. 

Contents  and  their  Position.— The  axillary  vessels  and  the  nerves 
which  arise  from  the  brachial  plexus  lie  for  the  most  part  along  the 
outer  wall.  The  thoracic  axis  and  the  long  thoracic  artery  pass  to 
the  anterior  wall,  the  former  above  the  pectoralis  minor,  where  it 
pierces  the  costo-coracoid  membrane,  the  latter  along  the  lower 
border  of  that  muscle.  The  subscapular  artery  lies  on  the  posterior 
wall,  where  it  passes  inwards  on  the  lower  border  of  the  subscapu- 
laris. The  posterior  circumflex  artery  lies  for  a  short  distance  on  the 
jjosterior  wall,  but  soon  j)asses  backwards  between  the  subscapularis 
and  teres  major.     The  anterior  circumflex  artery  passes  outwards 


288  A   MANUAL  OF  ANATOMY 

in  front  of  the  humerus  beneath  the  coraco-brachialis  and  biceps. 
The  superior  thoracic  artery  is  above  the  thoracic  axis,  where  it 
takes  a  course  inwards  to  the  thoracic  wall. 

The  external  anterior  thoracic  nerve  pierces  the  costo-coracoid 
membrane  to  enter  the  deep  surface  of  the  pectoralis  major. 
The  internal  ■  anterior  thoracic  nerve  enters  the  deep  surface 
of  the  pectoralis  minor,  and  sends  branches  through  it  to  the 
major.  The  posterior  thoracic  nerve  descends  upon  the  inner  wall, 
resting  on  the  serratus  magnus.  The  intercosto-humeral  nerve 
pierces  the  second  intercostal  space,  and  crosses  the  axilla  to  the 
inner  side  of  the  arm.  Below  this  nerve,  on  the  thoracic  wall,  the 
succeeding  lateral  cutaneous  branches  of  intercostal  nerves  pierce 
the  intercostal  spaces,  and  the  posterior  branch  of  the  lateral 
cutaneous  of  the  third  intercostal  gives  a  branch  which  crosses  the 
axilla  to  the  inner  side  of  the  arm,  communicating  in  its  course 
with  the  intercosto-humeral.  The  three  subscapular  nerves  lie 
upon  the  posterior  wall,  and  supply  the  muscles  which  form  it. 
The  circumflex  nerve  lies  with  the  posterior  circumflex  artery,  which 
it  accompanies  in  its  backward  course.  The  musculo -spiral  nerve 
descends  behind  the  axillary  artery,  and  eventually  turns  to  the 
back  of  the  humerus,  but,  before  doing  so,  it  gives  off  its  internal 
cutaneous  branch.  The  median  nerve  is  upon  the  outer  side  of 
the  main  artery,  and  the  ulnar  nerve  is  internal  to  it,  between  it 
and  the  vein.  The  lesser  internal  cutaneous  nerve  is  on  the  inner 
side  of  the  vein,  and  the  internal  cutaneous  nerve  is  usually  met  with 
partly  over  the  line  of  the  main  artery  and  partly  on  its  inner  side. 

The  axillary  lymphatic  glands  are  arranged  in  three  sets — 
an  external,  lying  on  the  outer  wall  along  the  principal  blood- 
vessels ;  an  internal,  lying  along  the  course  of  the  long  thoracic 
artery  within  the  anterior  fold,  some  of  them  being  scattered  over 
the  adjacent  part  of  the  inner  wall  ;  and  a  posterior,  disposed  along 
the  course  of  the  subscapular  artery.  Besides  these  glands  there 
are  two  or  three  which  lie  upon  the  costo-coracoid  membrane 
where  that  is  pierced  by  the  cephalic  vein,  these  being  known  as 
the  infraclavicular  glands. 

Axillary  Artery. — The  axillary  artery  is  the  continuation  of  the 
subclavian,  and  it  extends  from  the  outer  border  of  the  first  rib  to 
the  lower  border  of  the  teres  major,  where  it  becomes  the  brachial. 
When  the  arm  is  by  the  side  of  the  trunk  the  vessel  describes  a  curve 
with  the  convexity  upwards,  but,  when  the  limb  is  abducted  to  the 
position  of  a  right  angle  to  the  trunk,  its  course  is  almost  straight.  In 
the  latter  position  of  the  limb  its  course  may  be  indicated  by  a  line 
drawn  from  the  centre  of  the  clavicle  to  the  inner  border  of  the 
coraco-brachialis.  The  artery  is  crossed  by  the  pectoralis  minor, 
and  is  thus  divided  into  three  parts — first,  second,  and  third. 

First  Part. — ^The  first  part  extends  from  the  outer  border  of  the 
first  rib  to  the  upper  border  of  the  pectoralis  minor,  and  it  is  about 
I  inch  long. 

Relations. — Anteriorly  it  is  covered  by  the  skin,  superficial  fascia, 


THE   UPPER  LIMB 


289 


origin  of  the  platysma  myoides,  deep  fascia,  clavicular  part  of  the 
pectoralis  major,  costo-coracoid  membrane,  axillary  sheath,  and 
the  lower  border  of  the  subclavius  when  the  shoulder  is  de- 
pressed. It  is  also  crossed  by  the  cephalic  and  acromio-thoracic 
veins,  and  the  communicating  loop  between  the  external  and 
internal  anterior  thoracic  nerves.  Posteriorly  it  rests  upon  the 
first  intercostal  space,  the  first  serration  of  the  serratus  magnus, 
and  the  upper  portion  of  the  second  rib,  with  the  intervention  of 


1  Long  Head  of  Biceps 

2  Tendon  of  Pectoralis  Major 

3  Short  Head  of  Biceps 

4  Coraco-brachialis 

5  Posterior  Circumflex  Artery 

6  Deltoid 

7  Subscapular  Artery 

8  Musculo-cutaneous  Nerve 

9  Cephalic  Vein 

10  Thoracic  Axis 

11  Pectoralis  .Nfinor 


20  19     18 


12  Pectoralis  Major  (Clavicular 

Portion) 

13  Subclavius 

14  Pectoralis  Major  (Sterno- 

costal Portion) 

15  Long  Thoracic  Artery 

16  Serratus  Magnus 

17  Posterior  Thoracic  Nerve 

18  Long  Subscapular  Nerve 

19  Subscapularis 

20  Lower  Subscapular  Nerve 


21  Dorsalis  Scapula;  Artery 

22  Intercosto-hunieral  Nerve 

23  Axillary  Vein 

24  Latissimus  Dorsi 

25  Teres  Major 

26  Nerve  of  Wrisberg 

27  Ulnar  Nerve 

28  Axillary  Artery 

29  Median  Nerve 

30  Internal  Cutaneous  Nerve 


Fig.   173. — The  Axillary  Space. 
(The  Pectoralis  Major  has  been  in  great  part  removed.) 

the  axillary  sheath,  and  the  posterior  thoracic  and  internal  anterior 
thoracic  nerves  lie  behind  it.  Externally,  and  above  it,  are  the 
three  cords  of  the  brachial  plexus.  Internally,  and  slightly  over- 
laj;ping  it,  is  the  axillary  vein. 

Second  Part. — The  second  part  lies  under  cover  of  the  pectoralis 
minor,  and  it  is  about  i^  inches  long. 

Relations. — Anteriorly  it  is  covered  by  the  integument,  and  the 
pectoralis  major  anrl  minor  muscles.    Posteriorly  is  the  posterior  cord 

19 


290  A  MANUAL  OF  ANATOMY 

of  the  brachial  plexus,  behind  which  is  a  quantity  of  fat,  separating 
the  vessel  from  the  subscapularis.  Externally  is  the  outer  cord  of 
the  brachial  plexus.  Internally  are  the  inner  cord  of  the  brachial 
plexus,  the  internal  anterior  thoracic  nerve,  and  the  axillary  vein. 

Third  Part. — The  third  part  extends  from  the  lower  border  of  the 
pectoralis  minor  to  the  lower  border  of  the  teres  major,  and  its 
length  is  about  3  inches.  The  upper  half  of  this  part  is  under  cover 
of  the  pectoralis  major,  but  the  lower  half  is  free  from  muscular 
covering,  which  is  due  to  the  posterior  wall  of  the  axilla  being  longer 
than  the  anterior. 

Relations. — Anteriorly  over  its  upper  half  it  is  covered  by  the 
integument  and  pectoralis  major,  and  over  its  lower  half  only  by  the 
integument  of  the  arm.  The  inner  root  of  the  median  nerve  crosses 
it  obliquely  from  within  outwards,  and  the  external  vena  comes  of 
the  brachial  artery  crosses  it  from  without  inwards.  Posteriorly 
it  rests,  from  above  downwards,  upon  the  subscapularis,  tendon  of 
the  latissimus  dorsi,  and  lower  part  of  the  teres  major,  and  the  cir- 
cumflex and  musculo -spiral  nerves  descend  behind  it.  Externally 
is  the  coraco-brachialis,  which  sometimes  slightly  overlaps  it.  The 
outer  root  of  the  median  nerve  lies  on  its  outer  side,  as  does  also  the 
musculo- cutaneous.  Internally  is  the  axillary  vein,  and,  for  a  short 
distance  below,  the  internal  vena  comes  of  the  brachial  artery. 
Between  the  axillary  vein  and  the  artery  are  the  inner  root  of  the 
median  nerve  and  the  ulnar  nerve  ;  internal  to  the  vein  is  the  lesser 
internal  cutaneous  nerve;  and  the  internal  cutaneous  nerve  is 
partly  on  the  artery  and  partly  to  its  inner  side. 

Branches. — ^The  first  part  gives  off  the  superior  or  short  thoracic, 
and  the  thoracic  axis  or  acromio-thoracic  artery.  The  second 
part  furnishes  the  inferior  or  long  thoracic,  and  the  alar  thoracic, 
which  is  very  inconstant  as  a  separate  branch.  The  third  part 
gives  off  the  subscapular,  the  anterior  circumflex,  and  the  posterior 
circumflex. 

Branches  of  the  First  Part.— The  superior  or  short  thoracic  artery 
is  a  small  branch  which  arises  just  below  the  subclavius.  Its  course 
is  inwards  and  downwards  behind  the  axillary  vein  to  the  first  two 
intercostal  spaces,  where  it  anastomoses  with  branches  of  the  first 
and  second  intercostal  arteries.  It  supplies  the  adjacent  intercostal 
muscles,  upper  part  of  the  serratus  magnus,  and  occasionally  the 
pectoral  muscles.  The  thoracic  axis  or  acromio-thoracic  artery  is 
a  short,  but  large,  trunk  which  arises  immediately  above  the  upper 
border  of  the  pectoralis  minor.  Passing  straight  forwards  it  pierces 
the  costo-coracoid  membrane,  and  then  divides  into  radiating 
branches,  called  thoracic,  acromial,  humeral,  and  clavicular.  The 
thoracic  branches  descend  between  the  two  pectoral  muscles  which 
they  supply.  The  acromial  branches  pass  outwards  over  the  cora- 
coid  process  to  the  deltoid,  in  which  some  of  them  end,  whilst  others 
pierce  that  muscle,  and  so  reach  the  upper  surface  of  the  acromion 
process,  where  they  anastomose  with  branches  of  the  suprascapular 
and  posterior  circumflex.     The  humeral  {descending)  branch  passes 


THE   UPPER  LIMB  291 

downwards  with  the  cephalic  vein  between  the  pectoralis  major  and 
deltoid,  to  the  contiguous  parts  of  which  muscles  it  is  distributed. 
The  clavicular  branch  passes  upwards  to  end  in  the  subclavius. 

Branches  of  the  Second  Part.— The  inferior  or  long  thoracic 
artery,  also  called  the  external  mammary,  is  directed  downwards 
and  inwards  along  the  lower  border  of  the  pectoralis  minor  to  the 
thoracic  wall.  It  is  distributed  to  the  pectoral  muscles,  serratus 
magnus,  and  intercostal  muscles,  and  it  sends  branches  round  the 
lower  border  of  the  pectoralis  major  to  the  mammary  gland.  It 
also  gives  branches  to  the  pectoral  group  of  axillary  glands,  and  it 
anastomoses  with  branches  of  the  aortic  intercostals  and  internal 
mammary.  The  alar  thoracic  artery  is  distributed  to  the  axillary 
glands.  It  is  seldom  a  special  branch,  its  place  being  usually  taken 
by  branches  of  the  long  thoracic  and  subscapular. 

Branches  of  the  Third  Part. — The  subscapular  artery,  which  is 
the  largest  of  all  the  branches  of  the  vessel,  arises  opposite  the  lower 
border  of  the  subscapularis,  along  which  it  courses  downwards  and 
inwards  to  the  lower  angle  of  the  scapula,  in  company  with  the  long 
subscapular  nerve,  where  it  anastomoses  with  the  posterior  scapular 
and  long  thoracic.  Besides  giving  branches  to  the  muscles  on  the 
posterior  wall,  the  serratus  magnus,  and  the  posterior  group  of 
axillary  glands,  it  gives  off  near  its  origin  a  large  branch,  called  the 
dorsalis  scapnlce.  This  vessel  at  once  passes  backwards  through  the 
triangular  space  bounded  above  by  the  subscapularis,  below  by  the 
teres  major,  and  externally  by  the  long  head  of  the  triceps.  There- 
after it  winds  round  the  back  of  the  axillary  border  of  the  scapula, 
piercing  the  origin  of  the  teres  minor  and  grooving  the  bone,  and  so 
it  reaches  the  infraspinous  fossa  beneath  the  infraspinatus.  Here 
it  breaks  up  into  numerous  branches,  which  supply  that  muscle  and 
the  bone,  and  which  anastomose  with  the  suprascapular  and  dorsal 
branches  of  the  posterior  scapular.  As  it  passes  through  the  tri- 
angular space  it  furnishes  a  ventral  branch  (infrascapular),  which 
ramifies  in  the  venter  of  the  scapula  beneath  the  subscapularis,  and 
anastomoses  with  the  ventral  branches  of  the  suprascapular  and 
posterior  scapular.  Before  piercing  the  teres  minor  it  gives  off  a 
descending  or  teres  branch,  which  passes  downwards  between  the 
teres  major  and  minor  as  far  as  the  lower  angle  of  the  scapula,  where 
it  anastomoses  with  the  terminal  part  of  the  posterior  scapular. 
The  dorsalis  scapuke  sometimes  arises  directly  from  the  axillary. 

The  anterior  circumflex  artery,  which  is  of  small  size,  arises 
from  the  outer  side  of  the  vessel  a  little  below  the  subscapular  and 
opposite  the  posterior  circumflex.  It  passes  outwards  in  front  of 
the  surgical  neck  of  the  humerus,  and  beneath  the  coraco-brachialis 
and  biceps.  On  reaching  the  bicipital  groove  it  gives  off  an  ascend- 
ing or  bicipital  branch,  which  passes  upwards  in  the  groove  with  the 
long  head  of  the  biceps,  to  be  distributed  to  the  shoulder- joint  and 
head  of  the  humerus.  Thereafter  it  continues  its  winding  course 
.  to  the  outer  side  of  the  bone,  where  it  anastomoses  with  the  pos- 
terior circumflex. 

19 — 2 


292  A  MANUAL  OF  ANATOMY 

The  posterior  circumflex  artery,  which  is  of  large  size,  arises 
from  the  back  of  the  vessel  a  little  below  the  subscapular.  Its 
course  is  backwards  in  company  with  the  circumflex  nerve  through 
the  quadrangular  space,  which  is  bounded  above  by  the  teres  minor 
(subscapularis  in  front),  below  by  the  teres  major,  internally  by  the 
long  head  of  the  triceps,  and  externally  by  the  surgical  neck  of  the 
humerus.  In  its  course  it  winds  round  the  inner  and  posterior 
aspects  of  the  neck  of  the  bone,  and  it  furnishes  many  branches,  most 
of  which  enter  the  deep  surface  of  the  deltoid.  A  special  acromial 
branch  reaches  the  upper  surface  of  the  acromion  process,  and  there 
anastomoses  with  the  suprascapular  and  acromial  branches  of  the 
thoracic  axis.  On  the  outer  side  of  the  neck  of  the  bone  the  artery 
anastomoses  with  the  anterior  circumflex,  and  in  this  way  an  arterial 
circle  is  formed  which  closely  embraces  the  surgical  neck.  Some  of 
the  branches  supply  the  muscles  bounding  the  quadrangular  space, 
and  one  or  two  pass  downwards  between  the  long  and  outer  heads 
of  the  triceps,  where  they  anastomose  with  the  superior  profunda 
of  the  brachial.  The  posterior  circumflex  artery  is  subject  to 
certain  variations,  (i)  It  may  arise  in  common  with  the  sub- 
scapular. (2)  Its  origin  may  be  transferred  to  the  superior  pro- 
funda of  the  brachial,  in  which  case  it  ascends  behind  the  teres 
major.  (3)  It  may  give  off  the  anterior  circumflex,  superior  pro- 
funda, or  dorsalis  scapula. 

Varieties    of   the   Axillary   Artery (i)  The  subscapular,  circumflex,  and 

profunda  of  the  brachial  may  arise  by  a  common  trunk.  (2)  The  artery  may 
give  origin  to  a  large  branch,  which  maybe  the  radial,  ulnar,  vas  aberrans,  or 
the  interosseous  trunk  of  the  forearm. 

The  part  of  the  axillary  artery  most  accessible  for  surgical  interference  is 
the  lower  half  of  the  third  part,  which  is  covered  only  by  the  integument  of 
the  arm. 

Axillary  Vein. — ^The  axillary  vein  is  the  continuation  of  the  basilic 
vein  of  the  arm.  It  extends  from  the  lower  border  of  the  teres 
major  to  the  outer  border  of  the  first  rib,  where  it  becomes  the  sub- 
clavian vein.  It  is  of  large  size,  and  throughout  its  entire  course  it 
lies  to  the  inner  side  of  the  artery.  Most  of  its  tributaries  corre- 
spond with  the  arterial  branches,  but  the  following  two  are  specially 
noteworthy  :  (i)  a  little  above  its  commencement  it  receives  the 
trunk  formed  by  the  union  of  the  venae  comites  of  the  brachial 
artery,  and  (2)  below  the  clavicle  it  is  joined  by  the  cephalic  vein. 

Axillary  Sheath. — The  axillary  vessels  and  the  brachial  plexus  of 
nerves  are  enclosed  in  a  loose,  infundibuliform  sheath,  which  is 
called  the  axillary  sheath.  It  is  a  downward  prolongation  of  the 
deep  cervical  fascia,  and  it  blends  with  the  deep  surface  of  the 
costo-coracoid  membrane.  It  has  been  compared  to  the  crural 
sheath  of  the  femoral  vessels,  but  it  is  in  no  sense  such  a  defined 
structure. 

Brachial  Plexus. — ^The  brachial  plexus  is  situated  in  the  lower  part 
of  the  posterior  triangle  of  the  neck,  behind  the  clavicle,  and  in  the 
upper  part  of  the  axilla.     Its  complex  formation  is  rendered  simple 


THE  UPPER  LIMB  293 

by  arranging  it  into  four  stages,  namely,  (i)  nerve  roots,  (2)  ner\'e 
trunks,  (3)  divisions  of  nerve  trunks,  and  (4)  nerve  cords. 

First  Stage. — The  nerves  which  form  the  plexus  are  the  anterior 
primary  divisions  of  the  fifth,  sixth,  seventh,  and  eighth  cervical,  and 
the  greater  part  of  that  of  the  first  thoracic.  Superiorly  the  plexus 
is  reinforced  by  a  small  descending  branch  from  the  fourth  cervical, 
which  joins  the  fifth,  and  inferiorly  it  is  occasionally  reinforced  by  a 
branch  from  the  second  thoracic,  which  joins  the  first.  As  regards 
the  first  thoracic  nerve,  the  part  of  it  which  does  not  join  the  plexus, 
and  which  is  of  small  size,  enters  the  first  intercostal  space  to  become 
the  first  intercostal  nerve.  The  nerves,  as  they  emerge  at  the  side 
of  the  neck,  are  placed  between  the  scalenus  anticus  and  scalenus 
medius. 

Second  Stage.— The  fifth  and  sixth  cervical  nei'ves  join  at  the  outer 
border  of  the  scalenus  anticus  to  form  the  upper  trunk  :  the  seventh 
cervical  remains  meanwhile  single,  and  forms  the  middle  trunk  ; 
and  the  eighth  cervical  and  greater  part  of  the  first  thoracic  unite 
between  the  scalene  muscles  to  form  the  lower  trunk.  There  are 
thus  three  trunks — upper,  middle,  and  lower. 

Third  Stage.- — A  little  above  the  clavicle  each  of  the  three  trunks 
breaks  up  into  an  anterior  and  a  posterior  division. 

Fourth  Stage. — The  anterior  divisions  of  the  upper  and  middle 
trunks  unite  to  form  the  outer  cord  of  the  plexus  ;  the  anterior 
division  of  the  lower  trunk,  which  is  of  large  size,  forms  the  inner 
cord  ;  and  all  three  posterior  divisions  (that  of  the  lower  trunk  being 
of  small  size)  unite  to  form  the  posterior  cord.  As  a  variety,  the 
anterior  division  of  the  middle  trunk  may  subdivide  into  two 
branches,  one  entering  the  outer  cord  and  the  other  the  inner. 
There  are  thus  three  cords — outer,  inner,  and  posterior. 

Branches  of  the  Plexus. — The  branches  are  conveniently  divided 
into  two  groups — supraclavicular,  arising  above  the  clavicle  and 
coming  from  nerve  roots  and  nerve  trunks  ;  and  infraclavicular, 
arising  below  the  clavicle  and  coming  from  nerve  cords. 

Supraclavicular  Braftches. — ^These  are  as  follows  :  Muscular 
branches  from  the  four  cervical  nerves  to  the  scalene  muscles  and 
longus  colli. 

One  root  of  the  phrenic  nerve  (inconstant)  from  the  front  of  the 
fifth  cervical. 

The  Nerve  to  the  Rhomboids. — This  branch  arises  from  the 
back  of  the  fifth  cervical  close  to,  or  along  with,  the  highest  root  of 
the  posterior  thoracic,  and  it  takes  a  backward  course  through  the 
scalenus  medius. 

The  Posterior  Thoracic  Nerve  or  External  Respiratory  Nerve  of 
Bell. — This  branch  arises  by  three  roots  from  the  back  of  the  fifth, 
sixth,  and  seventh  cervical  nerves.  The  upper  two  roots  pierce  the 
scalenus  medius  below  the  nerve  to  the  rhomboids,  either  conjointly 
or  separately,  whilst  the  lowest  root  passes  in  front  of  the  scalenus 
medius,  and  joins  the  trunk  formed  by  the  others  near  the  first  rib. 
The  nerve  then  courses  behind  the  first  part  of  the  axillary  artery, 


294 


A  MANUAL  OF  ANATOMY 


and  subsequently  descends  upon  the  axillary  surface  of  the  serratus 
magnus,  supplying  branches  to  all  its  serrations. 

The  Nerve  to  the  Subelavius.— This  small  branch  arises  from  the 
front  of  the  upper  trunk,  its  fibres  being  derived  from  the  fifth 
cervical.  It  descends  over  the  third  part  of  the  subclavian  artery, 
and,  passing  behind  the  clavicle,  it  enters  the  subelavius  muscle 
on  its  deep  aspect.  This  nerve  sometimes  communicates  with  the 
phrenic  nerve. 

The  Suprascapular  Nerve. — This  is  a  large  nerve  which  arises 


To  Cervical  Plexus  - 

To  Brachial  Plexus^^ 

Third  Root  of  Phrenic  (inconstant)^ 
Nerve  to  the  Rhomboids^ 
Nerve  to  Subelavius 
Suprascapular 


External  Anterior  Thoracic 

Circumflex 
Musculo-spiral     \ 

Outer  Head  of  Median 
Musculo-cutaneous 

^Median 


4.C. 


5,C. 


6.C. 


7.C. 


8.C. 


'  Posterior  Thoracic  (Ext. 
^  Respiratory  N.  of  Bell). 

^     V      \  First  Intercostal 

\    \      ■  Upper  or  Short  Subscapular 
\    "Internal  Anterior  Thoracic 
Middle  or  Long  Subscapular 
\  Lower  Subscapular 

Nerve  of  Wrisberg 

.  Inner  Head  of  Median 
\  Internal  Cutaneous 

""•Ulnar 

Fig.   174. — The  Brachial  Plexus. 

Yellow  =  Spinal  Nerves  and  their  Branches;  Blue  =  Trunks;  Red  =  Outer  Cord  ; 
Purple  =  Inner  Cord  ;   Grey  =  Posterior  Cord . 

from  the  back  of  the  upper  trunk,  its  fibres  being  derived  from  the 
fifth  and  sixth  cervical.  It  is  directed  downwards,  outwards,  and 
backwards  beneath  the  trapezius  and  posterior  belly  of  the  omo- 
hyoid to  the  upper  border  of  the  scapula,  on  approaching  which  it 
gets  in  company  with  the  suprascapular  artery.  It  is  distributed 
to  the  supraspinatus,  infraspinatus,  and  shoulder-joint. 

Infraclavicular  Branches. — Outer  Cord. — The  branches  of  this  cord 
are  the  external  anterior  thoracic,  musculo-cutaneous,  and  outer 
root  of  the  median. 

The  external  anterior  thoracic,  which  derives  its  fibres  from  the 


THE  UPPER  LIMB  295 

fifth,  sixth,  and  seventh  cervical,  crosses  over  the  first  part  of  the 
axihary  artery  fi-om  without  inwards,  and  gives  a  branch  to  the 
internal  anterior  thoracic.  Thereafter  it  pierces  the  costo-cora- 
coid  membrane,  and  is  distributed  to  the  pectoralis  major. 

The  musculo-cutaneous  or  perforating  nerve  of  Casserius,  which 
derives  its  fibres  from  the  fifth,  sixth,  and  seventh  cervical,  arises 
about  the  level  of  the  pectoralis  minor.  For  a  short  distance  it 
lies  on  the  outside  of  the  axillary  artery,  but  it  soon  leaves  the 
vessel,  and  pierces  the  coraco-brachialis  in  a  direction  downwards 
and  outwards.  Before  reaching  the  muscle  it  parts  with  a  branch 
to  it,  which  usually  enters  it  in  two  divisions.  The  fibres  of  this 
branch  are  derived  from  the  seventh  cervical.  The  subsequent 
course  of  the  musculo-cutaneous  will  be  described  later  on. 

The  outer  root  of  the  median  passes  slightly  on  to  the  axillary 
artery,  where  it  is  joined  by  the  inner  root. 

Inner  Cord. — The  branches  of  this  cord  are  the  internal  anterior 
thoracic,  the  lesser  internal  cutaneous  or  nerve  of  Wrisberg,  the 
internal  cutaneous,  inner  root  of  the  median,  and  ulnar. 

The  internal  anterior  thoracic  nerve,  which  derives  its  fibres 
from  the  eighth  cervical  and  first  thoracic,  passes  behind  the  first 
part  of  the  axillary  artery,  and  then  comes  forwards  between  the 
artery  and  the  axillary  vein.  Having  received  a  branch  from  the 
external  anterior  thoracic  nerve,  which  forms  a  loop  over  the  first 
part  of  the  artery,  it  breaks  up  into  branches  which  enter  the  deep 
surface  of  the  pectoralis  minor,  a  few  of  them  piercing  that  muscle 
to  enter  the  deep  surface  of  the  pectoralis  major. 

The  lesser  internal  cutaneous  or  nerve  of  Wrisberg,  which  derives 
its  fibres  from  the  first  thoracic,  is  at  first  placed  behind  the  axillary 
vein,  but  subsequently  descends  on  its  inner  side,  where  it  communi- 
cates with  the  intercosto-humeral  nerve.  This  nerve  is  sometimes 
absent. 

The  internal  cutaneous,  which  derives  its  fibres  from  the  eighth 
cervical  and  first  thoracic,  descends  partly  on  the  axillary  artery 
and  partly  to  its  inner  side. 

The  inner  root  of  the  median,  which  is  of  smaller  size  than  the 
outer,  passes  obliquely  over  the  axillary  artery,  and  joins  the  outer 
root  a  little  below  the  lower  border  of  the  pectoralis  minor.  The 
trunk  of  the  nerve,  which  derives  its  fibres  from  all  the  nerves  of  the 
plexus,  then  descends  on  the  outer  side  of  the  third  part  of  the 
artery. 

The  ulnar  nerve  is  the  largest  branch  of  the  inner  cord,  of  which  it 
is  the  continuation,  and  it  derives  its  fibres  from  the  eighth  cervical 
and  first  thoracic.  It  appears  at  the  lower  border  of  the  pectoralis 
minor,  and  then  descends,  lying  deeply  between  the  third  part  of 
the  axillary  artery  and  the  vein. 

Posterior  Cord. — ^The  branches  of  this  cord  are  the  three  sub- 
scapular nerves,  circumflex,  and  musculo-spiral. 

The  subscapular  nerves  are  distinguished  as  upper  or  short, 
middle  or  long,  and  lower.     The  upper  or  short  subscapular  nerve, 


296  A  MANUAL  OF  ANATOMY 

which  is  of  small  size,  derives  its  fibres  from  the  fifth  and  sixth 
cervical.  It  is  situated  high  up  on  the  posterior  wall  of  the  axilla, 
and  after  a  short  course  it  enters  the  upper  part  of  the  subscapu- 
laris.  The  middle  or  long  subscapular  nerve  derives  its  fibres 
chiefly  from  the  seventh  cervical,  but  to  a  certain  extent  also  from 
the  sixth  and  eighth.  It  descends  along  with  the  subscapular 
artery  to  the  latissimus  dorsi,  which  it  supplies.  The  lower  sub- 
scapular nerve  derives  its  fibres  from  the  fifth  and  sixth  cervical. 
On  approaching  the  lower  border  of  the  subscapularis  it  breaks 
up  into  branches,  some  of  which  enter  the  lower  part  of  that  muscle, 
whilst  others  pass  to  the  teres  major. 

The  circumflex  nerve  derives  its  fibres  from  the  fifth  and  sixth 
cervical.  For  a  short  distance  it  lies  behind  the  axillary  artery, 
resting  on  the  subscapularis,  but,  at  the  lower  border  of  that  muscle, 
it  passes  backwards  through  the  quadrangular  muscular  space  in 
company  with  the  posterior  circumflex  artery.  In  doing  so  it 
furnishes  an  articular  branch  to  the  shoulder- joint,  and  then  breaks 
up  into  an  upper  or  anterior  and  a  lower  or  posterior  division. 
The  upper  or  anterior  division  accompanies  the  posterior  circumflex 
artery,  and  divides  into  a  number  of  branches  which  enter  the 
deep  surface  of  the  deltoid  over  its  anterior  part.  Some  of  the 
branches,  piercing  the  muscle,  supply  the  integument  over  about  its 
middle  third.  The  loiver  or  posterior  division  gives  branches  to  the 
posterior  part  of  the  deltoid,  a  branch  to  the  teres  minor,  and  a 
cutaneous  branch,  which  latter  turns  round  the  posterior  border  of 
the  deltoid  to  be  distributed  to  the  integument  over  its  lower  third. 
The  nerve  to  the  teres  minor  presents  a  small  reddish  swelling, 
which  has  the  appearance  of  a  ganglion,  but  is  really  a  fibrous 
thickening. 

In  connection  with  the  distribution  of  the  circumflex  nerve 
Hilton's  law  may  be  here  stated  as  follows :  a  nerve  trimk,  supply- 
ing a  given  joint,  also  supplies  the  muscles  moving  that  joint,  and 
the  integument  covering  their  insertions.  For  example,  the  circum- 
flex nerve  supplies  the  shoulder- joint,  the  deltoid,  and  the  integu- 
ment covering  its  insertion.  This  law,  however,  is  not  universally 
applicable. 

The  musculo-spiral  nerve  is  the  largest  of  all  the  branches  of  the 
plexus,  and  is  the  continuation  of  the  posterior  cord.  It  derives  its 
fibres  from  the  last  four  cervical  nerves,  and  sometimes  from  the  first 
thoracic.  It  descends  behind  the  third  part  of  the  axillary  artery, 
resting  upon  the  subscapularis,  latissimus  dorsi,  and  teres  major. 
Whilst  in  the  axillary  space  it  gives  off  muscular  and  cutaneous 
branches.  The  muscular  branches  are  destined  for  the  long  and 
inner  heads  of  the  triceps,  those  for  the  long  head  entering  it 
high  up,  whilst  those  for  the  inner  head  enter  it  at  different  levels. 
One  of  the  latter,  which  is  remarkable  for  its  length,  descends 
in  company  with  the  ulnar  nerve  to  enter  the  inner  head  low 
down,  this  branch  being  known  as  the  ulnar  collateral  nerve 
(Krause).    The  internal  cutaneous  branch  usually  arises  in  common 


THE  UPPER  LIMB  297 

with  one  of  the  muscular  branches,  and  it  takes  a  backward  course 
behind  the  intercosto-humeral  nerve  to  be  distributed  to  the 
integument  of  the  back  of  the  arm,  reaching  nearly  as  low  as  the 
elbow. 

Intercosto-humeral  Nerve. — The  intercosto-humeral  nerve  is  the 
undivided  lateral  cutaneous  branch  of  the  second  intercostal,  and 
it  represents  the  posterior  branch  of  the  other  lateral  cutaneous 
nerves.  Emerging  from  the  second  intercostal  space  it  appears 
between  two  serrations  of  the  serratus  magnus,  and  then  crosses 
the  axillary  space.  In  its  course  it  usually  communicates  with  a 
branch  of  the  posterior  division  of  the  lateral  cutaneous  of  the  third 
intercostal,  and  towards  the  arm  it  also  communicates  with  the 
nerve  of  Wrisberg  and  the  internal  cutaneous  of  the  musculo-spiral. 
On  reaching  the  arm  it  is  distributed  to  the  integument  of  the 
inner  and  back  part  over  the  upper  half.  Sometimes  there  is 
another  intercosto-humeral  nerve,  which  is  the  undivided  lateral 
cutaneous  branch  of  the  first  intercostal  nerve.  When  this  is  so 
the  nerve  of  Wrisberg  is  absent. 

The  lateral  cutaneous  nerves  have  been  previously  described  in 
connection  with  the  cutaneous  nerves  of  the  pectoral  region  on 
page  279.  It  may  be  stated,  in  addition,  that  the  posterior  branch 
of  the  lateral  cutaneous  of  the  third  intercostal,  as  a  rule,  gives 
a  branch  across  the  axilla  to  the  inner  side  of  the  arm,  which 
communicates  in  its  course  with  the  intercosto-humeral,  and  may 
largely  replace  it,  if  it  is  small. 

Axillary  Glands. — ^The  axillary  glands  are  about  twelve  in  num- 
ber, and  are  arranged  in  three  groups,  which  communicate  freely 
with  one  another,  as  follows  :  (i)  an  external  group,  consisting  of 
about  five  glands,  lying  upon  the  outer  wall  along  the  course  of  the, 
axillary  vessels,  and  receiving  their  afferent  vessels  from  the  limb  ; 
(2)  an  antero-internal  or  pectoral  group,  about  five  in  number,  lying 
within  the  anterior  fold  along  the  course  of  the  long  thoracic  artery, 
one  or  two  of  them  being  placed  internally  on  the  serratus  magnus, 
and  receiving  their  afferent  vessels  from  the  greater  part  of  the 
mammary  gland  and  the  front  of  the  chest  ;  and  (3)  a  posterior  or 
subscapular  group,  two  or  three  in  number,  situated  on  the  posterior 
wall  along  the  course  of  the  subscapular  artery,  and  receiving  their 
afferent  vessels  from  the  back  of  the  trunk.  Besides  these  three 
groups  there  is  an  infraclavicular  group,  two  or  three  in  number, 
which  lie  below  the  clavicle,  in  the  interval  between  the  pectoralis 
major  and  deltoid,  and  are  in  communication  below  with  the 
axillary  glands  and  above  with  the  glands  at  the  root  of  the  neck. 
The  glands  of  this  group  receive  their  afferent  vessels  from  the 
shoulder  and  outer  side  of  the  arm.  The  efferent  vessels  of  all  the 
foregoing  glands  terminate  on  the  left  side  in  the  thoracic  duct,  and 
on  the  right  side  in  the  right  lymphatic  duct,  having  followed  the 
course  of  each  subclavian  vein.  In  some  cases  they  are  gathered 
up,  on  each  side,  into  one  vessel,  called  the  axillary  lymphatic 
trunk. 


298 


A   MANUAL  OF  ANATOMY 


Serratus  Magnus — Origin. — The  outer  surfaces  of  the  first  eight 
or  nine  ribs  about  midway  between  the  angles  and  costal  cartilages, 
by  means  of  fleshy  serrations  which  are  curved  with  their  convexities 
forwards.  Each  serration  arises  from  one  rib,  except  the  first, 
which  arises  from  the  first  and  second  ribs  and  a  fibrous  arch  between 
them. 

Insertion. — ^The  anterior  surface  of  the  base  of  the  scapula  from  the 
superior  to  the  inferior  angle. 

Nerve-sup-ply. — ^The  posterior  thoracic  nerve,  which  arises  by 
three  roots  from  the  fifth,  sixth,  and  seventh  cervical.  The  nerve 
descends  on  the  axillary  surface  of  the  muscle. 


Subscapularis 


!    Abdominis 


Fig.   175. — The  Serratus  Magnus  Muscle. 


The  muscle  is  arranged  in  three  parts.  The  upper  part  is  formed 
by  the  first  serration,  which  is  of  large  size,  and  it  is  inserted 
into  the  triangular  area  on  the  front  of  the  superior  angle  of  the 
scapula.  The  middle  part  forms  a  thin,  expanded  sheet,  which  is 
formed  by  the  broad  second  and  the  third  serrations,  and  it  is  inserted 
into  the  long,  linear  impression  on  the  front  of  the  base,  reaching 
to  near  the  superior  angle  and  extending  down  to  near  the  inferior 
angle.  The  lower  part,  which  is  formed  by  the  lower  five  or  six 
serrations,  is  fan- shaped,  and  towards  the  scapula  is  thick  and 
stout,  its  insertion  being  into  the  expanded  area  in  front  of  the 
inferior  angle.  The  lower  four  or  five  serrations  inter  digitate  with 
the  obliquus  externus  abdominis. 


THE  UPPER  LIMB  299 

Action. — ^The  muscle  draws  the  base  of  the  scapula  forwards,  as 
in  pushing,  and  the  strong  lower  fibres,  acting  upon  the  lower  angle, 
rotate  the  bone  so  as  to  elevate  the  point  of  the  shoulder.  In  this 
latter  action  the  muscle  is  auxiliary  to  the  trapezius.  An  im- 
portant use  of  the  muscle  is  to  steady  the  scapula,  more  particularly 
the  glenoid  cavity,  this  condition  being  necessary  before  the  deltoid 
can  elevate  the  humerus.  The  muscle  by  its  contraction  serves 
to  keep  the  lower  angle  of  the  scapula  in  contact  with  the  chest 
wall.  When  the  shoulder  is  fixed  the  lower  part  of  the  muscle  may 
elevate  the  ribs  from  which  it  arises. 


THE  SCAPULAR  REGION. 

Cutaneous  Nerves. — ^The  cutaneous  nerves  of  the  shoulder  are 
derived  from  the  supra-acromial  of  the  cervical  plexus  and  the  cir- 
cumflex. The  supra-acromial  nerve,  having  descended  over  the 
outer  part  of  the  clavicle  and  trapezius,  divides  into  numerous 
branches,  which  supply  the  integument  over  the  upper  third  of 
the  deltoid.  The  circumflex  nerve  sends  branches  through  the 
muscle  which  supply  the  integument  over  about  its  middle  third. 
It  also  furnishes  a  special  cutaneous  branch  which  turns  round  the 
posterior  border  of  the  muscle  a  little  below  the  centre,  and  supplies 
the  integument  over  its  lower  third. 

Deep  Fascia. — ^The  deep  fascia  is  well  marked  over  the  infra- 
spinatus, where  it  is  strongly  aponeurotic.  It  sends  septa  between 
that  muscle  and  the  teres  muscles,  and  then  passes  forwards  over 
them  to  the  posterior  border  of  the  deltoid,  where  it  splits  into  two 
layers  which  encase  that  muscle. 

Deltoid — Origin. — (i)  The  anterior  border  of  the  outer  third 
of  the  clavicle  ;  (2)  the  outer  border  of  the  acromion  process  ; 
and  (3)  the  lower  lip  of  the  posterior  border  of  the  spine  of  the 
scapula. 

Insertion. — The  deltoid  impression  on  the  outer  aspect  of  the 
humerus,  commencing  at  the  centre,  and  extending  upwards  for 
2  inches  or  more. 

Nerve-supply. — The  circumflex  nerve,  which  is  a  branch  of  the 
posterior  cord  of  the  brachial  plexus,  its  fibres  being  derived  from 
the  fifth  and  sixth  cervical. 

Blood-supply. — ^The  posterior  circumflex  and  acromio- thoracic 
arteries. 

The  muscle,  which  has  very  coarse  fasciculi,  is  triangular,  the 
base  being  upwards.  The  clavicular  portion  passes  downwards  and 
outwards,  the  acromial  downwards,  and  the  spinal  downwards  and 
forwards. 

Action. — The  acromial  portion  abducts  the  arm  to  the  position  of 
a  right  angle  with  the  trunk  ;  the  clavicular  portion  draws  it  for- 
wards; and  the  spinal  portion  draws  it  backwards. 

The  acromial  jjortion  of  the  muscle,  besides  arising  from  the  bone, 


300  A  MANUAL  OF  ANATOMY 

springs  to  a  large  extent  from  the  sides  of  four  fibrous  septa,  which 
descend  into  that  part,  and  the  fibres  arising  in  this  manner  are 
inserted  into  the  sides  of  three  fibrous  septa,  which  ascend  from 
below. 

The  origin  of  the  muscle  corresponds  with  the  insertion  of  the 
trapezius.  The  anterior  border  is  related  to  the  pectoralis  major, 
the  cephalic  vein  and  humeral  artery  lying  between  the  two.  The 
posterior  border  is  to  a  large  extent  bound  down  by  the  splitting  of 
the  deep  fascia  over  the  infraspinatus.  The  muscle  covers  the 
shoulder-joint,  subacromial  bursa,  coracoid  process,  coraco-brachi- 
alis,  biceps,  tendons  of  insertion  of  the  supraspinatus,  infraspinatus, 
and  teres  minor,  parts  of  the  long  and  outer  heads  of  the  triceps, 
teres  major,  tendon  of  insertion  of  the  pectoralis  major,  circumflex 
nerve,  and  posterior  circumflex  artery. 

Subacromial  Bursa. — This  is  a  large  bursa  which  intervenes 
between  the  acromion  process  and  deltoid,  on  the  one  hand,  and 
the  upper  part  of  the  capsular  ligament  and  the  tendons  inserted 
into  the  great  tuberosity  of  the  humerus,  on  the  other. 

Supraspinatus  —  Origin. — The  inner  two- thirds  of  the  supra- 
spinous fossa  of  the  scapula,  and  the  aponeurosis  covering  the 
muscle. 

Insertion. — The  upper  impression  on  the  great  tuberosity  of  the 
humerus,  its  tendon  being  closely  connected  with  the  upper  part  of 
the  capsular  ligament,  and  with  that  of  the  infraspinatus. 

Nerve- stipply. — The  suprascapular  nerve,  which  arises  from  the 
back  of  the  upper  trunk  of  the  brachial  plexus,  its  fibres  being 
derived  from  the  fifth  and  sixth  cervical. 

The  direction  of  the  muscle  is  outwards  and  downwards. 

Action. — To  abduct  the  arm  in  association  with  the  deltoid. 

Posterior  Belly  of  the  Omo-hyoid — Origin. — The  upper  border 
of  the  scapula  internal  to  the  suprascapular  notch,  and,  as  a 
rule,  the  adjacent  portion  of  the  suprascapular  or  transverse 
ligament. 

Infraspinatus — Origin. — (i)  The  infraspinous  fossa  of  the  scapula 
over  about  its  inner  two- thirds,  the  parts  excepted  being  those  for 
the  teres  muscles,  and  a  portion  at  the  upper  and  outer  part  of  the 
fossa  ;  and  (2)  the  deep  fascia  covering  the  muscle. 

Insertion. — ^The  middle  impression  on  the  great  tuberosity  of 
the  humerus,  its  tendon  being  closely  connected  with  the  back  part 
of  the  capsular  ligament,  from  which  it  is  sometimes  separated  by 
a  bursa.  The  tendon,  which  is  fan-shaped,  is  at  first  concealed 
within  the  muscle. 

Nerve-supply. — The  suprascapular  nerve. 

The  direction  of  the  muscle  is  outwards. 

Action. — When  the  arm  is  by  the  side  of  the  trunk  the  muscle  is 
an  external  rotator.  When  the  arm  is  raised  the  muscle  carries  it 
backwards  in  association  with  the  deltoid. 

Suprascapular  Artery. — The  suprascapular  artery  (transversalis 
humeri)  is  a  branch  of  the  thyroid  axis  of  the  first  part  of  the  sub- 


THE   UPPER  LIMB  301 

clavian.  Having  coursed  transversely  outwards  behind  the  clavicle, 
it  reaches  the  upper  border  of  the  scapula  in  company  with  the 
suprascapular  nerve.  The  artery  then  passes  backwards  over  the 
suprascapular  ligament,  whilst  the  nerve  passes  beneath  it,  and  it 
descends  into  the  supraspinous  fossa  beneath  the  supraspinatus, 
where  it  parts  with  several  branches.  Thereafter  it  passes 
behind  the  neck  of  the  scapula  through  the  great  scapular  notch, 
beneath  the  spino-glenoid  ligament,  into  the  upper  and  outer 
part  of  the  infraspinous  fossa  under  cover  of  the  infraspinatus, 
where  it  anastomoses  with  the  dorsalis  scapulae  and  posterior 
scapular. 

Branches. — These  are  as  follows :  muscular,  in  the  neck,  to  the 
sterno-cleido-mastoid  and  subclavius  ;  suprasternal,  over  the  inner 
end  of  the  clavicle,  to  the  integument  over  the  presternum ; 
niedullarv  to  the  clavicle  ;  snpra-acromial,  which  pierces  the 
trapezius  to  reach  the  upper  surface  of  the  acromion  process,  where 
it  anastomoses  with  branches  of  the  acromio- thoracic  and  posterior 
circumflex  ;  articular  to  the  acromio-clavicular  and  shoulder- 
joints  ;  ventral  to  the  belly  of  the  scapula,  given  off  as  it  passes 
backwards  over  the  suprascapular  ligament,  this  branch  anasto- 
mosing with  the  ventral  branches  of  the  dorsalis  scapulae  and 
posterior  scapular  ;  supraspinous  to  the  fossa  and  its  muscle  ;  and 
infraspinous  to  the  fossa  and  its  muscle. 

Suprascapular  Nerve. — This  nerve  passes  backwards  beneath  the 
suprascapular  ligament  into  the  supraspinous  fossa,  where  it  gives 
branches  to  the  supraspinatus,  and  articular  branches  to  the  acromio- 
clavicular and  shoulder-joints.  It  then  accompanies  the  artery 
through  the  great  scapular  notch,  beneath  the  spino-glenoid  ligament, 
to  the  infraspinous  fossa,  where  it  ends  in  branches  to  the  infra- 
spinatus. 

Teres  Minor — Origin. — (i)  The  dorsum  of  the  scapula  close  to  the 
axillary  border  for  its  upper  two-thirds,  and  (2)  the  septa  between 
it  and  the  infraspinatus  and  teres  major. 

Insertion. — ^The  lower  impression  on  the  great  tuberosity  of  the 
humerus,  and  the  surgical  neck  of  the  bone  for  a  short  distance 
below,  its  tendon  being  closely  connected  with  the  back  part  of  the 
capsular  ligament. 

Nerve-supply. — The  circumflex  nerve,  the  branch  of  which  has  a 
reddish  enlargement  presenting  the  appearance  of  a  ganglion,  but 
being  in  reality  a  fibrous  thickening. 

The  direction  of  the  muscle  is  outwards  and  slightly  upwards. 

Action. — The  muscle  is  an  external  rotator  of  the  arm  when  it  is 
abducted,  and  it  also  helps  in  depressing  the  arm. 

The  muscle  is  pierced  by  the  dorsalis  scapulae  artery. 

Teres  Major — Origin. — (i)  From  an  oval  impression  at  the  lower 
and  outer  j^art  of  the  infraspinous  fossa,  which  extends  on  to  the 
lower  angle,  and  reaches  upwards  on  the  axillary  border  for  about 
its  lower  third  ;  and  (2)  the  septa  between  it  and  the  teres  minor, 
infraspinatus,  and  subscapularis. 


302 


A  MANUAL  OF  ANATOMY 


Insertion. — The  inner  lip  of  the  bicipital  groove  of  the  humerus 
for  2  inches  over  about  its  lower  two-thirds. 

Nerve-siipply. — ^The  lower  subscapular  nerve,  which  is  a  branch  of 
the  posterior  cord  of  the  brachial  plexus,  its  fibres  being  derived 
from  the  fifth  and  sixth  cervical. 

The  direction  of  the  muscle  is  outwards. 


Supraspinatus 


—Infraspinatus 


.Teres  Minor 


Teres  Major  ^ 


Teres  Branch  of  Dorsalis' 
Scapulas  Artery 
Dorsalis  Scapulas  Artery  in^ 
Triangular  Space 
Nerve  to  Teres  Minor,  with 
Gangliform  Enlargement 


— Posterior  Circumflex  Artery 

and  Circumflex  Nerve  in 

Quadrangular  Space 


-,Pectoralis  Major 


-.Deltoid 


Fig.    176. — Dissection  of  the  Scapular  and  Upper  Brachial  Regions 

FROM  Behind. 

(The  Deltoid  has  been  turned  down,  and  the  Triangular  and  Quadrangular 
Muscular  Spaces,  with  their  contents,  are  shown.) 


A  ction. — ^The  muscle  adducts  the  arm.  When  the  arm  is  abducted 
it  acts  as  an  internal  rotator. 

The  latissimus  dorsi  winds  round  the  lower  border  of  the  muscle, 
and  is  subsequently  placed  in  front  of  it.  The  two  tendons  are 
at  first  closely  connected  by  their  lower  borders,  but  are  after- 


THE   UPPER  LIMB  303 

wards  separated  by  a  bursa,  and  there  is  usually  a  bursa  behind 
the  teres  major  at  its  insertion. 

Subscapularis — Origin. — (i)  The  venter  of  the  scapula,  except 
near  the  neck,  and  along  the  front  of  the  base  where  the  serratus 
magnus  is  inserted  ;  and  (2)  the  sides  of  tendinous  septa  which 
intersect  the  muscle  and  are  connected  with  the  ridges  on  the 
venter. 

Insertion. — ^The  small  tuberosity  of  the  humerus,  and  the  surgical 
neck  of  the  bone  for  a  short  distance  below. 

Nerve-supply. — The  upper  or  short,  and  part  of  the  lower,  sub- 
scapular nerves,  which  are  branches  of  the  posterior  cord  of  the 
brachial  plexus,  their  fibres  being  derived  from  the  fifth  and  sixth 
cervical. 

The  direction  of  the  muscle  is  outwards. 

Action. — When  the  arm  is  by  the  side  of  the  trunk  the  muscle  is 
an  internal  rotator,  and,  when  it  is  raised,  it  carries  it  forwards  and 
downwards. 

The  muscle  is  closely  connected  with  the  front  of  the  capsular 
ligament.  Between  its  upper  border  and  the  coracoid  process  and 
neck  of  the  scapula  there  is  a  bursa,  which  usually  communicates 
with  the  synovial  membrane  of  the  shoulder- joint  through  an  opening 
in  the  capsule. 

Triangular  and  Quadrangular  Spaces. — When  the  long  head  of  the 
triceps  is  cut  and  displaced  a  large  triangular  space  is  seen,  which, 
as  viewed  from  behind,  is  bounded  above  by  the  teres  minor,  helow 
by  the  teres  major,  and  externally  by  the  surgical  neck  of  the 
humerus.  As  viewed  from  before,  the  subscapularis  replaces  the 
teres  minor.  When  the  long  head  of  the  triceps  is  in  position  it 
descends  in  front  of  the  teres  minor,  and  behind  the  teres  major. 
It  therefore  passes  through  the  triangular  space  and  divides  it  into 
two,  one  triangular  and  the  other  quadrangular. 

Triangular  Space. — This,  as  viewed  from  behind,  is  bounded 
above  by  the  teres  minor,  below  by  the  teres  major,  and  externally 
by  the  long  head  of  the  triceps.  As  viewed  from  before,  the  sub- 
scapularis replaces  the  teres  minor.  The  dorsalis  scapulae  artery 
passes  backwards  through  this  space,  so  long  as  the  subscapularis 
forms  one  of  its  boundaries,  but  thereafter,  and  as  seen  from  behind, 
it  only  lies  in  it  preparatory  to  piercing  the  teres  minor  and  winding 
round  the  axillary  border. 

Quadrangular  Space. — This  space,  as  viewed  from  behind,  is 
bounded  above  by  the  teres  minor,  below  by  the  teres  major,  in- 
ternally by  the  long  head  of  the  triceps,  and  externally  by  the  surgical 
neck  of  the  humerus,  the  subscapularis  replacing  the  teres  minor 
in  front.  The  structures  which  pass  through  it  are  the  circumflex 
nerve  and  posterior  circumflex  vessels.  It  is  covered  by  the 
deltoid. 

Scapular  Anastomoses  of  Arteries. — The  anastomoses  of  arteries 
upon  the  scapula  are  divided  into  two  sets — scapular  proper,  and 
acromial. 


304  A  MANUAL  OF  ANATOMY 

Scapular  Anastomoses  Proper. — The  arteries  which  take  part  in 
these  anastomoses  are  (i)  the  suprascapular  and  posterior  scapular, 
representing  the  subclavian;  and  (2)  the  dorsalis  scapulae  of  the 
subscapular,  representing  the  third  part  of  the  axillary.  The 
suprascapular  is  a  branch  of  the  thyroid  axis  of  the  first  part 
of  the  subclavian,  and  the  posterior  scapular  arises  from  the 
transverse  cervical,  which  is  also  a  branch  of  the  thyroid  axis. 
The  suprascapular  is  distributed  to  the  supraspinous  and  infra- 
spinous  fossae  and  venter,  and  so  also  is  the  posterior  scapular. 
The  subscapular  is  distributed  by  its  dorsalis  scapulae  branch  to 
the  infraspinous  fossa  and  venter.  In  the  supraspinous  fossa  the 
suprascapular  anastomoses  with  the  posterior  scapular.  In  the 
infraspinous  fossa  the  suprascapular  anastomoses  with  the  dorsalis 
scapulae,  as  does  also  the  posterior  scapular.  In  the  venter  of 
the  bone  the  ventral  branches  of  the  suprascapular  and  posterior 
scapular  anastomose  with  the  ventral  branch  of  the  dorsalis 
scapulae.  At  the  lower  angle  of  the  bone  the  posterior  scapular 
anastomoses  with  the  descending  or  teres  branch  of  the  dorsalis 
scapulae. 

Acromial  Anastomosis. — ^The  arteries  which  take  part  in  the 
acromial  anastomosis  or  rete  on  the  upper  surface  of  the  acromion 
process  are  as  follows  :  (i)  the  supra-acromial  branch  of  the  supra- 
scapular ;  (2)  branches  of  the  acromio- thoracic  artery  of  the  first 
part  of  the  axillary  ;  and  (3)  a  branch  of  the  posterior  circumflex  of 
the  third  part  of  the  axillary. 

The  importance  of  the  scapular  anastomoses  comes  into  play  after 
ligature  of  the  subclavian  artery  in  the  third  part  of  its  course. 


THE  ARTICULATIONS  OF  THE  CLAVICLE. 

Sterno  -  clavicular  Joint. — This  joint  belongs  to  the  class  di- 
arthrosis,  and  to  the  subdivision  arthrodia.  The  articular  surfaces 
are  the  inner  end  of  the  clavicle  and  the  clavicular  impression  on  the 
upper  border  of  the  presternum.  The  articular  surface  of  the 
clavicle  is  of  larger  size  than  that  on  the  presternum,  and  the  two 
are  separated  by  an  interarticular  fibro-cartilage.  The  joint  is 
surrounded  by  a  complete  capsule,  which  is  weak  above  and 
below,  but  strong  in  front  and  behind,  where  it  constitutes  the 
anterior  and  posterior  sterno-clavicular  ligaments.  Besides  these 
there  are  the  interclavicular  and  costo-clavicular  or  rhomboid 
ngaments. 

The  anterior  sterno-clavicular  ligament  is  broad,  and  its  fibres 
extend  obliquely  downwards  and  inwards  from  the  front  of  the 
clavicle  to  the  front  of  the  presternum.  The  sternal  head  of 
origin  of  the  sterno-cleido-mastoid  is  in  contact  with  it.  The 
posterior  sterno-clavicular  ligament  resembles  the  anterior,  and  is 
similarly    disposed   behind    the    joint.     The    sterno-hyoid    muscle 


Supra-acromial  Branch 
Suprascapular 
Suprascapular  Ligament  v  ' 


Supraspinous  Branch 
of  Suprascapular     '^,, 


Acromial  Rete 


Infraspinous  Branch 
of  Suprascapular 


Dorsalis  Scapulae 


Teres  Branch  of 
'Dorsalis  Scapulae 


Posterior  Scapular'-'' 


Fig    17GA. — The  Anastomoses  of  Arteries  on  the  Dorsum  and 
Acromion  Process  of  the  Scapula. 


\To /ace  page  -504. 


THE   UPPER  LIMB  305 

arises  in  part  from  it.  The  interclavicular  ligament  is  a  well- 
marked,  curved  bundle  of  fibres,  which  is  attached  at  either  side 
to  the  upper  and  back  part  of  the  inner  end  of  the  clavicle.  In 
crossing  between  the  two  bones  it  curves  downwards  to  be  attached 
to  the  interclavicular  notch  on  the  upper  border  of  the  presternum. 
The  costo-clavicular  or  rhomboid  ligament  is  a  strong,  quadrilateral 
band  of  fibres,  which  extends  from  the  upper  surface  of  the  first 
costal  cartilage  to  the  rhomboid  impression  on  the  under  surface 
of  the  clavicle,  its  direction  being  upwards,  backwards,  and 
outwards. 

The  interarticular  fibro-cartilage  is  a  nearly  circular,  flattened 
plate,  which  is  thinner  at  the  centre  and  lower  part  than  elsewhere. 
It  is  attached  superiorly  to  the  upper  and  back  part  of  the  inner  end 
of  the  clavicle,  and  inferiorly  to  the  inner  end  of  the  first  costal  car- 
tilage, where  it  inclines  slightly  outwards  to  form  part  of  a  socket 

Interclavicular 
Ligament 
Anterior  Sterno-clavicular  Ligament  I  Interarticular  Fibro-cartilage 


Costo-clavicular 

or  Rhomboid 

Ligament 


Fig.   177. — The  Sterno-Clavicular  Joints. 
(The  Left  Anterior  Sterno-clavicular  Ligament  has  been  removed.) 

for  the  lower  portion  of  the  inner  end  of  the  clavicle.  Its  circum- 
ference is  connected  with  the  fibrous  capsule  of  the  joint.  The  plate 
sometimes  presents  a  perforation  at  its  centre. 

There  are  two  synovial  membranes  at  this  joint,  one  on  either 
side  of  the  interarticular  fibro-cartilage.  When  the  latter  is 
perforated  these  are  continuous  with  each  other. 

Arterial  Supply. — ^The  suprasternal  branch  of  the  suprascapular, 
and  the  internal  mammary. 

Nerve-supply. — The  suprasternal  branch  of  the  cervical  plexus. 

Movements. — These  take  place  in  an  upward,  downward,  forward,  and  back- 
ward direction.  There  is  also  circumduction.  In  the  upward  and  downward 
movements  the  clavicle  moves  on  the  fibro-cartilage,  and  the  forward  and 
backward  movements  take  place  between  the  fibro-cartilage  and  the  pre- 
sternum. In  the  downward  movement  of  the  bone  the  interarticular  ligament 
is  put  upon  the  stretch,  and  the  upward  movement  is  limited  by  the  costo- 
clavicular ligament. 

Acromio-clavicular  Joint.  —This  belongs  to  the  class  diarthrosis, 

and  to  the  subdivision  arthrodia.  The  articular  surfaces  are  the 
outer  end  of  the  clavicle  and  the  facet  on  the  acromion  process. 

20 


3o6 


A   MANUAL  OF  ANATOMY 


These  surfaces  are  sometimes  partially  separated  by  an  inter- 
articular  fibro-cartilage,  and  the  joint  is  surrounded  by  a  complete 
capsule,  which  forms  the  superior  and  inferior  ligaments. 

The  superior  and  inferior  acromio-clavicular  ligaments  extend 
between  the  contiguous  margins  of  the  bones  on  their  upper  and 
under  surfaces,  the  former  being  strengthened  by  aponeurotic 
fibres  from  the  trapezius  and  deltoid.  The  interarticular  fibro- 
cartilage,  when  present,  is  limited  to  the  upper  part  of  the  joint, 
where  it  is  attached  to  the  superior  ligament.  It  may  divide 
the  joint  into  two  synovial  compartments,  but  there  is  usually 
only  one. 

The  coraco-elavicular  ligament,  which  is  to  be  regarded  as  acces- 
sory to  this  joint,  connects  the  clavicle  with  the  coracoid  process, 

Capsule  of  Acromio-clavicular  Joint         Coraco-acromial  Ligament 


Trapezoid  Ligament 
Conoid  Ligament 


Long  Head  of  Biceps 


Glenoid  Ligament 


Capsular  Ligament 
(cut) 


Fig.  187. — The  Rigijt  Glenoid  Cavity,  and  the  Adjacent  Ligaments. 


and  is  composed  of  two  parts — conoid  and  trapezoid.  The  conoid 
ligament,  internal  and  posterior  in  position,  is  attached  below  by 
its  apex  to  an  impression  at  the  back  part  of  the  antero-internal 
border  of  the  coracoid  process,  and  above  by  its  base  to  the  conoid 
tubercle  of  the  clavicle,  its  direction  being  upwards  and  backwards. 
The  trapezoid  ligament,  external  and  anterior  in  position,  is  some- 
what quadrilateral.  It  is  attached  below  to  the  trapezoid  ridge  on 
the  back  part  of  the  upper  surface  of  the  coracoid  process,  and 
above  to  the  trapezoid  ridge  on  the  under  surface  of  the  clavicle,  its 
direction  being  upwards,  backwards,  and  outwards.  Between  the 
two  ligaments  there  is  a  slight  interval,  in  which  there  may  be  a 
bursa. 

Arterial  Supply. — The  suprascapular  and  acromio-thoracic  arteries. 

Nerve-supply. — The  suprascapular  and  circumflex  nerves. 


THE  UPPER  LIMB  307 

Movements. — The  movements  at  this  joint  are  limited,  and  are  principally 
of  a  gliding  nature  in  an  upward  and  downward,  and  forward  and  backward, 
direction. 

The  Ligaments  of  the  Scapula. 

These  are  three  in  number — suprascapular,  coraco-acromial,  and 
spino-glenoid. 

The  suprascapular  or  transverse  ligament  extends  from  the  upper 
border  of  the  scapula,  internal  to  the  suprascapular  notch,  to  the  root 
of  the  coracoid  process.  It  is  thin  and  flat,  and  it  bridges  over  the 
notch,  which  it  converts  into  a  foramen.  It  usually  gives  origin  to 
some  fibres  of  the  posterior  belly  of  the  omo-hyoid,  and  the  supra- 
scapular nerve  passes  backwards  beneath  it  and  the  suprascapular 
artery  over  it.     This  ligament  sometimes  undergoes  ossification. 

The  coraco-acromial  ligament,  which  is  triangular,  is  attached  by 
its  apex  to  the  tip  of  the  acromion  process,  and  by  its  base  to  the 
postero-external  border  of  the  coracoid  process.  Its  superior 
surface  is  covered  by  the  deltoid,  and  the  inferior  surface  overhangs 
the  shoulder- joint,  the  subacromial  bursa  intervening.  The  acro- 
mion process,  coraco-acromial  ligament,  and  coracoid  process  form 
the  coraco-acromial  arch,  within  which  the  head  of  the  humerus 
fits  when  the  arm  is  abducted.  The  arch  therefore  forms  an 
auxiliary  socket  for  the  head  of  the  bone. 

The  spino-glenoid  ligament  consists  of  a  few  fibres  which  extend 
from  the  outer  border  of  the  spine  to  the  adjacent  part  of  the  margin 
of  the  glenoid  cavity.  It  arches  over  the  suprascapular  artery  and 
nerve  as  they  pass  through  the  great  scapular  notch  on  their  way 
to  the  infraspinous  fossa. 


THE  ARM. 

Landmarks.— The  front  of  the  brachial  region  presents  a  well- 
marked  elongated  prominence,  due  to  the  biceps,  which  reaches 
from  the  anterior  fold  of  the  axilla  to  near  the  elbow.  Internal  to 
this  prominence,  above,  is  another  swelling  caused  by  the  coraco- 
brachiahs.  On  either  side  of  the  bicipital  prominence  is  a  groove, 
that  on  the  outer  side  indicating  the  position  of  the  cephalic  vein, 
and  that  on  the  inner  side  the  position  of  the  basilic  vein,  brachial 
artery,  and  median  nerve.  External  to  the  bicipital  prominence, 
for  a  short  distance  above  the  elbow,  is  the  prominence  formed  by 
the  brachio-radialis  and  extensor  carpi  radialis  longior.  At  the 
elbow  the  internal  and  external  epicondyles  of  the  humerus  and 
the  olecranon  process  of  the  ulna  are  to  be  noted.  The  internal 
epicondyle  forms  a  very  distinct  projection,  having  an  inclination 
backwards,  and  behind  it,  close  to  the  olecranon,  is  the  ulnar  nerve. 
The  external  epicondyle,  which  is  not  well  marked,  may  be  felt  in 
semiflexion  of  the  joint.  The  olecranon  process  can  easily  be  felt 
at  the  back.     In  extension  of  the  joint  the  summit  of  the  olecranon 

20 — 2 


3o8 


A  MANUAL  OF  ANATOMY 


is  on  the  same  line  with  the  two  epicondyles.  When  the  arm  and 
forearm  are  placed  in  the  position  of  a  right  angle  the  summit  of 
the  olecranon  falls  below  a  line  connecting  the  epicondyles.  In 
extreme  flexion  of  the  elbow  the  summit  of  the  olecranon  is  anterior 
to  a  line  connecting  the  epicondyles.     The  posterior  surface  of  the 


Supraclavicular 

Anterior  Branches  of  Lateral  Cutaneous 
Supra-acromial 


Suprasternal 


Cutaneous  Branch  of. 
Circumflex 


Upper  External  Cutaneous 
of  Musculo-spiral 


Branch  of  Radial- 


.  Anterior  Cutaneous 


~  "-  -Twig  of  Interna!  Cutaneous 
~,lntercosto-humeral 


.Anterior  Branch  of  Internal  Cutaneous 
.  Posterior  Branch  of  Internal  Cutaneous 


Anterior  Branch  of  Musculo-cutaneous 


Twig  of  Ulnar 
(occasional) 


Palmar  Cutaneous  of  Ulnar 
Palmar  Cutaneous  of  Median 


Fig.  179. — Diagram  of  the  Cutaneous  Nerves  of  the  Upper  Limb 
(Anterior  Aspect). 

olecranon  is  covered  by  a  subcutaneous  bursa.  The  head  of  the 
radius  can  be  felt,  in  extension  of  the  joint,  at  the  bottom  of  a  de- 
pression situated  at  the  outer  and  back  part,  where  it  lies  just  below 
the  external  epicondyle.  It  is  most  readily  felt  when  the  forearm 
is ;  alternately  pronated  and  supinated.  In  front  of  the  elbow  there 
is  a  slight  hollow  indicating  the  position  of  the  anticubital  fossa,  and 


THE   UPPER  LIMB 


309 


Supra-acromial 


in  this  region  the  outhnes  of  the  median  basilic  and  median  cephaHc 
veins  may  be  visible,  especially  the  former.  On  the  back  of  the 
forearm  the  posterior  border  of  the  ulna  can  readily  be  felt.  It 
leads  superiorly  to  the  subcutaneous  bursa  on  the  back  of  the  ole- 
cranon, and  interiorly  it  conducts  to  the  styloid  process  of  the  bone, 
which  is  situated  mainly  on  its  posterior  aspect.  On  the  outer  side 
of  the  lower  end  of  the  radius 
its  styloid  process  can  easily  be 
felt,  which  projects  lower  down 
than  that  of  the  ulna,  and  in 
front  of  it  is  the  radial  artery. 
On  the  back  of  the  radius,  about 
its  centre,  is  the  radial  tubercle, 
which  bounds  externally  the 
groove  for  the  tendon  of  the 
extensor  longus  pollicis. 

Olecranon  Bursa. — This  bursa 
is  situated  subcutaneously  over 
the  posterior  triangular  surface 
of  the  olecranon  process  of  the 
ulna. 

Cutaneous  Nerves. — The  inter- 
costo  -  humeral  nerve,  having 
crossed  the  axillary  space, 
ramifies  in  the  integument  of 
the  inner  and  back  part  of  the 
arm  over  its  upper  half.  It 
may  be  accompanied  by  an  off- 
set of  the  posterior  branch  of  the 
lateral  cutaneous  of  the  third 
intercostal. 

The  lesser  internal  cutaneous 
or  nerve  of  Wrisberg  is  dis- 
tributed to  the  integument  of 
the  inner  side  of  the  arm,  as 
low  as  the  interval  between 
the  internal  epicondyle  and 
olecranon. 

The  internal  cutaneous  nerve 
furnishes  one  or  more  branches.    Fig.  180.— Diagram  of  the  Cutaneous 
which,   piercing  the  deep  fascia  Nerves     of     the     Upper     Limb 

close     to     the    axilla,     are     dis-  (Posterior  Aspect). 

tributed  to  the  integument  over 

the  biceps.  The  nerve  itself  pierces  the  deep  fascia  a  little  below 
the  centre  of  the  arm,  and  then  divides  into  an  anterior  and 
a  posterior  branch.  The  anterior  branch  descends  behind  the 
median  basilic  vein,  giving  one  or  two  twigs  over  it,  and  it 
is  distributed  to  the  integument  of  the  anterior  aspect  of  the 
inner    side    of   the    forearm.     The   -posterior  branch   passes  down- 


Cutaneous  Branch  of 

Circumflex 

Interna!  Cutaneous  of 

Musculospiral 

_  _  -  'Intercosto-humeral 


-Lower  External  Cutaneous 
of  Musculo-spiral 

Nerve  of  Wrisberg 


--  Posterior  Branch  of  Internal 
Cutaneous 

— Posterior  Branch  of  Musculo- 
cutaneous 


^•Radial 


Dorsal  Branch  of  Ulnar 


.3IO  A  MANUAL  OF  ANATOMY 

wards  and  inwards  on  the  inner  side  of  the  basihc  vein,  and 
over  the  internal  epicondyle,  after  which  it  turns  backwards 
to  supply  the  integument  over  the  back  of  the  inner  side  of  the 
forearm. 

The  internal  cutaneous  of  the  museulo-spiral  is  distributed  to 
the  integument  of  the  back  of  the  arm,  almost  as  low  as  the 
olecranon. 

The  external  cutaneous  branches  of  the  museulo-spiral  are  two  in 
number — upper  and  lower.  They  leave  the  main  trunk  towards  the 
lower  end  of  the  spiral  groove,  just  before  the  nerve  passes  through 
the  external  intermuscular  septum,  and  the  two  branches  pierce 
the  deep  fascia  about  i  inch  apart.  The  tipper  branch,  of  small 
size,  descends  with  the"  cephalic  vein  to  the  front  of  the  elbow, 
giving  branches  to  the  integument  of  the  outer  and  anterior 
aspects  of  the  arm  in  its  lower  half.  The  lower  branch,  of  larger 
size,  descends  behind  the  external  epicondyle  into  the  forearm, 
where  it  is  distributed  to  the  integument  on  the  posterior  aspect 
of  the  outer  side  as  low  as  the  wrist. 

The  cutaneous  branch  of  the  musculo -cutaneous  pierces  the 
deep  fascia  on  the  outer  side  of  the  biceps  a  little  above  the 
elbow.  It  descends  behind  the  median  cephalic  vein,  giving  one 
or  two  twigs  over  it,  and  then  it  divides  into  two  branches. 
One  supplies  the  integument  on  the  anterior  aspect  of  the  outer 
side  of  the  forearm,  and  the  other  gives  branches  to  the  integument 
on  the  posterior  aspect. 

The  cutaneous  branch  of  the  ulnar,  which  arises  about  the 
centre  of  the  forearm,  pierces  the  deep  fascia,  and  has  a  limited 
distribution  to  the  integument  just  below  the  centre,  internal  to 
the  median  line.     This  branch  is  inconstant. 

Superficial  Veins. — There  are  four  principal  superficial  veins  in 
the  forearm,  namely,  the  median,  radial,  anterior  ulnar,  and 
posterior  ulnar. 

The  median  vein  is  formed  by  the  union  of  a  few  radicles  which 
originate  in  the  venous  plexus  in  front  of  the  wrist,  and  its  course 
is  upwards  in  front  of  the  forearm.  As  it  ascends  it  takes  up 
several  veins,  and  often  receives  a  large  tributary  from  the  back 
of  the  limb.  It  is  also  in  free  communication  with  the  radial  and 
anterior  ulnar  veins.  On  arriving  at  the  hollow  in  front  of  the 
elbow  it  receives  a  short  but  large  branch,  called  the  deep  median 
vein,  which  establishes  a  communication  between  it  and  the  deep 
venae  comites.  Thereafter  it  divides  into  median  cephalic  and 
median  basilic,  which  diverge  from  each  other  as  they  ascend, 
somewhat  like  the  capital  letter  V.  The  median  cephalic  vein,  the 
smaller  of  the  two,  passes  upwards  and  outwards  in  the  interval 
between  the  biceps  and  brachio-radialis,  having  the  cutaneous 
part  of  the  musculo-cutaneous  nerve  behind,  and  a  few  of  its 
twigs  over  it.  A  little  above  the  external  epicondyle  it  receives 
the  radial  vein,  the  resulting  trunk  being  called  the  cephalic  vein. 
The  median  basilic  vein,  the  larger  of  the  two,  passes  inwards  and 


THE   UPPER  LIMB 


3" 


Pectoralis  Major 

Axillary  Vein 
Cephalic  Vein 
Pectoralis  Minor^^ 


ViL.^ 


Cephalic  Vein  --'' 

Median  Cephalic  Vein 

Radial  Vein-- 

Superficial  Median  Vein  '■' 


__  Basilic  Vein 

_, Internal  Epic 
, Median  Basilic  Vein 

__  Posterior  Ulnar  Vein 
Deep  Median  Vein 

[■^Anterior  Ulnar  \'ein 


.  Palmar  Venous  Arch 


Fig.    i8i. — The  Superficial  Veins  of  the   Upper  Limb 
(Anterior  View). 


312  A  MANUAL  OF  ANATOMY 

upwards,  crossing  the  bicipital  fascia,  which  separates  it  from  the 
brachial  artery,  and  the  anterior  branch  of  the  internal  cutaneous 
nerve  descends  behind  it,  a  few  of  its  twigs  passing  over  it.  Just 
above  the  internal  epicondyle  it  receives  the  anterior  and  posterior 
ulnar  veins,  either  separately  or  as  a  common  trunk,  and  the  resulting 
vessel  is  called  the  basilic  vein. 

The  radial  vein  commences  in  the  outer  part  of  the  plexus 
on  the  back  of  the  hand,  and  it  ascends  at  first  on  the  back  of 
the  outer  side  of  the  forearm,  but  gradually  inclines  to  its  outer 
aspect.  A  little  above  the  external  epicondyle  it  joins  the  median 
cephalic  vein. 

The  anterior  ulnar  vein  commences  on  the  inner  aspect  of  the 
front  of  the  wrist,  and  it  ascends  in  front  of  the  inner  side  of  the  fore- 
arm, to  end  either  in  the  median  basilic  or  by  joining  the  posterior 
ulnar  vein. 

The  posterior  ulnar  vein,  of  large  size,  commences  in  the  inner 
part  of  the  plexus  on  the  back  of  the  hand,  and  it  ascends  along  the 
back  of  the  inner  side  of  the  forearm  to  join  the  median  basilic, 
either  separately  or  having  previously  taken  up  the  anterior  ulnar 
vein. 

The  principal  superficial  veins  of  the  brachial  region  are  the 
cephalic  and  the  basilic. 

The  cephalic  vein  is  formed  by  the  union  of  the  median  cephalic 
and  the  radial  a  little  above  the  external  epicondyle.  It  then 
ascends,  lying  at  first  in  the  groove  along  the  outer  border  of  the 
biceps,  and  then  between  the  pectoralis  major  and  deltoid.  There- 
after it  crosses  the  first  part  of  the  axillary  artery,  and,  piercing  the 
costo-coracoid  membrane  and  axillary  sheath,  opens  into  the 
axillary  vein  above  the  pectoralis  minor. 

The  basilic  vein  is  formed  by  the  union  of  the  median  basilic, 
anterior  ulnar,  and  posterior  ulnar,  just  above  the  internal  epicon- 
dyle. It  then  ascends  in  the  groove  along  the  inner  border  of  the 
biceps,  lying  inside  the  line  of  the  brachial  artery.  In  the  lower 
half  of  the  arm  it  is  superficial  to  the  deep  fascia,  but  about  the 
centre  it  pierces  it,  and  becomes  the  axillary  vein  at  the  lower  border 
of  the  tendon  of  the  teres  major.  In  contact  with  the  basUic  vein, 
just  above  the  internal  epicondyle,  there  are  one  or  two  Ijnnphatic 
glands. 

Lymphatics. — ^The  lymphatics  of  the  upper  limb  are  arranged  in 
two  sets — superficial  and  deep. 

Superficial  Lymphatics. — These  commence  in  networks  in  the 
tissues  around  the  nails,  whence  they  pass  along  the  sides  of  the 
fingers  on  their  palmar  and  dorsal  aspects,  receiving  vessels  from 
the  front  and  back  of  each  finger.  The  palmar  Ijnnphatics  end  in 
a  palmar  network,  and  the  dorsal  in  a  dorsal  network.  The  vessels 
proceeding  from  the  palmar  network  pass  over  the  wrist  into  the 
forearm,  and  ascend  in  three  sets  which  accompany  the  radial, 
median,  and  ulnar  veins.  In  this  course  the  outer  and  inner  lym- 
phatics are  reinforced  at  intervals  by  vessels  which  come  round 


THE   UPPER  LIMB 


313 


from  the  back  of  the  forearm,  and  which  originate  below  in  the 
dorsal  network.  The  lymphatics  of  the  inner  set  become  the 
afferent  vessels  of  the  glands  above  the 
internal  epicondyle,  and  the  efferent 
vessels  of  these  glands  ascend  along  the 
inner  border  of  the  biceps,  in  company 
with  the  basilic  vein,  to  become  the 
afferent  vessels  of  the  external  group  of 
axillary  glands.  The  lymphatics  of  the 
middle  and  outer  sets  pass  upwards  along 
the  outer  border  of  the  biceps,  and  most 
of  them  gradually  cross  inwards  over 
the  muscle  to  end  in  the  external  axillary 
glands.  Some  of  them,  however,  ac- 
company the  cephalic  vein,  and  end  in 
the  infraclavicular  group  of  glands. 
The  superficial  lymphatics  from  the 
integument  over  the  deltoid  also  end 
in  the  infraclavicular  glands. 

Deep  Lymphatics. — These  accompany 
the  bloodvessels.  In  the  forearm  there 
are  four  sets,  accompanying  the  radial, 
ulnar,  anterior  interosseous,  and  pos- 
terior interosseous  arteries.  In  the  arm 
these  four  sets  form  one  group,  the 
vessels  of  which  accompany  the  brachial 
artery  and  terminate  in  the  external 
axillary  glands. 

The  lymphatic  glands  are  arranged 
in  two  sets  —  superficial  and  deep. 
There  are  no  superficial  glands  in  the 
hand  or  forearm.  Sometimes  there  are 
one  or  two  connected  with  the  superficial 
lymphatics  at  the  bend  of  the  elbow, 
and  there  are  always  one  or  two  just 
above  the  internal  epicondyle,  in  contact 
with  the  basilic  vein.  A  few  deep 
lymphatic  glands  are  sometimes  met 
with  along  the  course  of  the  deep  lym- 
phatics which  accompany  the  arteries  of 
the  forearm,  and  a  few  are  placed  along 
the    brachial     artery.      The    principal 

deep  glands,  however  are  those  in  the  ^^^  ,82.-The  Superficial 
axillary  space,  which  have  been  already  Lymphatics  of  the  Upper 
described.  Limu  (Anterior  View). 


314  A  MANUAL  OF  ANATOMY 


FRONT  OF  THE  BRACHIAL  REGION. 

Deep  Fascia. — The  deep  fascia  or  aponeurosis  forms  a  continuous 
investment  to  the  arm,  its  fibres  being  principally  disposed  trans- 
versely, but  others  run  more  or  less  longitudinally.  It  is  continuous 
above  with  the  axillary  fascia  and  the  fascial  investments  of  the 
pectoralis  major  and  deltoid,  the  tendons  of  which  give  expansions 
to  it.  It  is  thin  over  the  biceps,  and  somewhat  thicker  over  the 
triceps,  but  it  becomes  specially  strong  in  the  region  of  the  elbow, 
where  it  is  attached  to  the  epicondyles  of  the  humerus  and  olecranon 
process  of  the  ulna.  In  front  of  the  elbow  it  receives  a  considerable 
accession  of  fibres  from  the  bicipital  or  semilunar  fascia.  At  about 
the  centre  of  the  arm,  on  its  inner  aspect,  it  presents  an  opening  for 
the  passage  of  the  basilic  vein.  The  deep  fascia  is  connected  with 
the  lower  part  of  the  humerus  on  either  side  by  two  deep  processes, 
called  intermuscular  septa.  The  external  septum  is  attached  to  the 
external  epicondyle,  and  external  supracondylar  ridge  as  high  as  a 
point  posterior  to  the  lower  part  of  the  tendon  of  insertion  of  the 
deltoid,  with  which  it  is  connected.  It  gives  origin  posteriorly  to 
fibres  of  the  inner  head  of  the  triceps,  below  where  it  is  pierced  by  the 
musculo-spiral  nerve,  and  above  that  point  to  fibres  of  the  external 
head.  Anteriorly,  from  above  downwards,  it  gives  origin  to  a  small 
part  of  the  brachialis  anticus,  brachio-radialis,  and  extensor  carpi 
radialis  longior.  It  is  pierced  from  behind  forwards  by  the  musculo- 
spiral  nerve  and  the  anterior  terminal  branch  of  the  superior  profunda 
artery,  the  posterior  terminal  branch  descending  behind  it.  The 
internal  septum  is  stronger  than  the  external,  and  is  attached  to  the 
internal  epicondyle,  and  internal  supracondylar  ridge  as  high  as  a 
point  behind  the  insertion  of  the  coraco-brachialis.  It  gives  origin 
anteriorly  to  the  brachialis  anticus,  and  posteriorly  to  the  inner  head 
of  the  triceps.  It  is  pierced,  at  its  upper  part,  from  before  back- 
wards by  the  ulnar  nerve  and  inferior  profunda  artery,  and,  a  little 
above  the  elbow,  by  the  posterior  branch  of  the  anastomotica  magna 
artery.  Connected  with  the  internal  septum  there  is  a  fibrous 
band,  known  as  the  internal  brachial  ligament  (Struthers),  which 
extends  from  the  humerus  below  the  tendon  of  insertion  of  the  teres 
major  to  the  internal  epicondyle.  The  two  intermuscular  septa 
divide  the  lower  half  of  the  arm  into  two  compartments — anterior 
and  posterior.  The  anterior  compartment  contains  the  biceps, 
brachialis  anticus,  brachio-radialis,  extensor  carpi  radialis  longior, 
basilic  vein,  brachial  vessels,  median  nerve,  ulnar  nerve  for  a  short 
distance  above,  internal  cutaneous  nerve,  nerve  of  Wrisberg,  and 
musculo-spiral  nerve  after  it  has  pierced  the  external  septum.  The 
posterior  compartment  contains  the  triceps  and  a  small  part  of  the 
musculo-spiral  nerve. 

Coraco-brachialis — Origin. — (i)  The  tip  of  the  coracoid  process  of 
the  scapula ;  and  (2)  the  inner  aspect  of  the  tendon  of  the  short  head 
of  the  biceps  for  3  inches  or  more. 


THE   UPPER  LIMB  3^5 

Insertion. — The  inner  side  of  the  humerus  at  its  centre  for  about 
an  inch  and  a  half.  Some  of  the  upper  fibres  are  inserted  into  a 
fibrous  band,  which  ascends  in  front  of  the  tendons  of  the  latissimus 
dorsi  and  teres  major  to  be  attached  to  the  humerus  below  the  small 
tuberosity. 

Nerve-supply.— The  musculo-cutaneous  nerve,  by  a  branch  which 
derives  its  fibres  from  the  seventh  cervical. 

The  muscle  is  directed  downwards,  outwards,  and  slightly  back- 
wards. 

Action.— To  adduct  and  flex  the  humerus.  It  also  braces  the 
head  of  the  bone  against  the  glenoid  cavity. 

The  muscle  is  pierced  by  the  musculo-cutaneous  nerve. 

Biceps  Flexor  Cubiti— Ongm. — (i)  The  short  head  arises  from  the 
tip  of  the  coracoid  process  of  the  scapula  in  association  with  the 
coraco-brachialis  ;  (2)  the  long  head  arises  from  the  supraglenoid 
tubercle  of  the  scapula  by  a  rounded  tendon,  which  lies  within  the 
capsular  ligament  of  the  shoulder-joint,  and  is  continuous  on  either 
side  with  the  glenoid  ligament. 

Insertion. — (i)  The  posterior  rough  portion  of  the  bicipital 
tuberosity  of  the  radius,  being  separated  from  the  anterior  smooth 
portion  by  a  bursa  ;  and  (2)  the  deep  fascia  covering  the  muscles 
arising  from  the  internal  epicondyle  of  the  humerus  by  means  of  the 
bicipital  or  semilunar  fascia. 

The  short  head  arises  by  a  short  tendon,  and  the  tendon  of  the  long 
head  is  about  4  inches  in  length.  This  latter  tendon  arches  over  the 
head  of  the  humerus,  and  leaves  the  interior  of  the  joint  by  entering 
the  bicipital  groove,  beneath  the  transverse  humeral  ligament. 
Within  the  joint  it  is  invested  by  a  tubular  sheath  formed  by  the 
synovial  membrane,  which  accompanies  it  for  a  short  distance  in  the 
bicipital  groove,  and  is  then  reflected  upwards  to  become  continuous 
with  the  synovial  lining  of  the  capsular  ligament.  After  leaving  the 
bicipital  groove  the  tendon  is  replaced  by  a  conical  bundle  of  fleshy 
fibres,  and  these  join  the  fibres  derived  from  the  short  head  about  the 
centre  of  the  arm,  giving  rise  to  an  elongated,  oval,  fleshy  belly. 
At  the  level  of  the  epicondyles  of  the  humerus  the  belly  gives 
place  to  the  strong  tendon  of  insertion,  which  sinks  into  the  anti- 
cubital  space,  and  undergoes  a  quarter  of  a  turn  before  reaching  its 
insertion.  From  the  inner  side  of  the  tendon,  towards  its  upper  part, 
a  strong  band  of  fibres  is  given  off,  which  passes  to  the  deep  fascia 
covering  the  muscles  arising  from  the  internal  epicondyle.  It  is 
called  the  bicipital  or  semilunar  fascia,  and  it  passes  over  the  brachial 
artery,  whilst  the  median  basilic  vein  lies  upon  it. 

Nerve-supply. — The  musculo-cutaneous  nerve,  which  is  a  branch 
of  the  outer  cord  of  the  brachial  plexus,  its  fibres  being  derived  from 
the  fifth,  sixth,  and  seventh  cervical. 

Action.— (i)  To  flex  the  elbow-joint ;  (2)  to  supinate  the  forearm  ; 
(3)  by  its  short  head  to  adduct  and  flex  the  arm,  and  (4)  by  its  long 
head  to  raise  the  arm. 

Internal  to  the  muscle  in  the  upper  half  is  the  coraco-brachialis. 


3i6 


A  MANUAL  OF  ANATOMY 


and  in  the  lower  half  the  brachial  artery  and  median  nerve.  Ex- 
ternal to  it  is  the  cephalic  vein.  The  biceps  sometimes  has  a  third 
head,  which  usually  arises  from  the  inner  side  of  the  humerus 
at  or  near  the  insertion   of  the  coraco-brachialis.      As  a  rule,  it 


Deltoid. 

Biceps - 
Coraco-brachialis  J 


Musculo-cutaneous  Nerve.- 


Brachialis  Amicus - 


Musculo-spiral  Nerve 

Brachio-radialis 

Radial  Nerve  — 
Posterior  Interosseous  Nerve 

Supinator  Radii  Brevis 
Ulnar  Artery 

Radial  Artery 


Latissimus  Dorsi 
.Teres  Major 

Ulnar  Collateral  Nerve 

of  Krause 
Ulnar  Nerve 
Long  Head  of  Triceps 
Brachial  Artery 
Median  Nerve 
Inner  Head  of  Triceps 


Internal  Intermuscular 
Septum 


Internal  Epicondyle 


Flexor  Carpi  Radialis 

Palmaris  Longus 
Fle.xor  Carpi  Ulnaris 


Pronator  Radii  Teres 


Fig.   183. — Dissection  of  the  Right  Brachial  Region,  and 
Bend  of  the  Elbow. 


is  external  to  ^the  brachial  artery,   but  sometimes  it  crosses  the 
vessel. 

Brachialis  Anticus — Origin. — (i)  The  lower  half  of  the  front  of 
the  humerus  ;  (2)  the  front  of  the  internal  intermuscular  septum  over 
the  whole  of  its  extent ;  and  (3)  the  front  of  the  external  intermus- 
cular septum  for  a  short  distance  above. 


THE   UPPER  LIMB  317 

Superiorly  the  muscle  sends  a  pointed  projection  upwards  on 
either  side  of  the  lower  part  of  the  insertion  of  the  deltoid. 

Insertion. — ^The  inner  part  of  the  rough  triangular  surface  on  the 
front  of  the  coronoid  process  of  the  ulna. 

Nerve-supply. — (i)  The  musculo-cutaneous  nerve,  and  (2)  a  twig 
from  the  musculo-spiral  nerve. 

Action. — ^The  muscle  is  a  direct  flexor  of  the  elbow- joint. 

Brachial  Artery. — The  brachial  artery  is  the  continuation  of  the 
axillary,  and  it  extends  from  the  lower  border  of  the  teres  major  to 
a  point  just  below  the  bend  of  the  elbow,  where  it  divides  opposite 
the  upper  part  of  the  neck  of  the  radius  into  the  radial  and  ulnar 
arteries.  It  is  at  first  internal  to  the  humerus,  but  gradually 
inclines  to  the  front  of  the  bone,  and  at  the  elbow  it  is  equally 
distant  from  the  two  epicondyles.  The  course  of  the  vessel  is 
indicated  by  a  line  drawn  from  a  point  midway  between  the  anterior 
and  posterior  folds  of  the  axilla  at  the  humerus  to  a  point  midway 
between  the  epicondyles  of  the  bone.  The  artery  is  accompanied 
b}^  two  venae  comites,  one  on  either  side,  which  communicate  with 
each  other  over  the  vessel  at  frequent  intervals.  It  is  for  the  most 
part  superficial,  being  only  slightly  overlapped  by  the  coraco- 
brachialis  and  biceps.  At  the  bend  of  the  elbow,  however,  it  sinks 
deeply  under  cover  of  the  semilunar  fascia,  and  lies  in  the  anti- 
cubital  space. 

Relations — Superficial. — Skin,  superficial  and  deep  fasciae,  median 
nerve  about  the  centre  of  the  arm,  semilunar  fascia  of  the  biceps,  and, 
superficial  to  this,  the  median  basilic  vein.  Deep. — ^The  long  head 
of  the  triceps,  with  the  intervention  of  the  musculo-spiral  nerve  and 
superior  profunda  artery,  inner  head  of  the  triceps,  insertion  of  the 
coraco-brachialis,  and  brachialis  anticus.  External. — The  coraco- 
brachialis  and  biceps,  both  of  which  slightly  overlap  the  vessel, 
external  vena  comes,  and  the  median  nerve  in  the  upper  half  of  the 
arm.  Internal. — ^The  internal  vena  comes,  internal  cutaneous  nerve 
(which  may  be  slightly  over  the  vessel)  as  low  as  the  centre  of  the 
arm,  ulnar  nerve  also  as  low  as  the  centre,  median  nerve  in  the  lower 
third,  and  basilic  vein,  which  is  superficial  to  the  deep  fascia  in  the 
lower  half,  but  beneath  it  in  the  upper  half.  The  nerve  most 
intimately  related  to  the  artery  is  the  median,  which  lies  on  its 
outer  side  in  the  upper  half  of  the  arm,  in  front  of  it  for  a  little  at  the 
centre,  and  on  its  inner  side  in  the  lower  third. 

Branches. — The  vessel  gives  off  from  its  outer  side  a  series  of 
branches  which  are  distributed  to  the  muscles  and  integument 
of  the  front  of  the  arm.  The  named  branches  arise  from  the 
inner  and  back  part  of  the  trunk.  They  are  called  superior 
profunda,  inferior  profunda,  nutrient,  and  anastomotica  magna. 

The  superior  profunda  artery  is  a  large  vessel  which  arises 
from  the  l>ack  of  tlie  brachial  near  its  commencement.  It  passes 
downwards  and  backwards  with  the  musculo-sj)iral  nerve  between 
the  long  and  inner  heads  of  the  triceps,  and  it  then  winds  round  the 
back  of  the  humerus,  lying  with  the  nerve  in  the  si)iral  groove, 


3i8  A   MANUAL  OF  ANATOMY 

between  the  outer  and  inner  heads  of  that  muscle.  Towards  the 
lower  end  of  the  groove  it  divides  into  two  terminal  branches — 
anterior  and  posterior.  The  anterior  branch  accompanies  the 
musculo-spiral  nerve  through  the  external  intermuscular  septum, 
and  then  descends  between  the  brachio-radialis  and  brachialis 
anticus  to  anastomose  with  the  radial  recurrent  artery.  The  pos- 
terior branch  descends  behind  the  external  intermuscular  septum, 
and  anastomoses  behind  the  external  epicondyle  with  the  posterior 
interosseous  recurrent,  and  across  the  back  of  the  humerus  above 
the  olecranon  fossa  with  the  anastomotica  magna.  Besides  the 
two  terminal  branches  the  superior  profunda  gives  off  the  follow- 
ing offsets  :  muscular  to  the  triceps  ;  an  ascending  branch,  which 
passes  upwards  between  the  long  and  outer  heads  of  the  triceps 
to  anastomose  with  a  branch  of  the  posterior  circumflex ;  and  a 
nutrient  branch,  which  enters  a  foramen  on  the  back  of  the  humerus. 

The  superior  profunda  may  arise  from  the  third  part  of  the 
axillary,  and  it  may  give  off  the  posterior  circumflex. 

The  inferior  profunda  artery  arises  from  the  brachial  about  the 
centre  of  the  arm,  or  sometimes  from  the  superior  profunda.  It 
accompanies  the  ulnar  nerve  through  the  internal  intermuscular 
septum,  and  then  descends  with  it  on  the  inner  head  of  the  triceps 
to  the  back  of  the  internal  epicondyle,  where  it  anastomoses  with 
the  anastomotica  magna  and  posterior  ulnar  recurrent  arteries.  In 
its  course  it  gives  muscular  offsets  to  the  triceps. 

The  nutrient  or  medullary  artery  arises  from  the  brachial  opposite 
the  lower  border  of  the  insertion  of  the  coraco-brachialis,  or  it  may 
come  off  from  the  inferior  profunda.  Its  course  is  downwards, 
and  it  enters  the  medullary  foramen  of  the  bone  to  be  distributed 
to  its  interior. 

The  anastomotica  magna  artery  arises  about  2  inches  above  the 
elbow.  It  passes  inwards  on  the  brachialis  anticus,  and  divides  into 
two  branches — a  small  anterior  and  large  posterior.  The  anterior 
branch  descends  beneath  the  pronator  radii  teres,  and  anastomoses 
with  the  anterior  ulnar  recurrent  artery. .  The  posterior  branch 
pierces  the  internal  intermuscular  septum,  and  then  passes  outwards 
beneath  the  triceps,  resting  upon  the  back  of  the  humerus  above  the 
olecranon  fossa,  where  it  forms  an  arch  with  the  posterior  branch  of 
the  superior  profunda  artery.  It  gives  a  branch  to  the  back  of  the 
internal  epicondyle,  which  anastomoses  with  the  inferior  profunda 
and  posterior  ulnar  recurrent  arteries. 

Varieties. — i.  The  brachial  artery  may  divide  above  the  normal  level.  In 
most  cases  the  vessel  given  oflE  earher  than  usual  is  the  radial  ;  more  rarely  it 
is  the  ulnar,  and  in  these  cases  the  interosseous  trunk  arises  from  the  radial  ; 
still  more  rarely  the  premature  branch  is  the  interosseous  trunk,  or  a  large  vas 
aberrans.  The  level  at  which  a  high  division  takes  place  is  most  frequently 
in  the  upper  third  of  the  arm,  less  so  in  the  lower  third,  and  it  is  of  rarest 
occurrence  in  the  middle  third.  When  two  arteries  are  present  they  usually 
lie  side  by  side  in  the  position  of  the  normal  vessel.  When  a  vas  aberrans 
is  present  it  usually  arises  from  the  upper  part  of  the  brachial  artery,  and 
terminates  below  by  joining,  most  commonly,  the  radial  artery. 


THE   UPPER  LIMB  319 

2.  In  rare  cases  the  brachial  artery  divides  high  up  into  two  vessels  of  equal 
size,  which  become  reunited  into  one  trunk  a  little  above  the  elbow. 

3.  When  a  supracondylar  process  is  present  the  brachial  artery,  along  with 
the  median  nerve,  may  descend  towards  the  internal  epicondyle  until  it 
gets  below  the  level  of  the  process,  round  which  it  turns  forward  to  the 
front  of  the  elbow.  This  is  the  normal  course  taken  by  the  artery  in  the 
Felidce,  in  which  there  is  a  supracondylar  foramen. 

Collateral  Circulation. — When  the  brachial  artery  has  been 
ligatured  above  the  centre  of  the  arm,  the  collateral  circulation  is 
carried  on  by  the  superior  profunda  artery,  which  anastomoses 
below  with  (i)  the  radial  recurrent,  (2)  the  posterior  interosseous 
recurrent,  and  (3)  the  anastomotica  magna.  When  the  artery  has 
been  ligatured  in  the  vicinity  of  the  elbow,  the  inferior  profunda 
and  anastomotica  magna  assist  the  superior  profunda  by  anasto- 
mosing with  the  anterior  and  posterior  ulnar  recurrent. 

Brachial  Venae  Comites. — These  are  two  in  number,  and  they 
closely  accompany  the  artery,  one  being  placed  on  either  side  of 
it.  Along  the  course  of  the  vessel  they  communicate  with  each 
other  across  it  at  frequent  intervals.  Superiorly  the  external  vena 
comes  crosses  inwards  over  the  lower  portion  of  the  third  part  of 
the  axillary  artery  to  join  the  internal  vena  comes,  and  the  resulting 
trunk  opens  into  the  axillary  vein  near  the  lower  border  of  the 
subscapularis. 

The  internal  cutaneous  nerve  and  the  nerve  of  Wrisberg  are 
situated  on  the  inner  side  of  the  brachial  artery,  the  former  slightly 
encroaching  upon  it.  The  median  nerve  lies  on  the  outer  side  of  the 
artery  as  low  as  the  centre  of  the  arm,  where  it  passes  over  it, 
and  then  descends  on  its  inner  side  in  the  lower  third.  Instead 
of  crossing  over  the  vessel  it  may  pass  behind  it.  It  gives  off  no 
branch  in  the  arm,  but  it  sometimes  receives  a  branch  from  the 
musculo-cutaneous.  The  ulnar  nerve  lies  on  the  inner  side  of  the 
artery  as  low  as  the  insertion  of  the  coraco-brachialis.  Here  it 
meets  with  the  inferior  profunda  artery,  and  with  it  pierces  the 
internal  intermuscular  septum  from  before  backwards.  It  then 
descends  on  the  inner  head  of  the  triceps  to  the  interval  between  the 
olecranon  and  internal  epicondyle.  It  gives  off  no  branch  in  the 
arm.  The  musculo-cutaneous  nerve,  having  pierced  the  coraco- 
brachialis,  passes  downwards  and  outwards  between  the  biceps 
and  brachialis  anticus.  A  little  above  the  elbow  it  appears  at  the 
outer  border  of  the  biceps,  whence  it  descends  to  its  cutaneous 
distribution,  already  described.  Before  piercing  the  coraco- 
brachialis,  it  gives  off  the  branch  to  that  muscle,  and,  as  it  courses 
between  the  biceps  and  brachialis  anticus,  it  furnishes  branches  to 
them.  It  sometimes  gives  a  communicating  branch  to  the  median 
nerve. 

Anticubital  Space. — This  is  the  name  given  to  the  triangular 
hollow  in  front  of  the  elbow-joint.  The  roof  of  the  space  is  formed 
by  the  integument,  median  basilic  and  median  cephalic  veins, 
anterior  division  of  the  internal  cutaneous  nerve,  cutaneous  part 
of  the  musculo-cutaneous  nerve,  deep  fascia,  and  semilunar  fascia. 


320 


A  MANUAL  OF  ANATOMY 


The  floor  is  formed  by  the  brachiaHs  anticus  and  a  small  part  of  the 
supinator  radii  brevis.  The  base  is  represented  by  an  imaginary 
line  connecting  the  epicondyles  of  the  humerus.  The  outer  boundary 
is  formed  by  the  brachio-radialis,  and  the  inner  by  the  pronator  radii 
teres,  the  apex  being  constructed  by  the  former  muscle  overlapping 


Internal  Cutaneous  Nerve 
Basilic  Vein._. 

Median  Nerve 

Brachial  Artery  and 

Venas  Comites 
Posterior  Branch  of 

Posterior  Ulnar  Vein    _?lll 

Anterior  Branch  of 
Internal  Cutaneous  Nerve 
Median  Basilic  Vein 

J 
Bicipital  Fascia- - 


Ulnar  Artery  and 

Venae  Comites 


Anterior  Ulnar  Vein  — 


Pronator  Radii  Teres 


Median  Cephalic  Vein 


Radial  Vein 


Deep  Median  Vein 

Radial  Recurrent 

Artery 

Radial  Artery  and 

Vense  Comites 


Median  Vein 
Brachio-radialis 


Fig.   184. — Superficial  Dissection  of  the  Front  of  the  Left  Elbow. 


the  latter.  The  space  contains  the  terminal  part  of  the  brachial, 
and  the  commencement  of  the  radial  and  ulnar,  arteries,  with  their 
respective  venae  comites.  On  the  outer  side  of  the  brachial  artery 
is  the  tendon  of  the  biceps,  and  on  its  inner  side  is  the  median 
nerve.  Under  cover  of  the  brachio-radialis  are  the  radial  and 
posterior  interosseous  branches  of  the  musculo-spiral  nerve. 


THE   UPPER  LIMB  321 

BACK  OF  THE  BRACHIAL  REGION. 

Triceps  Extensor  Cubiti — Origin. — {t.)  The  long  head  arises  from 
the  infraglenoid  ridge  of  the  scapula,  where  it  is  superficially  ten- 
dinous. (2)  The  external  head  arises  from  {a)  the  outer  part  of  the 
posterior  surface  of  the  humerus,  reaching  as  high  as  the  insertion 
of  the  teres  minor,  and  as  low  as  the  spiral  groove ;  and  {b)  the 
back  of  the  external  intermuscular  septum  above  the  point  where 
it  is  pierced  by  the  musculo-spiral  nerve.  (3)  The  Internal  head 
arises  from  [a)  the  whole  of  the  posterior  surface  of  the  humerus 
below  the  spiral  groove,  reaching  upwards  on  the  inner  side  of  the 
groove,  in  a  tapering  manner,  as  high  as  a  point  about  \  inch  above, 
and  posterior  to,  the  lower  border  of  the  insertion  of  the  teres 
major  ;  (&)  the  back  of  the  internal  intermuscular  septum  over 
its  whole  extent ;  and  (c)  the  back  of  the  external  inter- 
muscular septum  below  where  it  is  pierced  by  the  musculo-spiral 
nerve. 

Insertion. — (i)  The  back  part  of  the  upper  surface  of  the  olecranon 
process  of  the  ulna  ;  (2)  the  deep  fascia  covering  the  anconeus  ;  and 
(3)  slightly  into  the  posterior  ligament  of  the  elbow-joint. 

The  long  and  external  heads  terminate  in  a  broad  flat  tendon, 
which  occupies  about  the  lower  half  of  the  arm,  the  fibres  of  the 
long  head  ending  on  its  inner  side,  and  those  of  the  external  head 
on  its  upper  and  outer  parts.  Most  of  the  fibres  of  the  internal 
head  terminate  on  the  deep  surface  of  the  tendon,  but  some  are 
inserted  directly  into  the  olecranon.  The  deepest  and  lowest  fibres 
of  this  head  are  inserted  into  the  posterior  ligament  of  the  elbow- 
joint,  and  form  the  so-called  subanconeus.  There  is  usually  a 
bursa  over  the  front  part  of  the  upper  surface  of  the  olecranon, 
separating  the  tendon  of  the  muscle  from  the  posterior  ligament 
of  the  elbow- joint. 

The  long  head  is  related  to  the  lower  part  of  the  capsular  ligament 
of  the  shoulder- joint. 

Nerve-supply. — The  musculo-spiral  nerve,  which  is  a  branch  of 
the  posterior  cord  of  the  brachial  plexus,  its  fibres  being  derived 
from  the  last  four  cervical,  and  sometimes  from  the  first  thoracic. 

Action. — The  external  and  internal  heads  ai-e  simple  extensors 
of  the  elbow- joint.  The  long  head  also  extends  the  elbow-joint, 
and  from  its  relation  to  the  shoulder-joint  it  depresses  the  arm 
uj)on  the  scapula. 

Musculo-spiral  Nerve. — This  nerve  at  first  lies  behind  the  third 
part  of  the  axillary  artery,  and  then  behind  the  upper  part  of  the 
brachial.  Thereafter  it  passes  downwards  and  backwards,  with  the 
superior  profunda  artery,  between  the  long  and  internal  heads  of 
the  triceps.  It  next  winds  round  the  back  of  the  humerus  in  the 
spiral  groove,  between  the  external  and  internal  heads  of  the  triceps. 
Having  pierced  the  upper  part  of  the  external  intermuscular 
septum,  it  descends  in  the  groove  between  the  brachio-radialis 
and  brachialis  anticus  to  a  point  a  little  above  the  external  epi- 

21 


322 


A   MANUAL  OF  ANATOMY 


condyle,  where  it  terminates  by  dividing  into  the  radial  and  posterior 
interosseous  nerves. 

Branches — Internal  Branches. — ^These,  which  arise  on  the  inner 


Latissimus  Dorsi 

Teres  Major 4iS 

Long  Head  of  Triceps.  _  -^gj^ 
Internal  Head  of  Triceps 


Ulnar  Nerve  behind  Internal 

Epicondyle 


Teres  Minor 


_  External  Head  ot 
Triceps 


Musculo-spiral  Nerve 

and  Superior 

Profunda  Artery 


Tendon  of  Triceps 

External  Epicondyle 

Anconeus 


Fig.  185. — Dissection  of  the  Back  of  the  Brachial  Region. 

(The  External  Head  of  the  Triceps  has  been  divided  and  reflected  outwards 

to  show  the  contents  of  the  Spiral  Groove.) 

side  of  the  humerus,  are  muscular  and  cutaneous.  The  muscular 
branches  supply  the  long  and  internal  heads  of  the  triceps, 
those  for  the  long  head  entering  it  high  up,  whilst  those  for  the 
internal  head  enter  it  at  different  levels.     One  of  the  latter,  which 


THE   UPPER  LIMB  323 

is  remarkable  for  its  length,  descends,  along  with  the  ulnar  nerve, 
to  enter  the  internal  head  low  down,  this  branch  being  known  as 
the  ulnar  collateral  nerve  (Krause).  The  internal  cutaneous  branch 
usually  arises  in  common  with  one  of  the  muscular  branches,  and 
is  distributed  to  the  integument  of  the  back  of  the  arm,  reaching 
nearly  as  low  as  the  back  of  the  elbow. 

Posterior  Branches. — These  arise  behind  the  humerus,  and  are 
distributed  to  the  external  and  internal  heads  of  the  muscle  and 
to  the  anconeus,  the  nei've  to  the  latter,  which  is  long  and  slender, 
descending  in  the  internal  head. 

External  Branches. — These  arise  on  the  outer  side  of  the 
humerus,  and  are  cutaneous,  muscular,  and  articular.  The  upper 
and  lower  external  cutaneous  nerves  have  been  already  described. 
The  muscular  branches  are  distributed  to  the  brachio-radialis, 
extensor  carpi  radialis  longior,  and  brachialis  anticus,  the  latter 
branch  being  a  small  twig.  The  articular  branches,  one  or  two  in 
number,  are  distributed  to  the  elbow-joint. 


THE  SHOULDER- JOINT. 

The  shoulder-joint  belongs  to  the  class  diarthrosis,  and  to  the 
subdivision  enarthrosis  (ball-and-socket).  The  articular  surfaces 
are  the  glenoid  cavity  of  the  scapula  and  the  head  of  the  humerus ; 
and  the  ligaments  are  the  capsular,  coraco-humeral,  gleno-humeral, 
and  glenoid. 

The  capsular  ligament  is  attached  to  the  scapula  around  the 
margin  of  the  glenoid  cavity  close  to  the  glenoid  ligament,  with 
which  many  of  its  fibres  are  connected.  Superiorly  it  extends  to 
the  root  of  the  coracoid  process,  and  inferiorly  it  is  connected  with 
the  long  head  of  the  triceps.  At  the  humerus  it  is  attached  to  the 
anatomical  neck,  its  fibres  descending  for  a  little  on  the  inferior 
aspect.  The  ligament  is  very  loose,  so  that,  when  the  muscles  in 
contact  with  it  have  been  divided,  the  head  of  the  humerus  drops 
away  from  the  glenoid  cavity  for  over  an  inch.  The  ligament 
presents  two  openings.  One,  called  the  foramen  ovale,  is  situated 
on  its  anterior  aspect,  behind  the  upper  border  of  the  subscapular  is. 
Through  this  opening  a  protrusion  of  the  synovial  membrane  of 
the  joint  takes  place  beneath  the  upper  border  of  the  subscapu- 
laris,  where  it  forms  the  subscapular  bursa.  The  other  opening  is 
placed  between  the  great  and  small  tuberosities  of  the  humerus  at 
the  commencement  of  the  bicipital  groove,  and  it  allows  the  long 
tendon  of  the  biceps,  with  its  synovial  investment,  to  leave  the 
interior  of  the  joint,  beneath  the  transverse  humeral  ligament. 
There  is  sometimes  a  third  opening  of  small  size  on  the  posterior 
aspect  of  the  capsule,  which  allows  the  synovial  membrane  to 
jjrotrude  and  form  a  bursa  beneath  the  infraspinatus. 

The  coraco-humeral  ligament  is  a  strong  band  which  extends 

21 — 2 


324 


A  MANUAL  OF  ANATOMY 


from  the  outer  border  of  the  coracoid  process,  near  the  root,  across 
the  upper  part  of  the  capsule,  with  which  it  is  closely  connected, 
to  the  great  tuberosity  of  the  humerus. 

The  gleno-humeral  bands  are  three  in  number,  and  are  thickened 
parts  of  the  capsule  which  project  in  an  inward  direction.  The 
superior  band  is  known  as  the  gleno-humeral  ligament,  and  is 
regarded  as  representing  the  ligamentum  teres  of  the  hip-joint.  It 
extends  from  the  apex  of  the  glenoid  cavity,  and  the  root  of  the 
coracoid  process,  of  the  scapula  to  the  small  tuberosity  of  the 
humerus,  where  it  lies  on  the  inner  side  of  the  bicipital  groove. 
The  middle  band,  called  Flood's  ligament,  extends  from  the  anterior 


Coraco-acroniial  Ligament 


Foramen  Ovale 

-^-  Subscapularis  (reflected) 
', Capsular  Ligament 


.Long  Head  of  Biceps 


Fig.   i! 


-The  Right  Shoulder-Joint  (Anterior  View). 


margin  of  the  glenoid  cavity  to  the  lower  part  of  the  small  tuber- 
osity of  the  humerus.  The  inferior  band,  called  Sehlemm's  liga- 
ment, extends  from  the  lower  part  of  the  glenoid  cavity  to  the 
lower  part  of  the  neck  of  the  humerus.  The  gleno-humeral  bands 
are  best  seen  when  the  joint  is  opened  from  behind.  Associated 
with  the  capsule  there  is  also  the  transverse  humeral  ligament, 
which  bridges  over  the  upper  end  of  the  bicipital  groove  between 
the  great  and  small  tuberosities. 

The  glenoid  ligament  is  a  dense  fibro-cartilaginous  band  which 
is  implanted  on  the  edge  of  the  glenoid  cavity,  and  so  deepens  it 
for  the  head  of  the  humerus.  Externally  it  is  connected  with  the 
capsular  ligament,  and  superiorly  each  lateral  division  blends  with 
the  long  head  of  the  biceps. 

The  long  head  of  the  biceps  is  to  be  regarded  in  the  light  of  a 


THE  UPPER  LIMB 


325 


ligament,  inasmuch  as  it  arches  over  the  head  of  the  humerus,  and 
tends  to  prevent  upward  displacement  of  the  bone. 

The  synovial  membrane  lines  the  inner  surface  of  the  glenoid 
ligament,  and  is  reflected  from  it  over  the  inner  surface  of  the 
capsule.  From  this  it  passes  to  the  anatomical  neck  of  the  humerus, 
which  it  covers  as  far  as  the  margin  of  the  articular  cartilage 
of  the  head.  It  protrudes  through  the  opening  in  the  front  of  the 
capsule  to  form  the  subscapular  bursa,  and  it  sometimes  protrudes 
through  an  opening  behind  to  form  a  bursa  beneath  the  infra- 
spinatus. The  long  head  of  the  biceps,  in  passing  from  the  supra- 
glenoid  tubercle  to  the  bicipital  groove,  receives  a  tubular  invest- 
ment from  it.     This  accompanies  the  tendon  for  a  short  distance  m 


Capsule  of  Acromio-clavicular  Joint         Coraco-acromial  Ligamenl 


Long  Head  of  Biceps-' 


Capsular  Ligament . 
(cut) 


Trapezoid  Ligament 
Conoid  Ligament 


Glenoid  Ligament 


Fig.  187.— The  Right  Glenoid  Cavitv,  and  the  Adjacent  Ligaments. 

the  bicipital  groove,  after  which  it  is  reflected  upwards  to  become 
continuous  with  the  synovial  membrane  lining  the  capsule. 

Muscular  Relations.— The  capsular  ligament  is  closely  related 
to  the  following  muscles :  superiorly,  the  supraspinatus ;  fos- 
teriorly,  from  above  downwards,  infraspinatus  and  teres  minor  ; 
inferiorly,  long  head  of  the  triceps  ;  and  anteriorly,  subscapulans. 

Arterial  Supply.— The  suprascapular,  and  anterior  and  posterior 
circumflex,  arteries. 

Nerve-supply.— The  suprascapular  and  circumflex  nerves. 

Movements.— Seven  movements  are  allowed  at  the  shoulder-joint,  namely 
forward  flexion,  as  in  shaking  hands,  extension,  backward  flexion,  abduction, 
adduction,  rotation,  and  circumduction.  ,1 

Muscles  concerned  in  the  Movements  -Forward  Flexion.— The  clavicular 
parts  of  the  ijectoralis  major  aiul  deltoid,  sliorl  lu'ad  ot  the  biceps,  and  coraco- 
brachialis.      Extension.— The  spinal  p(jrtion  of  the  deltoid,  teres  major,  and 


326 


A   MANUAL  OF  ANATOMY 


latissiraus  dorsi.  Backward  Flexion. — This  movement  being  a  continua- 
tion backwards  of  extension,  the  muscles  concerned  are  the  same  as  for  that 
movement.  Abduction. — The  acromial  portion  of  the  deltoid  and  supra- 
spinatus.  Adduction. — The  sterno-costal  portion  of  the  pectoralis  major, 
short  head  of  the  biceps,  coraco-brachialis,  teres  major,  and  latissimus  dorsi. 


Suprascapular  Nerve 
Transverse  Lig 
Post.  Belly  of 
Omo-hyoid 


Suprascapular  Artery 


Capsular  Ligament 


Infra- 
spinatus 


Spino-glenoid 
Ligament 


Teres  Minor 


Long  Head  of  Triceps 

Fig.   i88. — The  Right  Shoulder-Joint  (Posterior  View). 

External   Rotation. — Infraspinatus  and    teres    minor.     Internal    Rotation. — 

Subscapularis,  pectoralis  major,  teres  major,  and  latissimus  dorsi.  Circum- 
duction.— This  movement,  being  a  combination  of  iiexion,  abduction,  exten- 
sion, and  adduction,  is  effected  by  the  various  muscles  concerned  in  these 
movements. 


THE  FOREARM  AND  HAND. 

Cutaneous  Nerves. — Along  the  front  of  the  outer  side  of  the  fore- 
arm is  the  anterior  branch  of  the  cutaneous  part  of  the  musculo- 
cutaneous, and  along  the  back  are  its  posterior  branch  and  the  lower 
external  cutaneous  branch  of  the  musculo-spiral.  Along  the  front 
and  back  of  the  inner  side  are  the  anterior  and  posterior  divisions 
of  the  internal  cutaneous.  All  these  nerves  have  been  already  de- 
scribed. A  small  cutaneous  branch  of  the  ulnar  nerve  is  given  off 
from  it  about  the  centre  of  the  forearm,  which,  after  piercing  the 
deep  fascia  and  communicating  with  the  anterior  branch  of  the 
internal  cutaneous,  has  a  limited  distribution  to  the  integument 
just  below  the  centre,  internal  to  the  median  line.  This  branch 
is  not  constant. 

The  integument  of  the  palm  of  the  hand  is  supplied  by  the 
palmar  cutaneous  branches  of  the  ulnar,  median,  and  radial.     The 


THE   UPPER  LIMB 


337 


palmar  cutaneous  branch  of  the  ulnar  arises  in  common  with  the 
branch  to  the  integument  of  the  forearm  and  descends  on  the  ulnar 
artery,  keeping  beneath  the  deep  fascia  until  it  approaches  the 
wrist,  where  it  becomes  cutaneous  on  the  outer  side  of  the  tendon  of 
the  flexor  carpi  ulnaris.  It  then  passes  over  the  anterior  annular 
ligament,  and  is  distributed  to  the  integument  of  the  inner  part  of 
the  palm.  The  palmar  cutaneous  branch  of  the  median  arises  a 
little  above  the  wrist,  and  pierces  the  deep  fascia  just  above  the 
anterior  annular  ligament,  in  the  interval  between  the  tendons  of 
the  flexor  carpi  radialis  and  palmaris  longus.     It  then  descends 


Dorsal  Branch  of  Ul; 


Median 


Fig.  li 


-Diagram  of  the  Nerves  of  the  Hand 
(Dorsal  Aspect). 


over  the  anterior  annular  ligament,  and  is  distributed  to  the  in- 
tegument of  the  outer  part  of  the  palm,  and  slightly  to  that  of  the 
thenar  eminence.  It  communicates  internally  with  the  palmar 
cutaneous  of  the  ulnar,  and  externally  with  that  of  the  radial.  The 
palmar  cutaneous  branch  of  the  radial  arises  from  the  external 
division  of  the  nerve  which  })asses  to  the  outer  side  of  the  thumb. 
It  is  joined  by  a  twig  from  the  anterior  branch  of  the  musculo- 
cutaneous, and  is  distributed  to  the  integument  of  the  thenar 
eminence. 

The  integument  of  the  dorsum  of  the  hand  and  fingers  is  supplied 


328  A  MANUAL  OF  ANATOMY 

by  the  radial  nerve  and  the  dorsal  branch  of  the  ulnar.  The 
radial  nerve  winds  backwards  beneath  the  tendon  of  the  brachio- 
radialis  about  3  inches  above  the  wrist,  and  then  divides  into  two 
branches — external  and  internal.  The  external  branch  passes  to 
supply  the  outer  side  of  the  thumb,  giving  off  in  its  course  the 
palmar  cutaneous  branch.  The  internal  branch,  having  com- 
municated with  the  posterior  branch  of  the  musculo-cutaneous,  and 
having  given  a  branch  to  the  back  of  the  wrist  which  communicates 
with  the  dorsal  branch  of  the  ulnar,  divides  into  four  digital  nerves. 
The  first  supplies  the  inner  side  of  the  thumb,  the  second  the  outer 
side  of  the  index  finger,  the  third  bifurcates  at  the  cleft  between  the 
index  and  middle  fingers  into  two  collateral  branches  for  the  supply 
of  their  contiguous  sides,  and  the  fourth  passes  to  the  cleft  between 
the  middle  and  ring  fingers.  The  latter  in  its  course  is  reinforced 
by  an  offset  from  the  dorsal  branch  of  the  ulnar,  and  then  it  divides 
into  two  collateral  nerves  for  the  supply  of  the  contiguous  sides  of 
the  middle  and  ring  fingers. 

The  dorsal  branch  of  the  ulnar  nerve  arises  about  2^  inches 
above  the  wrist,  and  winds  backwards  beneath  the  tendon  of  the 
flexor  carpi  ulnaris.  It  then  gives  a  branch  to  the  back  of  the 
wrist,  which  communicates  with  a  branch  of  the  radial,  and  there- 
after is  distributed  as  follows  :  one  branch  supplies  the  inner 
side  of  the  little  finger  ;  a  second  branch  passes  to  the  cleft 
between  the  little  and  ring  fingers,  giving  an  offset  to  the  innermost 
digital  branch  of  the  radial,  and  it  divides  into  two  collateral 
branches  for  the  supply  of  the  contiguous  sides  of  these  fingers  ; 
whilst  a  third  branch  is  distributed  to  the  integument  of  the  back 
of  the  hand. 

The  distribution  of  the  dorsal  digital  nerves  is  as  follows  :  on  the 
thumb  they  extend  as  far  as  the  nail,  on  the  index  finger  to  the 
distal  end  of  the  second  phalanx,  on  the  middle  finger  to  near  the 
distal  end  of  the  first  phalanx,  on  the  ring-finger  to  near  the  distal 
end  of  the  second  phalanx,  and  on  the  little  finger  as  far  as  the 
nail.  The  portions  of  integument  not  supplied  by  the  dorsal 
digital  nerves  derive  their  innervation  from  branches  which  pass 
backwards  from  the  palmar  digital  branches  of  the  median  and 
ulnar  nerves. 

Veins. — ^The  superficial  veins  of  the  forearm,  already  described, 
are  the  radial,  median,  anterior  ulnar,  and  posterior  ulnar.  On  the 
back  of  the  hand  is  the  dorsal  venous  plexus,  and  in  front  of  the 
anterior  annular  ligament  is  the  anterior  plexus,  of  small  size.  The 
dorsal  venous  plexus  receives  the  superficial  digital  veins,  which  com- 
mence in  plexuses  in  the  region  of  the  nails.  They  are  two  in  number 
to  each  finger,  one  being  placed  on  each  side  towards  the  dorsal 
aspect.  These  veins  form  cross  arches  above  and  below  the  inter- 
phalangeal  joints  on  the  backs  of  the  fingers.  At  the  clefts  the 
collateral  veins  unite  to  form  in  each  case  a  single  trunk,  and  these 
trunks  end  in  the  dorsal  venous  plexus.  The  superficial  digital 
vein  from  the  inner  side  of  the  little  finger  passes  to  the  commence- 


THE  UPPER  LIMB  329 

ment  of  the  posterior  ulnar  vein,  and  is  known  as  the  vena  salvatella 
or  '  saving  vein.'  The  blood  is  conveyed  away  from  the  outer  side 
of  the  dorsal  venous  plexus  by  the  radial  vein,  and  from  the  inner 
side  by  the  posterior  ulnar  vein.  The  radial  vein  receives  a  com- 
municating branch  from  the  venae  comites  of  the  deep  palmar  arch 
at  the  proximal  end  of  the  first  interosseous  space.  The  posterior 
ulnar  vein  receives  a  communicating  branch  from  the  venae  comites 
of  the  profunda  branch  of  the  ulnar  artery,  which  passes  beneath  the 
abductor  minimi  digiti  muscle. 

The  anterior  venous  plexus  receives  its  radicles  from  the  palm, 
and  the  blood  is  conveyed  away  from  it  by  the  median  vein.  The 
anterior  ulnar  vein,  as  stated,  commences  on  the  inner  aspect  of  the 
front  of  the  wrist. 

Deep  Fascia  of  the  Forearm. — The  deep  fascia  is  of  considerable 
strength,  its  fibres  being  principally  transverse,  though  some  are 
disposed  longitudinally  and  obliquely.  Superiorly,  below  the 
internal  epicondyle,  it  receives  the  semilunar  fascia  of  the  biceps, 
and  behind  it  gets  an  accession  of  fibres  from  the  tendon  of  the 
triceps.  In  front  of  the  elbow  it  presents  an  opening  for  the  passage 
of  the  deep  median  vein.  In  the  region  of  the  epicondyles  it  serves 
as  a  common  tendon  of  origin  to  the  muscles  arising  from  these 
prominences,  and  it  sends  between  them  strong  intermuscular  septa 
which  afford  additional  origin  to  them,  and  are  readily  recognised  on 
the  surface  by  white  lines.  It  is  attached  above  to  the  epicondyles 
of  the  humerus  and  the  margins  of  the  triangular  surface  on  the  back 
of  the  olecranon  process  of  the  ulna,  and  along  the  forearm  to  the 
posterior  border  of  the  latter  bone.  Anteriorly  it  sends  an  ex- 
pansion between  the  superficial  and  deep  muscles,  and  it  acts  in  a 
similar  manner  on  the  posterior  aspect,  where  the  fascia  is  stronger 
than  in  front.  At  the  wrist  it  blends  with  the  anterior  annular  liga- 
ment, and  posteriorly  it  forms  the  posterior  annular  ligament. 


FRONT  OF  THE  FOREARM. 

Muscles.— The  muscles  of  the  front  of  the  forearm  are  arranged 
in  three  layers — first  or  superficial,  second  or  intermediate,  and 
third  or  deep. 

First  Layer. — The  muscles  comprising  this  layer  are,  in  order  from 
without  inwards,  the  pronator  radii  teres,  flexor  carpi  radiali?, 
palmaris  longus  (inconstant),  and  flexor  carpi  ulnaris. 

I.  Pronator  Radii  Teres. — This  muscle  arises  by  two  heads — 
superficial  or  humeral,  and  deep  or  coronoid.  The  superficial  head, 
which  is  of  large  size,  arises  from  (i)  the  front  and  upper  part  of  the 
internal  epicondyle,  and  lower  part  of  the  internal  supracondylar 
ridge,  of  the  humerus;  (2)  the  common  tendon;  and  (3)  the  inter- 
muscular septa  between  it  and  the  flexor  carpi  radialis  externally, 
and  flexor  sublimis  digitorum  deeply.  The  deep  head,  which  is  of 
small  size,  arises  from  the  inner  margin  of  the  coronoid  process  of  the 


330  A   MANUAL  OF  ANATOMY 

ulna,  and,  after  a  short  course,  it  joins  the  deep  surface  of  the  super- 
ficial head  at  an  acute  angle. 

Insertion. — By  means  of  a  fiat  tendon,  about  i^  inches  broad, 
into  the  rough  impression  on  the  outer  surface  of  the  radius  at  its 
centre,  where  the  curve  of  the  bone  is  most  prominent. 

Nerve-supply. — ^The  median  nerve,  which  arises  from  the  outer  and 
inner  cords  of  the  brachial  plexus,  its  fibres  being  derived  from  the 
last  four  cervical  and  first  thoracic  nerves.  The  branches  are  given 
off  just  before  the  median  nerve  passes  between  the  two  heads  of 
origin  of  the  muscle. 

The  muscle  is  directed  downwards  and  outwards. 

Action. — (i)  To  pronate  the  forearm,  and  (2)  to  assist  inflexion 
of  the  elbow-joint. 

The  median  nerve  passes  between  the  two  heads  of  the  muscle,  and 
the  ulnar  vessels  beneath  its  deep  head. 

The  muscle  may  have  a  third  head,  arising  from  the  internal  inter- 
muscular septum  of  the  arm,  or  from  a  supracondylar  process,  and, 
when  this  is  so,  it  bridges  over  the  brachial  artery  and  median 
nerve. 

2.  Flexor  Carpi  Radialis — Origin. — (i)  The  front  of  the  internal 
epicondyle  by  means  of  the  common  tendon  ;  (2)  the  deep  fascia 
covering  the  muscle  ;  and  (3)  the  intermuscular  septa  separating  it 
from  the  pronator  radii  teres  externally,  palmaris  longus  internally, 
and  flexor  sublimis  digitorum  deeply. 

Insertion. — ^The  front  of  the  base  of  the  second  metacarpal  bone, 
and  by  a  small  slip  into  the  front  of  the  base  of  the  third. 

The  muscle  presents  a  fusiform,  fleshy  belly  in  the  upper  half  of  the 
forearm,  which  is  replaced  in  the  lower  half  by  a  strong,  flat  tendon. 

Nerve-supply. — ^The  median  nerve. 

The  direction  of  the  muscle  is  downwards  and  outwards. 

Action. — (i)  To  flex  the  wrist-joint,  and  (2)  to  assist  in  flexion  of 
the  elbow-joint. 

The  tendon  of  the  muscle  passes  through  a  special  compart- 
ment of  the  anterior  annular  ligament,  where  it  traverses  the 
groove  on  the  palmar  surface  of  the  trapezium,  and  the  radial 
vessels  lie  upon  the  outer  side  of  the  tendon  in  the  lower  half  of  the 
forearm. 

3.  Palmaris  Longus — Origin. — (i)  The  front  of  the  internal  epi- 
condyle by  means  of  the  common  tendon  ;  (2)  the  deep  fascia  cover- 
ing the  muscle  ;  and  (3)  the  intermuscular  septa  separating  it  from 
the  flexor  carpi  radialis  externally,  flexor  carpi  ulnaris  internally, 
and  flexor  sublimis  digitorum  deeply. 

Insertion. — (i)  The  upper  part  of  the  central  division  of  the  palmar 
fascia,  and  (2)  the  front  of  the  anterior  annular  ligament  at  its 
lower  part. 

Nerve-supply. — ^The  median  nerve. 

Action. — (i)  To  render  tense  the  central  division  of  the  palmar 
fascia  ;  (2)  to  assist  in  flexing  the  wrist-joint ;  and  (3)  to  assist 
feebly  in  flexing  the  elbow- joint. 


THE   UPPER  LIMB 


331 


The  palmaris  longus  is  the  representative  of  an  original  super- 
ficial flexor  of  the  fingers,  the  expanded  portion  of  the  tendon  of 
which  remains  as  the  palmar  fascia. 

4.  Flexor  Carpi  Ulnaris. — ^This  muscle  arises  by  two  heads.     One 


Biceps   -V  — 


Brachialis  Amicus 


Brachio-radialis-- 


Flexor  Subliniis  Digitorum 
Flexor  Longus  Pollicis 

Pronator  Quadratus 
Anterior  Annular  Ligament 


Pronator  Radii  Teres 


Flexor  Carpi  Radialis 


.  _  Palmaris  Longus 


Flexor  Carpi  Ulnaris 


Palmaris  Brevis 


Fig.   190. — The  Superficial  Muscles  ok  the  Fkont  of 
THE  Forearm. 

head  arises  from  (i)  the  front  of  the  internal  epicondyle  by  means 
of  the  common  tendon  ;  (2)  the  deep  fascia ;  and  (3)  the  inter- 
muscular septa  between  it  and  the  palmaris  longus  and  flexor  sub- 
limis  digitorum.  The  other  head  arises  from  (i)  the  inner  aspect 
of  the  olecranon  process,  and  (2)  the  upper  two-thirds  of  the  posterior 


332  A   MANUAL  OF  ANATOMY 

border,  of  the  ulna,  by  an  aponeurosis  common  to  it,  tiie  flexor 
profundus  digitorum,  and  extensor  carpi  ulnaris. 

Insertion. — ^The  pisiform  bone.  From  the  tendon  of  insertion 
two  prolongations  are  given  off,  known  as  the  pisi-uncinate  and  pisi- 
metacarpal  ligaments,  the  former  being  attached  to  the  anterior 
border  of  the  hook  of  the  unciform  bone,  and  the  latter  to  the  front 
of  the  base  of  the  fifth  metacarpal.  The  tendon  also  gives  off 
laterally  a  band  to  the  anterior  annular  ligament. 

Nerve-supfly. — The  ulnar  nerve,  which  is  a  branch  of  the  inner 
cord  of  the  brachial  plexus,  its  fibres  being  derived  from  the  eighth 
cervical  and  first  thoracic. 

The  fibres  are  directed  downwards  and  forwards,  and  terminate 
on  the  posterior  aspect  of  the  tendon  which  appears  about  the 
centre  of  the  forearm. 

Action. — (i)  To  flex  and  adduct  the  wrist-joint,  and  (2)  to  flex 
feebly  the  elbow-joint. 

The  ulnar  nerve  and  posterior  ulnar  recurrent  artery  pass  between 
the  two  heads  of  the  muscle. 

Second  Layer. — Flexor  Sublimis  Digitorum  (flexor  perforatus) — 
Origin. — The  upper  part  arises  from  (i)  the  internal  epicondyle  ; 
(2)  the  intermuscular  septum  between  it  and  the  first  layer  ;  (3)  the 
internal  lateral  ligament  of  the  el  bow- joint ;  and  (4)  the  tubercle 
on  the  inner  margin  of  the  coronoid  process  of  the  ulna.  The 
lower  part,  broad  and  thin,  arises  from  the  anterior  oblique  line  of 
the  radius. 

Insertion. — By  four  tendons  into  the  sides  of  the  second 
phalanges  of  the  four  inner  fingers,  at  their  centre  and  on  their 
anterior  aspect. 

The  muscle  in  the  lower  part  of  the  forearm  is  replaced  by  four 
tendons  which  pass  beneath  the  anterior  annular  ligament  in  pairs. 
The  tendons  of  the  anterior  pair  are  for  the  middle  and  ring 
fingers,  whilst  those  of  the  posterior  pair  are  for  the  index  and  little 
fingers.  In  this  situation,  as  well  as  for  a  little  above  the  wrist,  and 
as  low  as  about  the  centre  of  the  palm,  they  are  invested,  along  with 
the  deep  flexor  tendons,  by  the  great  palmar  bursa,  to  be  afterwards 
described.  In  the  palm  the  four  tendons  diverge,  and  each  is  accom- 
panied by  a  tendon  of  the  flexor  profundus  digitorum,  which  lies 
beneath  it.  At  the  commencements  of  the  digits  each  pair  of  tendons 
enters  the  sheath  on  the  palmar  aspect  of  a  finger,  which  binds  them 
to  the  first  and  second  phalanges.  Towards  the  distal  end  of  the  first 
phalanx  the  flexor  sublimis  tendon  splits  into  two  parts  to  allow  the 
flexor  profundus  tendon  to  pass  through.  The  two  divisions  of  the 
superficial  tendon  are  folded  round  the  deep  tendon,  and  unite 
beneath  it  at  the  proximal  end  of  the  second  phalanx.  Beyond  this 
point  the  superficial  tendon  is  grooved  to  support  the  deep  tendon, 
and  then  divides  into  its  two  parts  of  insertion.  The  sheath  and  its 
accessories  will  be  afterwards  described. 

Nerve-supply. — ^The  median  nerve. 

Action. — (i)  To  flex  the  second  phalanges  of  the  four  inner  fingers  ; 


THE    UPPER  LIMB 


333 


Brachial  Artery  Median  Nerve 


Biceps 


Brachio-radialis Ll  J 


Radial  Nerve 
Radial  Recurrent  Artery- 
Radial  Artery 


Superficial  Head  of  Pronator 
Radii  Teres  (cut) 


Flexor  Longus  Pollicis 

Radial  Artery. 
Brachio-radialis, 

Flexor  Carpi  Radialis 

Pronator  Quadratus 

Extensor  Ossis  Metacarjji 
Pollicis 


Abductor  Pollicis. 
Superficial  Head  of  Flexor.. 
Brevis  Pollicis 


Brachialis  Anticus 


Superficial   Head  of  Pro- 
nator Radii  Teres  (cut) 


, i_i^^I_  __  Flexor  Carpi  Radialis 

"■^» Ulnar  Artery 

.Palmaris  Longus 


■~  Deep  Head  of  Pronator 
Radii  Teres 


I Flexor  Carpi  Ulnaris 


Flexor  Sublimis 

Digitorum 


jVIedian  Nerve 

Palmaris  Longus 
Ulnar  Artery 
Ulnar  Nerve 

Flexor  Carpi  Ulnaris 


, Palmaris  Brevis 


Palmar  Fascia 


Fig.   191. — The  Front  of  the  Fokearm,  and  Palm  ok  the  Hand. 


334  A   MANUAL  OF  ANATOMY 

{2)  to  flex  their  metacarpo-phalangeal  joints  ;  (3)  to  flex  the  wrist- 
joint  ;  and  (4)  to  assist  in  flexion  of  the  elbow-joint. 

Radial  Artery. — The  radial  artery  is  one  of  the  terminal  branches 
of  the  brachial,  from  which  it  arises  in  the  anticubital  space,  opposite 
the  upper  part  of  the  neck  of  the  radius.  It  is  smaller  than  the  ulnar, 
which  is  the  other  terminal  branch,  and  in  point  of  direction  the 
vessel  is  the  continuation  of  the  brachial.  Its  destination  is  the 
palm,  to  reach  which  it  passes  at  first  downwards  and  slightly 
outwards,  as  low  as  the  styloid  process  of  the  radius.  Here  the 
vessel  passes  to  the  back  of  the  wrist  beneath  the  styloid  process 
and  upon  the  external  lateral  ligament,  after  which  it  sinks  between 
the  two  heads  of  the  abductor  indicis  muscle.  In  this  way  it 
reaches  the  palm,  where  it  anastomoses  with  the  profunda  branch 
of  the  ulnar  artery,  and  so  forms  the  deep  palmar  arch.  The  vessel 
is  divided  into  three  parts.  The  first  part  lies  in  front  of  the  fore- 
arm, the  second  on  the  back  of  the  wrist,  and  the  third  in  the  palm. 

First  Part. — This  part  extends  from  the  origin  to  the  styloid  pro- 
cess of  the  radius.  Its  direction  is  downwards  and  slightly  outwards, 
and  its  course  may  be  indicated  by  a  line  drawn  from  a  point  just 
below  the  bend  of  the  elbow,  midway  between  the  epicondyles 
of  the  humerus,  to  a  point  about  h  inch  internal  to  the  styloid  process 
of  the  radius.  In  the  upper  third  the  vessel  lies  between  the 
brachio-radialis  externally  and  pronator  radii  teres  internally, 
being  overlapped  by  the  fleshy  belly  of  the  former.  Thereafter  it 
is  placed  between  the  brachio-radialis  externally  and  flexor  carpi 
radialis  internally,  and  in  the  lower  half  of  the  forearm,  where 
these  muscles  are  replaced  by  their  tendons,  the  vessel  is  quite 
superficial. 

Relations — Stiperficial. — The  integument,  and  margin  of  the 
brachio-radialis  in  the  upper  third,  or  more.  Branches  of  the 
musculo-cutaneous  nerve  are  distributed  over  the  line  of  the  vessel. 
Deep. — From  above  downwards  it  lies  upon  (i)  the  tendon  of  inser- 
tion of  the  biceps  ;  (2)  the  supinator  radii  brevis  ;  (3)  the  tendon  of 
insertion  of  the  pronator  radii  teres  ;  (4)  the  radial  origin  of  the  flexor 
sublimis  digitorum  ;  (5)  the  flexor  longus  poUicis  ;  (6)  the  pronator 
quadratus  ;  and  (7)  the  lower  end  of  the  radius.  External. — ^The 
brachio-radialis  throughout  the  whole  of  the  forearm,  and  the 
external  vena  comes.  The  radial  nerve  in  the  upper  part  lies  a  little 
to  the  outer  side  of  the  vessel ;  at  the  centre  it  is  closer  to  it ;  and  in 
the  lower  part  the  nerve  leaves  the  artery  by  turning  backwards 
beneath  the  tendon  of  the  brachio-radialis.  Internal. — The  in- 
ternal vena  comes,  pronator  radii  teres  in  the  upper  third,  and 
thereafter  the  flexor  carpi  radialis. 

Branches  of  the  First  Part. — The  first  part  gives  ofl  the  following 
branches,  namely,  radial  recurrent,  muscular,  anterior  radial 
carpal,  and  superficial  volar. 

The  radial  recurrent  artery,  usually  of  large  size,  arises  from  the 
outer  side  of  the  radial  close  to  its  commencement,  and  passes  out- 
wards beneath  the  brachio-radialis,  where  it  rests  on  the  supinator 


THE   UPPER  LIMB  335 

radii  brcvis.  Here  it  divides  into  branches  which  come  into 
relation  with  the  musculo-spiral  nerve  and  its  terminal  divisions. 
Most  of  these  are  distributed  to  the  muscles  arising  from  the  ex- 
ternal epicondyle,  and  they  anastomose  with  the  posterior  inter- 
osseous recurrent.  One  branch,  however,  ascends  with  the  musculo- 
spiral  nerve  between  the  brachio-radialis  and  brachialis  anticus, 
and  anastomoses  with  the  anterior  terminal  branch  of  the  superior 
profunda  of  the  brachial.  The  radial  recurrent  also  gives  articular 
twigs  to  the  elbow-joint. 

The  muscular  branches  arise  at  frequent  intervals  along  the  forearm. 

The  anterior  radial  carpal  artery,  of  small  size,  arises  from  the 
inner  side  of  the  radial  at  the  level  of  the  lower  border  of  the  pro- 
nator quadratus,  along  which  it  passes  inwards,  lying  deeply  beneath 
the  flexor  tendons.  At  the  middle  line  it  anastomoses  with  the  an- 
terior ulnar  carpal  artery  to  form  the  anterior  carpal  arch.  This 
arch  is  reinforced  from  above  by  the  anterior  branch  of  the  anterior 
interosseous  artery,  and  from  below  by  the  recurrent  branches  of  the 
deep  palmar  arch.  In  this  manner  the  anterior  carpal  arch  is  con- 
verted into  a  rete,  the  branches  of  which  are  distributed  to  the  wrist- 
joint,  and  the  carpal  articulations  and  bones. 

The  superficial  volar  artery  arises  either  below  the  preceding,  or 
sometimes  above  it.  It  passes  downwards  over,  or  through,  the 
thenar  muscles,  in  which,  if  of  small  size,  it  terminates.  When 
large,  it  reaches  the  palm,  and  anastomoses  with  the  ulnar  artery 
to  complete  the  superficial  palmar  arch. 

Varieties  of  the  First  Part. — (i)  The  artery  may  arise  high  up  from  the 
brachial,  or  axillary.  (2)  When  of  high  origin,  it  may  descend  superlicial  to 
the  semilunar  fascia  of  the  biceps  and  deep  fascia  of  the  forearm.  (3)  The 
artery  may  turn  backwards  over  the  brachio-radialis  just  below  the  centre 
of  the  forearm.  (4)  It  may  be  joined  by  a  vas  aberrans  from  the  brachial, 
or  axillary.  (5)  It  may  terminate  at  the  lower  part  of  the  forearm,  its  dis- 
tribution being  taken  up  by  the  ulnar,  median,  or  anterior  interosseous. 

The  second  and  third  parts  of  the  radial  artery  will  be  afterwards 
described. 

Radial  Venae  Comites. — The  radial  artery  is  accompanied  by  two 
vena  comites,  which  are  placed  one  on  either  side  of  the  vessel,  and 
they  communicate  at  frequent  intervals  by  transverse  branches 
lying  upon  it.  They  terminate  above  by  uniting  to  form  the 
external  brachial  vena  comes. 

Radial  Nerve. — The  radial  nerve  is  one  of  the  terminal  branches 
of  the  musculo-spiral,  its  fibres  being  derived  from  the  sixth  cervical, 
and  sometimes  from  the  fifth  and  seventh.  It  passes  straight  down- 
wards under  cover  of  the  brachio-radialis,  lying  at  first  a  little  to 
the  outer  side  of  the  radial  artery,  then  getting  closer  to  it  at  the 
centre  of  the  forearm,  and  finally  leaving  the  vessel  in  the  lower 
part  by  turning  backwards  beneath  the  tendon  of  the  brachio- 
radialis  on  its  way  to  its  cutaneous  distribution,  which  has  been 
already  described.  It  is  a  sensory  nerve,  and  gives  off  no  branches 
until  it  reaches  the  back  of  the  limb. 


336  A   MANUAL  OF  ANATOMY 

Posterior  Interosseous  Nerve. — ^This  is  the  other  and  larger 
terminal  branch  of  the  musculo-spiral,  its  fibres  being  derived  from 
the  sixth,  seventh,  and  sometimes  the  eighth,  cervical.  After  a 
short  downward  course  under  cover  of  the  brachio-radialis,  it 
winds  round  the  outer  side  of  the  radius,  passing  through  the 
supinator  radii  brevis.  Having  reached  the  back  of  the  limb  near 
the  lower  border  of  that  muscle,  it  descends,  in  company  with  the 
posterior  interosseous  artery,  between  the  superficial  and  deep  groups 
of  muscles.  At  the  upper  border  of  the  extensor  longus  pollicis  it 
leaves  the  artery  and  passes  beneath  that  muscle,  where  it  meets 
the  posterior  branch  of  the  anterior  interosseous  artery  on  the  back 
of  the  interosseous  membrane.  Thereafter  it  passes  through  the 
groove  on  the  back  of  the  radius  for  the  extensor  communis  digi- 
torum  and  extensor  indicis,  lying  beneath  the  tendons  and  the 
posterior  annular  ligament.  It  terminates  on  the  back  of  the  wrist 
in  a  gangliform  enlargement,  from  which  branches  are  given  off 
to  the  wrist- joint  and  carpal  articulations. 

Branches. — The  branches  are  muscular  and  articular. 

Muscular  Branches. — Before  piercing  the  supinator  radii  brevis 
the  nerve  gives  branches  to  that  muscle  and  to  the  extensor  carpi 
radialis  brevior.  After  reaching  the  back  of  the  forearm,  it  supplies 
the  extensor  communis  digitorum,  extensor  minimi  digiti,  extensor 
carpi  ulnaris,  the  three  extensors  of  the  thumb,  and  the  extensor 
indicis. 

Ariiciilar  Branches. — ^These  arise  from  the  terminal  gangliform 
enlargement,  and  are  distributed  to  the  wrist- joint  and  carpal 
articulations. 

Ulnar  Artery. — The  ulnar  artery  is  the  larger  of  the  two  terminal 
branches  of  the  brachial,  and  it  arises  in  the  anticubital  space 
opposite  the  upper  part  of  the  neck  of  the  radius.  Its  destination 
is  the  palm,  which  it  reaches  by  passing  over  the  anterior  annular 
ligament,  and  there  it  forms  the  superficial  palmar  arch.  It  is 
at  first  directed  downwards  and  inwards  beneath  both  heads  of 
the  pronator  radii  teres,  flexor  carpi  radialis,  palmaris  longus, 
and  flexor  sublimis  digitorum,  and  it  here  describes  a  slight  curve, 
the  convexity  of  which  is  directed  inwards.  Having  gained  the 
front  of  the  ulna  it  meets  the  ulnar  nerve  a  little  above  the  centre 
of  the  forearm,  and  it  then  descends  on  the  outer  side  of  the  nerve, 
both  structures  resting  on  the  flexor  profundus  digitorum,  and 
being  overlapped  by  the  flexor  carpi  ulnaris.  A  little  above  the 
wrist  the  artery  lies  superficially  on  the  outer  side  of  the  tendon 
of  that  muscle.  It  then  crosses  over  the  anterior  annular  ligament, 
lying  close  to  the  outer  side  of  the  pisiform  bone,  with  the  inter- 
vention of  the  ulnar  nerve,  and  shortly  thereafter  it  turns  outwards 
in  the  palm  towards  the  thenar  muscles.  The  vessel  is  divided 
into  three  parts — first,  second,  and  third. 

First  Part. — ^This  part  extends  from  the  origin  to  the  upper 
border  of  the  anterior  annular  ligament.  On  account  of  the  curve 
of  the  vessel  at  first  no  definite  line  can  be  given  to  indicate  its 


THE  UPPER  LIMB 


337 


Biceps 

Musculo-spiral  Nerve. - 
Brachio-radialis-   ' 

Radial  Nerve- 
Radial  Recurrent  Arterj'.. 
Posterior  Interosseous  Nerve-- 
Ulnar  Artery-- 
Supinator  Radii  Brevis-- 
Radial  Artery  -- 

Pronator  Radii  Teres  _. 


Flexor  Longus  Pollicis 
Anterior  Interosseous  Nerve 


Brachio-radiali 


Superficial  Volar  Artery 
Extensor  Ossis  Metacarpi 
Pollicis 


Opponens  Pollicis  - 

Superficial  Head  of  Flexor 
Brevis  Pollicis 


Brachialis  Anticus 
Ai  -  -V_  Median  Nerve 
L  Brachial  Artery 


Pronator  Radii  Teres 

Flexor  Carpi  Radialis 
Palmaris  Longus 

Flexor  Carpi  Ulnaris 
Ulnar  Nerve 

Ulnar  Artery 


Flexor  Profundus  Digitorum 
Anterior  Interosseous  Artery 


-Pronator  Quadratus 


Median  Nerve 


-Abductor  Pollicis 


Superficial  Palmar  Arch 


Fig.   192. — Deep  Dissection  of  Front  of  Right  Forearm, 
AND   Superficial  Dissection  of  Palm. 


22 


338  A  MANUAL  OF  ANATOMY 

entire  course,  but  in  the  lower  half  of  the  forearm  the  border  of  the 
flexor  carpi  ulnaris  is  the  guide. 

Relations — Superficial. — In  the  upper  half  of  the  forearm  the 
artery  is  deeply  placed,  being  covered  by  both  heads  of  the  pronator 
radii  teres,  flexor  carpi  radialis,  palmaris  longus,  and  flexor  sub- 
limis  digitorum.  In  the  lower  half  it  is  overlapped  by  the  tendon 
of  the  flexor  carpi  ulnaris,  except  for  a  little  above  the  wrist,  where 
it  lies  superficially  on  the  outer  side  of  that  tendon.  The  palmar 
cutaneous  branch  of  the  ulnar  nerve  descends  over  the  artery  in 
the  lower  half.  Deep. — Brachialis  anticus  for  about  i  inch,  and 
thereafter  the  flexor  profundus  digitorum.  External. — ^The  external 
vena  comes,  and,  in  the  lower  half,  the  flexor  sublimis  digitorum. 
Internal. — ^The  internal  vena  comes,  ulnar  nerve  for  rather  more  than 
the  lower  half,  and  the  tendon  of  the  flexor  carpi  ulnaris  for  a  little 
above  the  wrist.  The  nerves  related  to  the  first  part  of  the  artery 
are  the  median,  ulnar,  and  palmar  cutaneous  branch  of  the  ulnar. 
The  median  nerve  lies  for  a  little  at  first  on  the  inner  side  of  the 
vessel,  but,  at  the  point  where  the  vessel  passes  beneath  the  deep 
head  of  the  pronator  radii  teres,  the  nerve  crosses  it,  being  separated 
from  it  by  the  deep  head  of  that  muscle,  and  so  gains  its  outer  side. 
The  ulnar  nerve,  having  come  from  behind  the  internal  epicondyle, 
is  widely  separated  from  the  artery  for  rather  more  than  the  upper 
third  of  the  forearm.  A  little  above  the  centre  the  nerve  and  artery 
meet,  and  then  descend  in  close  contact,  the  nerve  being  on  the 
inner  side,  with  the  intervention  of  the  internal  vena  comes.  The 
palmar  cutaneous  branch  of  the  ulnar  nerve,  as  stated,  descends 
over  the  lower  half  of  the  vessel. 

Branches  of  the  First  Part. — The  first  part  gives  off  the  following 
branches,  namely,  anterior  ulnar  recurrent,  posterior  ulnar  re- 
current, common  interosseous  (giving  off  anterior  and  posterior 
interosseous),  muscular,  posterior  ulnar  carpal,  and  anterior  ulnar 
carpal. 

The  anterior  ulnar  recurrent  artery,  of  small  size,  passes 
upwards  and  inwards  on  the  brachialis  anticus  and  beneath  the 
superficial  head  of  the  pronator  radii  teres,  to  supply  these  muscles 
and  anastomose  with  the  anterior  branch  of  the  anastomotica 
magna  of  the  brachial. 

The  posterior  ulnar  recurrent  artery,  of  large  size,  arises  just 
below  the  preceding,  or  sometimes  in  common  with  it.  It  passes 
inwards  beneath  the  flexor  sublimis  digitorum,  and  then  ascends 
with  the  ulnar  nerve  between  the  two  heads  of  the  flexor  carpi 
ulnaris  to  the  interval  between  the  internal  epicondyle  and  olecranon 
process.  It  supplies  the  adjacent  muscles,  ulnar  nerve,  and  elbow- 
joint,  and  it  anastomoses  with  the  inferior  profunda  and  posterior 
branch  of  the  anastomotica  magna.  It  also  gives  twigs  over  the 
back  of  the  olecranon,  which  anastomose  with  the  posterior  inter- 
osseous recurrent,  thus  forming  the  olecranon  rete. 

The  common  interosseous  artery  is  a  short,  thick  trunk,  which 
arises,  below  the  preceding,  about  i  inch  from  the  commencement 


THE  UPPER  LIMB  339 

of  the  ulnar.  It  is  directed  backwards  to  the  upper  border  of  the 
interosseous  membrane,  where  it  divides  into  the  anterior  and 
posterior  interosseous  arteries. 

(i)  The  anterior  interosseous  artery  descends  on  the  front  of  the 
interosseous  membrane,  having  a  vena  comes  on  either  side  of  it, 
and  the  anterior  interosseous  nerve  on  its  outer  side.  It  lies 
between  the  flexor  longus  pollicis  externally  and  the  flexor  profundus 
digitorum  internally,  both  of  which  overlap  it,  and  at  the  upper 
border  of  the  pronator  quadratus  it  divides  into  two  terminal 
branches,  anterior  and  posterior. 

Branches. — ^These  are  as  follows :  the  median  artery  (comes 
nervi  mediani)  is  a  long,  slender  branch  which  arises  from  the 
commencement  of  the  vessel.  It  at  once  gets  in  contact  with  the 
median  nerve,  which  it  accompanies  beneath  the  flexor  sublimis 
digitorum,  supplying  the  nerve  and  that  muscle.  If  of  large  size, 
it  passes  beneath,  or  over,  the  anterior  annular  ligament  into  the 
palm,  where  it  may  join  the  superficial  palmar  arch,  or  if  that 
should  be  abnormal,  it  furnishes  certain  digital  arteries.  Muscular 
branches  are  given  off  to  the  deep  layer  of  muscles,  and  to  the 
extensor  muscles  of  the  thumb  on  the  back  of  the  interosseous 
membrane.  The  branches  to  the  latter  muscles  pierce  the  mem- 
brane. The  nutrient  or  medullary  arteries  enter  the  radius  and 
ulna.  The  anterior  terminal  branch  descends  beneath  the  pro- 
nator quadratus  and  joins  the  anterior  carpal  arch.  The  posterior 
terminal  branch,  which,  passing  backwards  through  the  interosseous 
membrane,  and  having  anastomosed  with  the  posterior  interosseous, 
descends  beneath  the  extensor  tendons  and  the  posterior  annular 
ligament  to  the  back  of  the  wrist,  where  it  joins  the  posterior 
carpal  arch. 

(2)  The  posterior  interosseous  artery  passes  backwards  between 
the  upper  border  of  the  interosseous  membrane  and  the  oblique 
ligament.  At  the  back  of  the  forearm  it  appears  between  the 
supinator  radii  brevis  and  extensor  ossis  metacarpi  pollicis,  where 
it  is  joined  by  the  posterior  interosseous  nerve.  The  artery,  with 
the  nerve,  then  descends  between  the  superficial  and  deep  group 
of  muscles  until  it  reaches  the  upper  border  of  the  extensor  longus 
pollicis.  Here  the  artery  leaves  the  nerve,  and  passes  over  that 
muscle  and  the  extensor  indicis.  At  the  lower  border  of  the 
latter  muscle  it  anastomoses  with  the  posterior  terminal  branch 
of  the  anterior  interosseous,  and  then  ends  in  articular  branches 
to  the  wrist- joint,  though  it  may  pass  to  join  the  posterior  carpal 
arch. 

Branches. — ^These  are  as  follows  :  the  posterior  interosseous  re- 
current arises  as  soon  as  the  vessel  reaches  the  back  of  the  forearm. 
It  passes  upwards  beneath  the  anconeus  to  the  back  of  the  external 
epicondyle,  where  it  anastomoses  with  the  posterior  branch  of  the 
superior  profunda  of  the  brachial.  It  also  gives  twigs  over  the 
back  of  the  olecranon  process  which  anastomose  with  branches 
of  the  posterior  ulnar  recurrent,  and  so  form  the  olecranon  rete. 

22 — 2 


340 


A  MANUAL  OF  ANATOMY 


In  addition,  it  anastomoses  with  the  muscular  branches  of  the 
radial  recurrent.  Muscular  branches  supply  the  adjacent  muscles. 
Articular  branches  are  given  off  to  the  wrist-joint. 

The  muscular  branches  of  the  first  part  of  the  ulnar  artery  arise 
at  frequent  intervals  along  the  forearm. 

The  posterior  ulnar  carpal  artery  arises  a  little  above  the  pisiform 
bone,  and  passes  backwards  beneath  the  tendon  of  the  flexor  carpi 
ulnaris  to  the  back  of  the  wrist.     Here  it  turns  outwards  beneath 


Brachial  Artery. 

Brachialis  Anticus 

Anastomotica  Magna 

Artery 


Tendon  of  Biceps 

Brachio-radialis  — 

Radial  Recurrent  Artery 
Supinator  Radii  Brevis 

Ext.  Carpi  Radialis 

Longior 
Radial  Artery- 


Common  Interosseous.. 
Artery 


—  Triceps 


Int.  Intermuscular 
Septum 


Posterior  Branch  of 
Anastomotica  Magna 


Anterior  Branch  of 
Anastomotica  Magna 


Pron.  Radii  Teres 


Common  Origin  of 
Superf.  Flexors 
Anterior  Ulnar 
Recurrent  Artery 
.Posterior  Ulnar 
Recurrent  Artery 


Flexor  Profundus 

Digitorum 
Ulnar  Artery 


Fig.   193. — Deep  Dissection  of  the  Front  of  the  Right  Elbow 
(after  Tiedemann). 


the  extensor  tendons,  and  anastomoses  with  the  posterior  radial 
carpal  and  posterior  branch  of  the  anterior  interosseous  to  form 
the  posterior  carpal  arch.  It  may  give  off  the  dorsal  digital  artery 
of  the  inner  side  of  the  little  finger. 

The  anterior  ulnar  carpal  artery  arises  opposite  the  lower  border  of 
the  pronator  quadratus.  It  passes  outwards  along  the  lower  border 
of  that  muscle  beneath  the  flexor  profundus  digitorum,  and  anas- 
tomoses with  the  anterior  radial  carpal,  the  anterior  branch  of 
the  anterior  interosseous,  and  the  recurrent  branches  of  the  deep 
palmar  arch,  to  form  the  anterior  carpal  arch  or  rete. 

Anastomoses    round    the    Elbow-Joint. — ^The     anastomoses    of 


THE   UPPER  LIMB 


341 


arteries  round  the  elbow- joint  are  very  free.  In  front  of  the 
internal  epicondyle  of  the  humerus  the  anterior  branch  of  the 
anastomotica  magna  of  the  brachial  anastomoses  with  the  anterior 
ulnar  recurrent.  Behind  the  internal  epicondyle  the  inferior 
profunda  and  the  posterior  branch  of  the  anastomotica  magna 
(both  of  the  brachial)  anastomose  with  the  posterior  ulnar 
recurrent.  In  front  of  the  external  epicondyle  the  anterior  ter- 
minal branch  of  the  superior  profunda  of  the  brachial  anastomoses 
with  the  radial  recurrent.     Behind  the  external   epicondyle   the 


Inferior  Profund 


Posterior  Branch  of 
.Anastomotica  Magna 

Internal  Epicondyle.. 
Olecranon  Rete 


Posterior  Ulnar  Recurrent 


Superior  Profunda 
(Posterior  Branch) 


Arterial  Arch 
-External  Epicondyle 


"-_---•- Branches  of  Radial 
Recurrent 


Posterior  Interosseous 

Recurrent 


Posterior  Interosseous 


Fig.   194. — The  Anastomoses  round  the  Right  Elbow-Joint 
(Posterior  View)  (after  Tiedemann). 


posterior  terminal  branch  of  the  superior  profunda  anastomoses 
with  the  posterior  interosseous  recurrent.  Upon  the  back  of  the 
shaft  of  the  humerus,  immediately  above  the  olecranon  fossa,  a 
transverse  anastomosis  takes  place  between  the  posterior  branches 
of  the  superior  profunda  and  anastomotica  magna,  both  of  the 
brachial.  Upon  the  back  of  the  olecranon  process  is  the  olecranon 
arterial  rete,  which  is  formed  by  branches  of  the  posterior  inter- 
osseous recurrent  and  posterior  ulnar  recurrent. 

Varieties. — (i)  The  ulnar  artery  may  arise  high  up   from  tiie  brachial,  or 
axillary.     In  cases  of  high  origin  the  vessel  usually  descends  over  the  muscles 


342  A  MANUAL  OF  ANATOMY 

arising  from  the  internal  epicondyle  of  the'  humerus,  and  beneath  the  deep 
fascia,  though  it  may  be  superficial  to  it.  In  such  cases  the  common  inter- 
osseous is  a  branch  of  the  main  trunk,  and  it  furnishes  the  anterior  and 
posterior  ulnar  recurrent  arteries.  (2)  The  artery,  though  normal  in  origin, 
may  pass  superficial  to  the  muscles  arising  from  the  internal  epicondyle. 

Second  Part  of  the  Ulnar  Artery. — The  second  part  lies  upon  the 
anterior  annular  ligament,  and  extends  from  its  upper  to  its  lower 
border.  It  has  a  vena  comes  on  either  side  of  it,  and  the  ulnar 
nerve  on  its  inner  side.  It  lies  on  the  outer  side  of  the  pisiform 
bone,  by  which  it  is  overhung,  and  on  the  inner  side  of  the  hook 
of  the  unciform  bone,  where  it  is  under  cover  of  the  pisi- uncinate 
ligament. 

Relations — Superficial. — The  integument,  the  expansion  from  the 
flexor  carpi  ulnaris  tendon  to  the  front  of  the  anterior  annular 
ligament,  and  the  pisi-uncinate  ligament.  Deep. — The  anterior 
annular  ligament.  External. — ^The  external  vena  comes,  and  hook 
of  the  unciform  bone.  Internal. — ^The  internal  vena  comes,  ulnar 
nerve,  and  pisiform  bone. 

The  branches  of  this  part  are  unimportant. 

The  third  part  of  the  ulnar  artery  will  be  described  in  connection 
with  the  palm. 

Ulnar  Venae  Comites. — The  ulnar  artery  in  the  first  and  second 
parts  of  its  course  is  accompanied  by  two  venae  comites,  one  being 
placed  on  either  side  of  the  vessel,  and  the  two  communicate  at 
frequent  intervals  by  transverse  branches  which  lie  upon  it.  They 
commence  in  the  venae  comites  of  the  inner  parts  of  the  superficial 
and  deep  palmar  arches,  and  they  terminate  above  by  uniting  to 
form  the  internal  brachial  vena  comes. 

Ulnar  Nerve. — ^The  ulnar  nerve  enters  the  forearm  by  passing 
through  the  interval  between  the  internal  epicondyle  and  olecranon 
process,  where  it  lies  between  the  two  heads  of  the  flexor  carpi 
ulnaris.  It  then  descends  under  cover  of  that  muscle,  lying  upon 
the  flexor  profundus  digitorum.  A  little  above  the  centre  of  the 
forearm  it  meets  with  the  ulnar  artery,  upon  the  inner  side  of 
which  it  subsequently  lies.  On  approaching  the  wrist  it  escapes 
from  beneath  the  flexor  carpi  ulnaris,  and  lies,  with  the  artery,  close 
to  the  outer  side  of  its  tendon.  It  then  passes  over  the  anterior 
annular  ligament  close  to  the  outer  side  of  the  pisiform  bone, 
by  which  it  is  overhung,  and  subsequently  on  the  inner  side  of 
the  hook  of  the  unciform  bone.  Thereafter  it  enters  the  palm, 
where  it  divides  into  its  two  terminal  branches,  superficial  and 
deep. 

Branches. — ^These  are  articular,  muscular,  and  cutaneous. 

The  articular  branches,  two  or  three  in  number,  are  given  off  to 
the  elbow-j  oint  as  the  nerve  passes  between  the  internal  epicondyle 
and  olecranon  process. 

The  muscular  branches  arise  in  the  upper  part  of  the  forearm, 
and  are  distributed  to  the  flexor  carpi  ulnaris  and  the  inner  portion 
of  the  flexor  profundis  digitorum. 


THE  UPPER  LIMB  343 

The  cutaneous  branches  are  three  in  number,  and  have  been 
already  described. 

The  ulnar  nerve  in  the  palm  will  be  afterwards  described. 

Median  Nerve. — The  median  nerve  lies  at  first  in  the  anticubital 
space,  where  it  is  placed  on  the  inner  side  of  the  brachial  and  ulnar 
arteries.  On  leaving  the  space  it  passes  between  the  two  heads  of 
the  pronator  radii  teres,  where  it  crosses  the  ulnar  artery,  the  deep 
head  of  that  muscle  intervening  between  the  two.  It  then  passes 
beneath  the  radial  origin  of  the  flexor  sublimis  digitorum,  and 
descends  under  cover  of  that  muscle  in  the  middle  line,  until  it 
approaches  the  wrist.  Here  it  escapes  from  beneath  the  muscle, 
and  lies  between  its  tendons  and  that  of  the  flexor  carpi  radialis, 
where  it  parts  with  its  palmar  cutaneous  branch.  Thereafter  it 
passes  under  the  anterior  annular  ligament  into  the  palm,  where 
it  will  be  afterwards  described.  The  nerve  is  accompanied  by  the 
median  artery,  which  is  a  branch  of  the  anterior  interosseous  near 
its  origin. 

Branches. — The  branches  of  the  nerve  in  the  forearm  are  articular, 
muscular,  and  cutaneous. 

The  articular  branches,  one  or  two  in  number,  enter  the  elbow- 
joint  on  its  anterior  aspect. 

The  muscular  branches  supply  all  the  muscles  on  the  front  of 
the  forearm,  except  the.  flexor  carpi  ulnaris  and  the  inner  portion 
of  the  flexor  profundus  digitorum.  The  branch,  or  branches, 
to  the  pronator  radii  teres  arise  from  the  nerve  before  it  passes 
between  the  two  heads  of  that  muscle.  The  branches  for  the 
flexor  carpi  radialis,  palmaris  longus,  and  flexor  sublimis  digitorum 
arise  lower  down.  The  flexor  longus  pollicis,  outer  portion  of  the 
flexor  profundus  digitorum,  and  pronator  quadratus  are  supplied 
by  the  anterior  interosseous  branch.  This  long  branch  arises  from 
the  median  just  below  the  neck  of  the  radius,  and  it  descends  on 
the  front  of  the  interosseous  membrane,  lying  on  the  outer  side  of 
the  anterior  interosseous  artery,  both  being  overlapped  by  the 
contiguous  borders  of  the  flexor  profundus  digitorum  and  flexor 
longus  pollicis.  On  reaching  the  upper  border  of  the  pronator 
quadratus  the  nerve  passes  beneath  that  muscle,  and  ends  in  two 
branches,  one  of  which  enters  the  deep  surface  of  the  muscle,  whilst 
the  other  passes  to  supj^ly  the  wrist- joint.  The  branch  to  the 
outer  portion  of  the  flexor  profundus  digitorum  arises  high  up, 
and  it  communicates  in  the  muscle  with  the  branch  of  the  ulnar 
nerve  to  its  inner  portion.  The  anterior  interosseous  nerve  in  its 
course  furnishes  an  interosseous  branch,  which  is  distributed  to  the 
interosseous  membrane,  and  gives  off  medullary  filaments  which 
accompany  the  medullary  arteries  of  the  radius  and  ulna. 

Third  Layer  of  Muscles. — The  muscles  comprising  the  third  or 
deep  layer  are  three  in  number,  namely,  the  flexor  profundus 
digitorum,  flexor  longus  polliris,  and  pronator  (piadratus. 

I.  Flexor  Profundus  Digitorum  (flexor  perforans)  —  Origin. — 
(i)  The  ujjper  three-fourths  of   the  anterior  surface  of   the  ulna; 


344  -4   MANUAL  GF  ANATOMY 

(2)  the  inner  half  of  the  front  of  the  interosseous  membrane ;  (3)  the 
upper  two-thirds  of  the  inner  surface  of  the  ulna  ;  and  (4)  the 
posterior  border  of  the  bone  for  a  similar  extent,  by  an  aponeurosis 
common  to  it,  the  flexor  carpi  ulnaris,  and  extensor  carpi  ulnaris. 

Insertion. — ^The  front  of  the  bases  of  the  distal  phalanges  of 
the  four  inner  fingers. 

The  tendinous  part  of  the  muscle  makes  its  appearance  about 
the  centre  of  the  forearm,  and  the  index-finger  tendon  is  usually 
separate  from  the  rest  of  the  tendinous  mass  over  the  greater  part 
of  its  extent.  The  other  three  tendons  become  separate  beneath 
the  anterior  annular  ligament,  so  that  in  the  palm  there  are  four 
diverging  tendons,  connected  with  which  are  the  lumbricales.  Each 
deep  flexor  tendon  accompanies  a  superficial  flexor  tendon,  beneath 
which  it  lies,  and  both  enter  the  sheath  on  the  palmar  aspect  of  a 
finger.  Opposite  the  distal  end  of  the  first  phalanx  the  deep  tendon 
passes  through  the  cleft  in  the  superficial  tendon,  and  so  reaches  its 
more  distant  point  of  insertion. 

Nerve-supply. — (i)  The  anterior  interosseous  branch  of  the 
median  supplies  that  portion  of  the  muscle  which  acts  upon 
the  index  finger,  and  in  part  the  portion  acting  upon  the  middle 
and  ring  fingers  ;  and  (2)  the  ulnar  nerve  supplies  that  portion 
which  acts  upon  the  little  finger,  and  in  part  the  portion  acting 
upon  the  ring  and  middle  fingers.  Sometimes  the  anterior 
interosseous  nerve  supplies  the  whole  01  the  portion  acting  upon 
the  middle  finger. 

Action. — (i)  To  flex  the  distal  phalanges  of  the  four  inner  fingers  ; 
(2)  to  assist  in  flexing  the  second  phalanx  and  metacarpo-phalangeal 
joint  ;  and  (3)  to  assist  in  flexing  the  wrist-joint. 

2.  Flexor  Longus  Pollicis — Origin. — (i)  The  anterior  surface  of 
the  radius,  from  the  anterior  oblique  line  above  to  the  upper  border 
of  the  pronator  quadratus  below  ;  (2)  the  outer  half  of  the  front 
of  the  interosseous  membrane  ;  and  (3)  as  a  rule  by  a  tendinous 
slip  from  the  inner  margin  of  the  coronoid  process  of  the  ulna,  or 
from  the  internal  epicondyle  of  the  humerus. 

Insertion. — The  front  of  the  base  of  the  distal  phalanx  of  the  thumb. 

The  tendon  appears  on  the  front  of  the  muscle  about  the  centre 
of  the  forearm,  and  receives  fleshy  fibres  untfl  it  is  near  the  wrist. 

Nerve-supply. — ^The  anterior  interosseous  nerve. 

Action.- — (ij  To  flex  the  distal  phalanx  of  the  thumb  ;  (2)  to 
assist  in  flexing  its  metacarpo-phalangeal  joint ;  and  (3)  to  act  as 
an  auxiliary  flexor  of  the  wrist- joint. 

3.  Pronator  Quadratus — Origin. — The  front  of  the  ulna  over  its 
lower  fourth. 

Insertion. — The  front  of  the  radius  for  about  2  inches  at  its 
lower  end,  and  the  anterior  part  of  the  inner  surface. 

Nerve-supply. — The  anterior  interosseous  nerve. 

The  fibres  are  disposed,  for  the  most  part,  transversely,  and  the 
muscle  is  covered  by  a  firm  aponeurosis  over  about  its  inner  third. 

Action. — -To  pronate  the  radius  upon  the  ulna. 


THE   UPPER  LIMB  345 


FRONT  OF  THE  WRIST  AND  PALM. 

Landmarks. — Below,  and  internal  to,  the  styloid  process  of  the 
radius  the  tuberosity  of  the  scaphoid  can  be  felt,  and  below  this  the 
tuberosity  of  the  trapezium.  On  the  inner  aspect  of  the  front  of  the 
wrist  the  pisiform  bone  can  easily  be  felt,  and  below,  and  external  to, 
it,  the  hook  of  the  unciform  bone.  The  interval  between  these  two 
projections  indicates  the  position  of  the  ulnar  vessels  and  nerve. 
The  centre  of  the  palm  presents  a  triangular  hollow,  the  apex  of 
which  is  directed  upwards  and  inwards  towards  the  wrist,  and  the 
base  downwards  towards  the  roots  of  the  fingers,  in  which  latter 
situation  there  is  a  transverse  prominence,  broken  up  by  grooves 
leading  to  the  four  inner  digits.  The  palmar  hollow  is  bounded 
above  and  externally  by  the  thenar  eminence,  and  internally  by 
the  hypothenar  eminence. 

The  integument  of  the  palm  presents  four  furrows,  two  being 
disposed  transversely,  and  two  more  or  less  longitudinally.  The 
lower  transverse  furrow  is  about  i  inch  above  the  roots  of  the  inner 
three  digits,  and  is  most  conspicuous  when  the  fingers  are  flexed. 
It  commences  at  the  inner  border  of  the  palm,  and,  passing  outwards 
in  a  slightly  arched  manner,  it  terminates  at  the  cleft  between  the 
index  and  middle  fingers.  It  is  produced  by  the  flexion  of  the 
metacarpo-phalangeal  joints  of  the  inner  three  fingers.  These 
joints  are  situated  about  midway  between  this  line  and  the  roots  of 
the  fingers  when  these  are  extended.  The  upper  transverse  furrow 
commences  at  the  outer  border  of  the  palm  about  f  inch  above 
the  root  of  the  index  finger,  and  it  passes  inwards  and  slightly 
upwards  to  the  inner  border  of  the  palm,  lying  about  ^  inch  above 
the  lower  furrow.  The  outer  part  of  this  furrow  is  due  to  flexion 
of  the  metacarpo-phalangeal  joint  of  the  index  finger,  and  the 
remainder  to  complete  flexion  of  the  metacarpo-phalangeal  joints  of 
the  inner  three  fingers.  One  of  the  longitudinal  furrows  commences 
about  the  centre  of  the  wrist,  and  curves  downwards  and  outwards 
to  meet  the  upper  transverse  furrow.  It  is  produced  by  flexion  of 
the  joint  between  the  trapezium  and  metacarpal  bone  of  the  thumb 
during  the  movement  of  opposition.  The  other  longitudinal  furrow 
runs  downwards  from  the  wrist  internal  to  the  preceding,  and  meets 
the  lower  transverse  furrow.  It  is  due  to  the  movement  of  opposi- 
tion of  the  little  finger.  The  front  of  each  of  the  four  inner  fingers 
presents  three  transverse  furrows.  The  distal  pair  correspond 
with  the  interphalangeal  joints,  but  the  proximal  furrow  is  about 
^  inch  beyond  the  metacarpo-phalangeal  joint.  The  front  of  the 
thumb  presents  only  two  transverse  furrows. 

The  position  of  the  suj)erficial  palmar  arch  corres])onds  with  a  line 
drawn  across  the  j)alm  from  the  web  between  the  thumb  and  index 
finger  (the  thumb  being  abducted)  to  the  outer  side  of  the  pisiform 
bone.  This  line  is  slightly  arched,  with  the  convexity  towards  the 
fingers.     From   the  convexity  of   the   arch   the   three  compound 


346  A  MANUAL  OF  ANATOMY 

digital  arteries  pass  forwards  in  line  with  the  webs  of  the  fingers, 
and  they  lie  over  the  interosseous  spaces.  An  incision,  therefore, 
may  be  made  with  safety  in  the  palm  in  the  direction  of  the  middle 
line  of  a  finger,  but  it  should  not  be  carried  nearer  the  wrist  than 
the  line  indicating  the  position  of  the  superficial  palmar  arch. 
The  deep  palmar  arch  lies  about  |  inch  nearer  the  wrist  than  the 
superficial.  The  digital  arteries  are  placed  on  the  lateral  aspects 
of  the  fingers. 

On  the  back  of  the  hand  the  radial  tubercle  may  be  felt  about 
the  centre  of  the  lower  end  of  the  bone,  and  the  heads  of  the  meta- 
carpal bones,  which  form  the  knuckles,  are  conspicuous  when  the 
fingers  are  flexed.  Below  and  behind  the  styloid  process  of  the 
radius  there  is  a  well-marked  triangular  hollow,  the  base  of  which 
is  directed  upwards,  in  which,  by  sinking  the  finger  deeply,  pulsa- 
tion may  be  felt  in  the  second  part  of  the  radial  artery  in  the 
living  subject.  At  the  upper  part  the  tendons  of  the  radial 
extensors  of  the  wrist  may  also  be  felt.  The  hollow  is  bounded 
internally  by  a  prominence  formed  by  the  tendon  of  the  extensor 
longus  pollicis,  externally  by  a  prominence  due  to  the  tendons  of 
the  extensor  ossis  metacarpi  pollicis  and  extensor  brevis  pollicis,  and 
above  by  the  lower  end  of  the  radius.  The  scaphoid  and  trapezium 
lie  in  its  floor,  and  the  radial  vein  and  branches  of  the  radial  nerve 
are  in  its  roof.  This  hollow  is  known  as  the  anatomical  snuff-box 
(Cloquet). 

The  middle  line  of  the  hand,  from  and  towards  which  abduction 
and  adduction  take  place,  represents  a  longitudinal  line  drawn 
through  the  centre  of  the  middle  finger. 

Superficial  Fascia. — ^The  superficial  fascia,  especially  over  the 
hollow  of  the  palm,  is  lobulated,  the  lobules  being  separated  by 
fibrous  processes  which  pass  between  the  skin  and  the  central 
division  of  the  palmar  fascia. 

Palmaris  Brevis. — This  is  a  thin,  fiat,  subcutaneous  muscle,  of 
quadrilateral  outline,  and  usually  arranged  in  two  or  three  bundles, 
separated  by  fat. 

Origin. — (i)  The  front  of  the  anterior  annular  ligament  at  its 
lower  and  inner  part,  and  {2)  the  inner  margin  of  the  central  division 
of  the  palmar  fascia  at  its  upper  part. 

Insertion. — The  integument  of  the  inner  border  of  the  hand  at  its 
inner  part. 

Nerve-supply. — ^The  superficial  division  of  the  ulnar  nerve. 

Action. — ^To  draw  the  integument  into  which  it  is  inserted  towards 
the  middle  line  of  the  hand,  thus  giving  rise  to  a  wrinkled  depression 
on  the  inner  border  at  its  upper  part. 

The  muscle  lies  in  the  superficial  fascia  over  the  upper  part  of 
the  hypothenar  eminence,  and  covers  the  ulnar  vessels  and  nerve, 
which  it  guards  against  pressure. 

Superficial  Transverse  Ligament. — ^This  ligament  is  composed  of 
a  bundle  of  transverse  fibres,  contained  within  the  folds  of  skin  which 
form  the  clefts  of  the  four  inner  fingers. 


THE   UPPER  LIMB  347 

Palmar  Fascia. — The  palmar  fascia  is  arranged  in  three  divisions 
— central  and  two  lateral. 

The  central  division  is  triangular,  the  apex  being  towards  the 
wrist,  w^here  it  is  continuous  with  the  tendon  of  the  palmaris 
longus,  and  attached  to  the  front  of  the  anterior  annular  ligament 
close  to  its  lower  border.  The  superficial  fibres  of  this  division  are 
longitudinal,  and  the  deep  fibres  transverse,  the  latter  being  most 
conspicuous  between  the  diverging  digital  processes.  The  base  is 
directed  towards  the  roots  of  the  four  inner  fingers,  on  approaching 
which  the  fascia  divides  into  four  digital  processes.  These  diverge 
and  pass  to  join  the  sheaths  of  the  flexor  tendons  on  the  fronts  of  the 
fingers.  Each  process  gives  fibres  to  the  superficial  transverse  liga- 
ment and  skin  of  the  clefts  of  the  fingers.  Each  also  gives  off  a  deep 
expansion  at  either  side,  which  joins  the  transverse  metacarpal 
ligament  at  either  lateral  margin  of  the  head  of  a  metacarpal  bone. 
In  this  way  short  canals  are  formed  for  the  superficial  and  deep 
flexor  tendons  on  their  way  to  the  fronts  of  the  fingers.  Between  the 
diverging  digital  processes  three  intervals  are  left,  in  which  the  digital 
arteries  and  nerves  and  lumbricales  muscles  make  their  appearance  ; 
and,  as  stated,  the  transverse  fibres  are  here  conspicuous,  where  they 
lie  superficial  to  these  structures.  The  central  division  is  bound  to 
the  skin  by  fibrous  processes  which  enclose  spaces  containing  the 
lobules  of  the  superficial  fascia.  Its  deep  surface  is  related  to  the 
great  palmar  bursa.  At  either  side  it  gives  off  a  deep  septum 
which  joins  the  interosseous  fascia.  The  outer  septum  is  placed 
between  the  thenar  muscles  and  the  centre  of  the  palm,  where  the 
flexor  tendons  and  digital  vessels  and  nerves  lie,  and  it  is  pierced 
by  the  digital  nerves  for  the  sides  of  the  thumb  and  index  finger. 
The  inner  septum  is  placed  between  the  hypothenar  muscles  and 
the  centre  of  the  palm,  and  it  is  pierced  by  the  digital  branches  of 
the  ulnar  nerve,  and  by  a  portion  of  the  superficial  palmar  arch. 
In  this  way  a  large  central  fascial  canal  is  formed,  which  contains 
the  superficial  palmar  arch  and  its  digital  branches,  the  digital 
nerves,  the  superficial  and  deep  flexor  tendons,  and  the  lumbricales. 
On  either  side  of  this  central  canal  are  the  thenar  and  hypothenar 
canals,  containing  the  short  muscles  of  the  thumb  and  of  the 
little  finger.  The  central  division  of  the  palmar  fascia  serves  as 
an  important  protection  to  the  superficial  palmar  arch  and  the 
digital  arteries  and  nerves.  From  its  great  strength  and  capability 
of  resistance  it  has  an  important  bearing  on  the  course  taken  by 
pus  in  a  palmar  abscess. 

The  central  division  represents  the  expanded  portion  of  the 
tendon  of  an  original  superficial  flexor  muscle  of  the  fingers. 

The  external  or  thenar  division  is  thin,  and  covers  the  thenar 
muscles.  Superiorly  it  is  connected  with  the  tendon  of  the  palmaris 
longus  and  anterior  annular  ligament,  and  it  receives  an  accession 
of  fibres  from  the  tendon  of  the  extensor  ossis  metacarpi  pollicis. 
Inferiorly  it  blends  with  the  sheath  of  the  tendon  of  the  flexor  longus 
pollicis  on  the  front  of  the  thumb. 


348  A   MANUAL  OF  ANATOMY 

The  internal  or  hypothenar  division,  also  thin,  is  connected 
above  with  the  anterior  annular  ligament,  and  terminates  below 
over  the  muscles  inserted  into  the  inner  side  of  the  base  of  the  first 
phalanx  of  the  little  finger. 

Third  Part  of  the  Ulnar  Artery. — ^The  third  part  of  the  vessel  forms 
the  superficial  palmar  arch.  It  descends  for  a  little  under  cover  of 
the  palmaris  brevis,  and  then  turns  outwards  across  the  palm  in  an 
arched  manner.  About  the  middle  of  the  thenar  eminence  it  is 
joined  by  the  superficial  volar  of  the  radial,  or  by  a  branch  of  the 
arteria  radialis  indicis,  or,  failing  these,  by  a  branch  of  the  arteria 
princeps  pollicis,  and  so  the  arch  is  completed  externally.  Its  con- 
vexity is  directed  towards  the  fingers,  and  its  course  may  be  indicated 
by  a  line  drawn  across  the  palm  from  the  web  between  the  thumb 
and  index  finger  (the  thumb  being  abducted)  to  the  outer  side  of  the 
pisiform  bone,  the  line  being  slightly  arched,  with  the  convexity 
towards  the  fingers. 

Relations — Superficial. — The  integument,  the  palmaris  brevis  for 
a  short  distance  internally,  and  the  central  division  of  the  palmar 
fascia.  Deep. — From  within  outwards  it  rests  upon  the  opponens 
minimi  digiti,  the  digital  branches  of  the  ulnar  nerve,  the  flexor 
tendons,  and  the  digital  branches  of  the  median  nerve.  The  arch 
lies  within  the  great  palmar  bursa. 

Branches. — ^The  branches  of  the  arch  are  cutaneous  to  the  integu- 
ment of  the  palm,  muscular  to  the  adjacent  superficial  muscles,  the 
profunda  branch,  and  the  digital  branches. 

The  profunda  artery  is  given  off  from  the  commencement  of  the 
arch,  opposite  the  lower  border  of  the  anterior  annular  ligament. 
It  at  once  passes  deeply,  in  company  with  the  deep  division  of  the 
ulnar  nerve,  between  the  abductor  and  flexor  brevis  minimi  digiti, 
then  through  the  opponens  minimi  digiti,  and  it  terminates  by 
anastomosing  with  the  third  part  of  the  radial  artery,  thereby 
completing  the  deep  palmar  arch.  In  its  short  course  it  gives 
branches  to  the  hypothenar  muscles. 

The  digital  arteries  arise  from  the  convexity  of  the  arch,  and  are 
four  in  number.  They  are  destined  for  the  sides  of  the  inner  three 
and  a  half  fingers,  and  are  called  first,  second,  third,  and  fourth, 
from  within  outwards.  The  first  is  a  single  artery,  but  the  other 
three  are  compound,  each  ultimately  dividing  into  two.  The  first 
digital  artery,  of  small  size,  passes  downwards  and  inwards  over 
the  hypothenar  muscles,  to  which  it  gives  twigs,  and  then  it  passes 
along  the  inner  side  of  the  little  finger. 

The  second,  third,  and  fourth  digital  arteries,  which  are  compound, 
pass  downwards  over  the  fourth,  third,  and  second  interosseous 
spaces  to  near  the  clefts  between  the  little  and  ring,  ring  and  middle, 
and  middle  and  index  fingers,  where  each  divides  into  two  collateral 
digital  arteries,  which  pass  along  the  contiguous  sides  of  these  fingers. 
These  four  digital  arteries  account  for  the  blood-supply  of  the  sides 
of  the  inner  three  and  a  half  fingers.  The  outer  side  of  the  index 
finger  and  both  sides  of  the  thumb  are  supplied  by  the  arteria 


THE   UPPER  LIMB 


349 


Flexor  Carpi  Radialis  Klexor  Carpi  Ulnaris 

.Ulnar  Nerve 
Ulnar  Artery 


Superficial  Volar  Art 
Abductor  Pollicis 


Superf.  Head  of 
Flex.  Brev.  Poll. 


Add.  Obliq.  Po 

Add.  Trans.  .. 
Pollicis 
ist  Dorsal  _ 
Interosseou 


Vnterior  Annular 
Ligament 

__ Median  Nerve 

-Abd.  Min.  Dig. 
-Oppon.  Min.  Dig. 

-  Flexor  Brevis 
Minimi  Digiti. 

Superficial 
Palmar  Arch 


Fig.    195. — The  Palmar   Aspect  of  the  Hand. 
(The  Palmar  Fascia  has  l^een  removed.) 


350  A  MANUAL  OF  ANATOMY 

radialis  indicis  and  arteria  princeps  poUicis  of  the  radial.  As  the 
digital  arteries  pass  towards  the  fingers  they  lie  between  the  flexor 
tendons,  and  superficial  to  the  digital  nerves  and  lumbricales 
muscles.  Along  the  sides  of  the  fingers,  however,  the  digital 
nerves  are  superficial  to  the  arteries.  Just  before  the  outer  three 
digital  arteries  divide  into  their  collateral  branches  each  is  joined 
by  a  palmar  interosseous  artery  from  the  deep  palmar  arch,  and, 
it  may  be,  by  the  inferior  perforating  branches  of  the  dorsal  inter- 
osseous arteries.  The  innermost  digital  artery  receives  its  com- 
municating branch  from  the  innermost  palmar  interosseous  about 
the  centre  of  the  hand.  As  the  arteries  pass  along  the  sides 
of  the  fingers  they  anastomose  with  each  other  across  the  front 
of  the  phalanges  to  form  arches,  which  are  placed  on  the  proximal 
side  of  the  interphalangeal  joints.  Each  also  supplies  the  flexor 
tendons  with  their  sheaths,  and  gives  off  a  few  dorsal  branches. 
In  front  of  each  terminal  phalanx  the  arteries  of  each  finger  unite  to 
form  an  arch,  from  which  many  twigs  are  given  off  to  supply  the 
pulp  of  the  finger  and  matrix  of  the  nail. 

The  varieties  of  the  superficial  palmar  arch  will  be  afterwards 
described. 

Veins. — The  superficial  palmar  arch  is  accompanied  by  two 
venge  comites,  and  so  are  the  digital  arteries.  The  venae  comites 
of  the  digital  arteries  unite  at  the  clefts  of  the  fingers  to  form 
single  vessels,  and  these  end  in  the  venae  comites  of  the  superficial 
palmar  arch.  The  venae  comites  of  the  inner  part  of  the  arch  unite, 
and  so  do  those  of  the  inner  part  of  the  deep  palmar  arch,  and  in 
this  way  the  venae  comites  of  the  ulnar  artery  are  formed.  Those 
from  the  outer  side  of  the  superficial  arch  go  with  the  superficial 
volar  artery,  and,  with  those  from  the  outer  side  of  the  deep  arch 
which  accompany  the  second  part  of  the  radial  artery,  form  the 
radial  venae  comites. 

Median  Nerve  in  the  Hand. — ^The  median  nerve  enters  the  palm 
by  passing  beneath  the  anterior  annular  ligament,  where  it  lies 
within  the  great  palmar  bursa  along  with  the  superficial  and  deep 
flexor  tendons,  giving  off  articular  twigs  to  the  wrist- joint.  Close 
to  the  lower  border  of  the  ligament  it  presents  an  enlargement, 
and  breaks  up  into  two  divisions — external  and  internal.  The 
external  division  gives  off  a  muscular  branch  and  three  single 
digital  nerves.  The  muscular  branch  passes  outwards,  and  divides 
to  supply  the  abductor  poUicis,  opponens  pollicis,  and  superficial 
head  of  the  flexor  brevis  pollicis.  The  three  single  digital  nerves 
are  distributed  to  the  outer  and  inner  sides  of  the  thumb  and  the 
outer  side  of  the  index  finger,  and  the  latter  nerve  gives  a  branch 
to  the  first,  or  most  external,  lumbricalis.  The  internal  division 
breaks  up  into  two  compound  digital  nerves.  The  outer  of  these 
passes  to  near  the  cleft  between  the  index  and  middle  fingers, 
where  it  divides  into  two  collateral  digital  nerves  for  the  supply  of 
the  contiguous  sides  of  these  fingers.  In  its  course  it  gives  a  branch 
to   the  second  lumbricalis.     The  inner  passes  to  near  the  cleft 


THE   UPPER  LIMB 


351 


between  the  middle  and  ring  fingers,  where  it  also  divides  into 
two  collateral  digital  nerves,  which  supply  their  contiguous  sides. 
In  its  course  it  communicates  with  the  outer  digital  branch  of  the 
ulnar  nerve.  In  the  palm  the  digital  nerves  lie  beneath  the  super- 
ficial palmar  arch  and  its  digital  branches,  but  along  the  sides  of 
the  fingers  the  nerves  are  superficial  to  the  arteries.  Occasionally 
a  digital  artery  may  pass  through  a  digital  nerve.  On  the  sides 
of  the  fingers  the  nerves,  which  present  small  swellings,  called 
Pacinian  bodies,  give  branches  to  the  integument  of  the  palmar 
aspects  of  the  fingers,  and  the  metacarpo-phalangeal  and  inter- 
phalangeal  joints.     At  the  extremities  of  the  fingers  each  nerve 

Ulnar 
Median 
Anterior  Branch  of  ISIusculo-cutaneous 

Deep  Branch  of  Ulnar 

Branches  to  Hypothenar  Muscles 

Branches  to  ih  Thenar  Muscles  ._ 


Branch  to  ist  Lumbricalis  '^ 
Branch  to  2nd  Lumbricalis  '' 

Branch  connecting  Median  '' 
and  Ulnar 


Fig.   196. — DiAfiRAM  of  the  Nerves  of  the  Palm. 

ends  in  branches  for  the  pulp  and  matrix  of  the  nail.  The  digital 
nerves  also  give  branches  which  turn  backwards  to  the  dorsal  aspects 
of  the  fingers.  These,  for  the  most  part,  supply  the  integument 
as  follows  :  (i)  the  matrix  of  the  thumb-nail  ;  (2)  the  back  of  the 
terminal  phalanx  of  the  index  finger  ;  (3)  the  back  of  the  second 
and  terminal  phalanges  of  the  middle  finger  ;  and  (4)  the  back  of  the 
terminal,  and  distal  end  of  the  second,  phalanges  of  the  rmg  finger. 

Summary  of  the  Median  Nerve.— Muscular.— It  supplies  (i)  all  the  muscles 
on  the  front  of  the  forearm,  excejjt  the  flexor  carpi  ulnaris  and  inner  portion 
of  the  flexor  profundus  digitorunx;  (2)  two  and  a  half  muscles  of  the  thenar 
eminence,  namely,  the  abductor,  opponens,  and  superficial  head  of  the 
flexor  brevis,  pollicis  ;  and  (3)  the  outer  two  lumbricales.  Cutaneous.— 1 1 
supplies  the  outer  part  of  the  jjalm,  and  the  outer  three  and  a  half  digits. 
Articular.— It  supplies  branches  to  the  elbow-  and  wrist-joints,  as  well  as  to 
several  joints  of  the  hand. 


352  A   MANUAL  OF  ANATOMY 

Ulnar  Nerve  in  the  Hand. — ^The  ulnar  nerve  enters  the  hand  by 
passing  over  the  anterior  annular  ligament,  where  it  lies  on  the  inner 
side  of  the  ulnar  vessels,  and  is  overhung  by  the  pisiform  bone. 
It  then  breaks  up  into  two  divisions — superficial  and  deep.  The 
superficial  division  passes  downwards  beneath  the  palmaris  brevis, 
which  it  supplies,  and  it  ends  in  two  digital  nerves.  The  inner 
is  a  single  nerve,  and  is  distributed  to  the  inner  side  of  the  little 
finger.  The  outer,  which  is  compound,  passes  to  near  the  cleft 
between  the  ring  and  little  fingers,  where  it  divides  into  two  collateral 
digital  nerves  for  the  supply  of  their  contiguous  sides.  This  nerve 
communicates  with  the  innermost  digital  branch  of  the  median. 
The  distribution  of  the  nerves  on  the  fingers  corresponds  with 
that  of  the  median,  and  the  branches  which  turn  to  the  backs  of 
the  fingers  are  for  the  most  part  distributed  as  follows  :  (i)  to  the 
back  of  the  terminal,  and  distal  end  of  the  second,  phalanges  of  the 
ring  finger,  and  (2)  to  the  matrix  of  the  nail  of  the  little  finger. 
The  deep  division  of  the  ulnar  nerve,  along  with  the  profunda  branch 
of  the  ulnar  artery,  passes  between  the  abductor  and  flexor  brevis 
minimi  digiti,  and  then  through  the  opponens  minimi  digiti.  There- 
after it  accompanies  the  deep  palmar  arch,  above  which  it  lies,  to 
the  thenar  region,  and  it  has  an  extensive  muscular  distribution, 
as  follows  :  it  supplies  the  abductor,  flexor  brevis,  and  opponens, 
minimi  digiti,  the  inner  two  lumbricales,  the  seven  interossei,  and 
two  and  a  half  muscles  of  the  thenar  eminence — namely,  the  deep 
head  of  the  flexor  brevis  pollicis,  adductor  obliquus  pollicis,  and 
adductor  transversus  pollicis.  It  also  gives  articular  twigs  to  the 
wrist- joint,  and  several  of  the  joints  of  the  hand. 

Summary  of  the  Ulnar  Nerve. — Muscular. — In  the  forearm  it  supplies  the 
flexor  carpi  ulnaris  and  inner  portion  of  the  flexor  profundiis  digitorum ; 
and  in  the  hand  it  supplies  (i)  the  palmaris  brevis,  (2)  the  three  hypothenar 
muscles,  (3)  the  inner  two  lumbricales,  (4)  the  seven  interossei,  and  (5)  two 
and  a  half  muscles  of  the  thenar  eminence,  namely,  the  deep  head  of  the  flexor 
brevis,  adductor  obliquus,  and  adductor  transversus,  pollicis.  Cutaneous. — 
It  supplies  the  integument  of  ( i )  the  front  of  the  forearm  for  a  little  below 
the  centre,  and  internal  to  the  middle  line  ;  (2)  the  inner  portion  of  the  palm  ; 
and  (3)  the  inner  one  and  a  half  fingers.  Articular. — It  supplies  branches  to 
the  elbow-  and  wrist-joints,  and  several  of  the  joints  of  the  hand. 

Great  Palmar  Bursa. — ^This  bursa  has  two  compartments,  inner 
and  outer. 

The  inner  compartment,  which  is  large  and  loose,  invests  the 
superficial  and  deep  flexor  tendons  and  median  nerve  as  they  pass 
beneath  the  anterior  annular  ligament.  It  extends  upwards  into 
the  forearm  for  rather  more  than  an  inch  above  the  ligament,  and 
downwards  to  about  the  centre  of  the  palm.  It  is  shut  off  from  the 
synovial  sheaths  of  the  flexor  tendons  of  the  index,  middle,  and  ring 
fingers,  but  internally  it  is  prolonged  downwards  to  be,  as  a  rule, 
continuous  with  the  synovial  sheath  of  the  flexor  tendons  of  the 
little  finger. 

The  outer  compartment,  which  is  long  and  narrow,  invests  the 
tendon  of  the  flexor  longus  pollicis  beneath  the  anterior  annular 


THE   UPPER  LIMB 


353 


ligament,  and  reaches  upwards  to  the  same  height  as  the  inner 
compartment.  Interiorly  it  is  prolonged  uninterruptedly  along  the 
tendon  to  its  insertion,  so  that  it  is  continuous  with  its  synovial 
sheath  on  the  thumb.  The  disposition  of  the  great  palmar  bursa 
in  relation  to  the  thumb  and  little  finger  is  to  be  carefully  noted  in 
connection  with  whitlow  of  these  fingers.  It  will  be  evident  that 
pus  could  readily  burrow  upwards  from  the  thumb  and  little  finger 
into  the  lower  part  of  the  forearm,  passing  in  its  course  beneath  the 
anterior  annular  ligament. 


Anterior  Annular  Ligament 

Synovial  Sheath  of  Thumb 
Great  Palmar  Bursa 


Synovial  Sheath  of 
Little  Finger 


Fig.   197. 


-The  Great  Palmar  Bursa,   and  the  Synovial 
Sheaths  of  the  Flexor  Tendons. 


Sheaths  of  the  Flexor  Tendons.— As  the  superficial  and  deep  flexor 
tendons  pass  along  the  fronts  of  the  four  inner  fingers  each  pair  is 
contained  in  a  fibro-osseous  canal.  The  osseous  wall  is  formed  by 
the  palmar  aspects  of  the  first  and  second  phalanges,  and  the  fibrous 
wall  by  a  sheath.  This  sheath,  over  the  greater  parts  of  the  first 
and  second  phalanges,  is  thick  and  strong,  and  these  parts  of  it 
are  known  as  the  vaginal  ligaments.  The  fibres  of  these  ligaments 
run  transversely,  and  are  attached  to  the  rough  lateral  margins  of 
the  palmar  surfaces  of  the  phalangeal  shafts.  Opposite  the  joints, 
in  order  not  to  interfere  with  flexion,  the  vaginal  ligaments  are 
replaced  by  thin  membranes,  superadded  to  which  are  obliquely 

23 


354 


A   MANUAL  OF  ANATOMY 


Flexor  Profundus 


Flexor 
Sublimis 


decussating  fibres.  Each  fibro-osseous  canal  is  lined  by  synovial 
membrane,  which  is  reflected  over  the  contained  tendons  in  such  a 
manner  as  to  furnish  a  separate  investment  for  each.  The  synovial 
sheaths  of  the  index,  middle,  and  ring 
fingers  extend  into  the  palm  as  far  as 
the  heads  of  the  metacarpal  bones,  and 
they  have  no  connection  with  the  great 
palmar  bursa.  The  synovial  sheath  of 
the  little  finger,  however,  is  as  a  rule  con- 
tinuous with  the  large  inner  compartment 
of  that  bursa.  The  synovial  membranes 
of  the  sheaths  form  certain  bands,  called 
vincula  accessoria  tendinum,  which  are  of 
two  kinds — ligamenta  brevia  and  ligamenta 
longa.  The  ligamenta  brevia  are  two  in 
number — one  for  the  superficial  and  one 
for  the  deep  flexor  tendon.  They  are  broad, 
laterally  compressed,  triangular  bands  which 
connect  each  tendon,  close  to  its  insertion, 
with  the  distal  end  of  the  phalanx  above 
that  into  which  it  is  inserted.  The  liga- 
menta longa,  few  and  inconstant,  are  narrow 
cords  which  pass  between  the  tendons  and 
the  phalanges,  or  from  one  tendon  to  the 
other.  The  fibro-osseous  canal  for  the 
tendon  of  the  flexor  longus  pollicis  is 
similar  to  those  of  the  other  flexor  tendons, 
and  its  synovial  membrane  is  continuous 
with  the  outer  compartment  of  the  great  palmar  bursa. 

Lumbricales. — These  are  four  tapering  muscles  which  are  con- 
nected with  the  deep  flexor  tendons  in  the  palm,  and  they  receive 
numerical  names,  the  most  external  being  the  first.  The  first  and 
second  arise  each  from  the  outer  side  of  the  deep  flexor  tendon  for  the 
index  and  middle  fingers,  and  the  third  and  fourth  arise  from  the 
adjacent  sides  of  the  two  deep  flexor  tendons  between  which  each 
lies,  the  tendons  involved  being  those  for  the  middle,  ring,  and 
little  fingers.  Each  muscle  tapers  off,  and  ends  in  a  tendon  which, 
turning  round  the  outer  side  of  a  metacarpo-phalangeal  joint, 
expands,  and  is  inserted  into  the  outer  side  of  the  broad  expansion 
of  the  extensor  tendon  on  the  back  of  the  first  phalanx. 

N erve-supply — First. — ^The  digital  branch  of  the  median  to  the 
outer  side  of  the  index  finger.  Second. — ^The  digital  branch  of  the 
median,  which  divides  to  supply  the  contiguous  sides  of  the  index 
and  middle  fingers.  Third  and  Fourth. — The  deep  division  of  the 
ulnar  nerve. 

Action. — (i)  To  flex  the  metacarpo-phalangeal  joint,  and  (2) 
to  extend  the  interphalangeal  joints. 

Anterior  Annular  Ligament. — This  is  a  strong  fibrous  band 
which  bridges  over  the  concavity  on  the  palmar  aspect  of  the  carpus, 


Fig.    198. — The   Flexor 
Tendons  of  a  Finger. 


THE   UPPER  LIMB  355 

and  converts  it  into  a  fibro-osseous  canal.  Externally  it  is  attached 
to  the  tuberosities  of  the  scaphoid  and  trapezium,  and  internally  to 
the  pisiform  and  hook  of  the  unciform.  Its  upper  border  is  con- 
tinuous with  the  deep  fascia  of  the  front  of  the  forearm  ;  its  lower 
border  is  connected  with  the  palmar  fascia  ;  at  its  upper  and  inner 
part  it  receives  an  expansion  from  the  tendon  of  the  flexor  carpi 
ulnaris  ;  and  near  its  lower  border  it  gives  partial  insertion  to  the 
tendon  of  the  palmaris  longus.  The  ligament  is  crossed  by  the  last- 
mentioned  tendon  and  the  ulnar  vessels  and  nerve,  the  latter 
structures  lying  close  to  the  pisiform  bone,  where  they  are  overhung 
by  it,  and  overlapped  by  a  slip  from  the  flexor  carpi  ulnaris.  At 
either  side  the  ligament  affords  origin  to  muscles  of  the  thenar  and 
hypothenar  groups.  The  fibro-osseous  canal  formed  by  the  liga- 
ment and  front  of  the  carpus  gives  passage  to  the  tendons  of  the 
flexor  sublimis  and  flexor  profundus  digitorum,  the  tendon  of  the 
flexor  longus  pollicis,  and  the  median  nerve.  The  tendon  of  the 
flexor  carpi  radialis  does  not  pass  through  this  canal,  but  traverses 
a  special  compartment  in  the  outer  part  of  the  ligament  as  it  passes 
through  the  groove  on  the  front  of  the  trapezium,  where  it  is  invested 
by  a  special  synovial  sheath. 

Thenar  Muscles. — The  short  muscles  of  the  thumb  are  five  in 
number,  namely,  the  abductor,  opponens,  and  flexor  brevis,  pol- 
licis, the  adductor  obliquus  pollicis,  and  the  adductor  transversus 
pollicis. 

1.  Abductor  Pollicis — Origin. — (i)  The  front  of  the  anterior 
annular  ligament ;  (2)  the  tuberosity  of  the  scaphoid ;  and  (3)  the 
tuberosity  of  the  trapezium. 

Insertion. — (i)  The  outer  side  of  the  base  of  the  first  phalanx  of 
the  thumb,  in  association  with  the  superficial  head  of  the  flexor 
brevis  pollicis  ;  and  (2)  the  outer  margin  of  the  tendon  of  the  ex- 
tensor longus  pollicis  on  the  back  of  the  first  phalanx. 

Nerve-supply. — The  median  nerve. 

The  muscle,  which  is  triangular,  is  directed  downwards  and  out- 
wards. 

Action. — (i)  To  abduct  the  thumb,  and  (2)  to  assist  in  flexing  its 
first  phalanx,  the  result  being  that  the  thumb  is  drawn  forwards  and 
a  little  inwards.     It  also  assists  in  extending  the  distal  phalanx. 

The  muscle  rests  upon  the  opponens  pollicis,  and  the  superficial 
head  of  the  flexor  brevis  pollicis  lies  on  its  inner  side. 

2.  Opponens  Pollicis — Origin. — (i)  The  front  of  the  anterior 
annular  ligament,  and  (2)  the  tuberosity  of  the  trapezium. 

Insertion. — The  outer  border  of  the  shaft  of  the  metacarpal  bone 
of  the  thumb,  and  the  adjacent  part  of  its  palmar  surface. 

Nerve-supply. — The  median  nerve. 

The  muscle,  which  is  triangular,  is  directed  downwards  and 
outwards. 

Action. — To  flex  the  first  metacarpal  bone,  the  result  being  that 
the  thumb  is  drawn  forwards  and  inwards  across  the  palm,  so  as  to 
oppose  its  tip  to  the  tips  of  the  four  inner  fingers. 

23—2 


356  A  MANUAL  OF  ANATOMY 

The  muscle  supports  the  abductor  polhcis,  and  has  the  superficial 
head  of  the  flexor  brevis  poUicis  along  its  inner  border. 

3.  Flexor  Brevis  Pollicis. — This  muscle  arises  by  two  heads — a 
large  superficial  or  outer,  and  a  small  deep  or  inner.  The  super- 
ficial head  arises  from  the  outer  two-thirds  of  the  lower  border  of 
the  anterior  annular  ligament,  and  the  tuberosity  of  the  trapezium. 
The  deep  head  (interosseus  primus  volaris)  arises  from  the  proximal 
extremity  of  the  first  metacarpal  bone  on  its  inner  aspect. 

Insertion. — ^The  superficial  head,  along  with  the  abductor  pollicis, 
is  inserted  into  the  outer  side  of  the  base  of  the  first  phalanx  of 
the  thumb,  a  sesamoid  bone  being  contained  within  it.  The  deep 
head  joins  the  adductor  obliquus  pollicis,  and,  along  with  it,  is 
inserted  into  the  inner  side  of  the  base  of  the  first  phalanx  of  the 
thumb. 

Nerve-supply. — ^The  superficial  head  is  supplied  by  the  median 
nerve,  and  the  deep  head  by  the  deep  division  of  the  ulnar 
nerve. 

Action. — To  flex  the  metacarpo-phalangeal  joint  of  the  thumb, 
and  so  to  assist  in  opposition. 

4.  Adductor  Obliquus  Pollicis — Origin. — By  several  bundles  from 
(i)  the  fronts  of  the  bases  of  the  second  and  third  metacarpal  bones ; 
(2)  the  fronts  of  the  trapezoid  and  os  magnum ;  and  (3)  the  sheath 
of  the  tendon  of  the  flexor  carpi  radialis. 

Insertion. — ^The  muscle,  having  received  the  small  deep  head  of 
the  flexor  brevis  pollicis,  is  inserted,  along  with  the  adductor  trans- 
versus  pollicis,  into  the  inner  side  of  the  base  of  the  first  phalanx 
of  the  thumb,  a  sesamoid  bone  being  contained  within  it. 

In  its  course  the  muscle  detaches,  from  its  outer  side,  a  large 
fleshy  bundle,  which  passes  outwards  behind  the  tendon  of  the 
flexor  longus  pollicis  and  joins  the  superficial  head  of  the  flexor 
brevis  pollicis. 

Nerve- supply. — ^The  deep  division  of  the  ulnar  nerve. 

The  muscle  is  directed  downwards  and  outwards. 

Action. — ^To  adduct  the  thumb  and  assist  in  opposition. 

The  muscle  has  the  superficial  head  of  the  flexor  brevis  pollicis  on 
its  outer  side,  the  tendon  of  the  flexor  longus  pollicis  lying  between 
the  two,  and  the  adductor  transversus  pollicis  along  its  inner  and 
lower  aspect,  the  radial  artery  passing  between  the  two. 

5.  Adductor  Transversus  Pollicis — Origin. — ^The  distal  two- thirds 
of  the  anterior  border  of  the  shaft  of  the  third  metacarpal  bone. 

Insertion. — (i)  The  inner  side  of  the  base  of  the  first  phalanx  of  the 
thumb,  along  with  the  adductor  obliquus  pollicis  and  deep  head  of 
the  flexor  brevis  pollicis  ;  and  (2)  the  inner  margin  of  the  tendon  of 
the  extensor  longus  pollicis  on  the  back  of  that  phalanx. 

Nerve-siipply. — ^The  deep  division  of  the  ulnar  nerve. 

The  muscle,  which  is  triangular,  is  directed  outwards. 

Action. — ^To  adduct  the  thumb  and  assist  in  opposition.  It  also 
assists  in  extending  the  distal  phalanx. 

The  tendon  of  the  flexor  longus  pollicis  on  its  way  to  its  insertion 


THE   UPPER  LIMB 


357 


has  on  its  outer  side  the  superficial  head  of  the  flexor  brevis  polhcis, 
and  on  its  inner  side  the  adductor  obhquus  polhcis. 

Hypothenar  Muscles. — The  short  muscles  of  the  little  finger  are 
three  in  number,  namely,  the  abductor,  flexor  brevis,  and  opponens, 
minimi  digiti. 


Flexor  Carpi  Ulnari'i 

Flexor  Sublimis  Digitorum 


Anterior  Annular, 
Ligament 

Abductor  Minimi 

Digiti 
Flexor  Brevis  Minimi ——— . 

Digiti  M/F  / 

Opponens  Minimi Bt  III  m ^, 

Digiti 


Flexor  Carpi  Radialis 

Flexor  Longus  PoUicis 

Abductor  PoUicis  (cut) 

Opponens  PoUicis 


Superficial  Head  of  Flexor 


3rd  Palmar  Inteross 

4th  Dorsal  Inteross. 


2nd  Palmar  Inteross 

3rd  Dorsal  Inteross.^— " 
2nd  Dorsal  Inteross.-'" 


Flexor  Longus 
PoUicis 

ist  Dorsal 
Interosseous 

~-  ist  Palmar 
Interosseous 


^.ist  Lumbricalis 


Fig.  199. — The  Thenar  and  Hypothenar  Muscles. 


I.  Abductor  Minimi  Digiti — Origin.— The  lower  part  of  the  pisi- 
form bone. 

Insertion. — (i)  The  inner  side  of  the  base  of  the  first  phalanx  of 
the  little  finger,  in  common  with  the  flexor  brevis  minimi  digiti ; 
and  (2)  the  inner  margin  of  the  tendon  of  the  extensor  minimi  digiti 
on  the  back  of  the  phalanx. 

Nerve-supply. — The  deep  division  of  the  ulnar  nerve. 


358  A   MANUAL  OF  ANATOMY 

Aciion. — (i)  To  abduct  the  little  finger,  and  flex  its  metacarpo- 
phalangeal joint ;  and  (2)  to  assist  in  extending  the  second  and  third 
phalanges. 

2.  Flexor  Brevis  Minimi  Digiti — Origin. — (i)  The  inner  surface 
of  the  hook  of  the  unciform  bone  close  to  its  tip,  and  (2)  the  front 
of  the  adjacent  portion  of  the  anterior  annular  ligament. 

Insertion.— The  inner  side  of  the  base  of  the  first  phalanx  of  the 
little  finger,  in  common  with  the  abductor  minimi  digiti. 

Nerve-supply. — The  deep  division  of  the  ulnar  nerve. 

Action. — To  flex  the  metacarpo-phalangeal  joint  of  the  little  finger. 

This  muscle  is  of  small  size,  and  lies  on  the  outer  side  of  the  ab- 
ductor minimi  digiti,  from  which  it  is  separated,  close  to  its  origin, 
by  the  profunda  branch  of  the  ulnar  artery  and  deep  division  of 
the  ulnar  nerve. 

3.  Opponens  Minimi  Digiti — Origin. — (i)  The  inner  surface  of 
the  hook  of  the  unciform  bone  underneath  the  preceding  muscle, 
and  (2)  the  adjacent  part  of  the  anterior  annular  ligament. 

Insertion. — The  inner  margin  of  the  shaft  of  the  fifth  metacarpal 
bone. 

Nerve-supply. — The  deep  division  of  the  ulnar  nerve. 

Action. — ^To  flex  and  adduct  the  fifth  metacarpal  bone. 

The  muscle  supports  the  abductor  and  flexor  brevis  minimi  digiti, 
and  its  deep  surface  is  related  to  the  interosseous  muscles  of  the 
fourth  space.  The  deep  branches  of  the  ulnar  artery  and  nerve 
pass  through  it  on  their  way  to  the  deep  part  of  the  palm. 

Third  Part  of  the  Radial  Artery. — The  third  part,  which  forms  the 
greater  portion  of  the  deep  palmar  arch,  extends  from  the  upper 
part  of  the  first  interosseous  space  to  about  the  base  of  the  fifth 
metacarpal  bone,  where  it  is  joined  by  the  profunda  branch  of  the 
ulnar.  It  enters  the  palm  by  passing  between  the  two  heads  of  the 
abductor  indicis,  and  then  it  crosses  the  palm,  resting  upon  the 
bases  of  the  second,  third,  and  fourth  metacarpal  bones,  and  the 
adjacent  interosseous  muscles.  In  its  course  it  describes  a  slight 
arch,  the  convexity  of  which  is  directed  towards  the  fingers,  and  it  is 
about  ^  inch  nearer  the  wrist  than  the  superficial  palmar  arch. 
The  deep  division  of  the  ulnar  nerve  lies  close  above  it.  The  third 
part  of  the  vessel  is  at  first  under  cover  of  the  adductor  obliquus 
poUicis  ;  it  then  passes  between  that  muscle  and  the  adductor 
transversus  pollicis ;  and  thereafter  it  lies  beneath  the  superficial 
and  deep  flexor  tendons  and  lumbricales,  where  it  forms  the  deep 
palmar  arch. 

Branches. — ^These  are  the  arteria  princeps  pollicis,  arteria  radialis 
indicis,  three  palmar  interosseous,  recurrent,  and  superior  per- 
forating, the  last  three  coming  from  the  deep  palmar  arch. 

The  arteria  princeps  pollicis  arises  from  the  vessel  immediately 
after  it  emerges  from  between  the  two  heads  of  the  abductor  indicis, 
and  it  passes  downwards  along  the  first  metacarpal  bone,  lying  upon 
the  abductor  indicis  and  under  cover  of  the  adductor  obliquus  pollicis. 
On  reaching  the  head  of  the  bone  it  divides,  under  cover  of  the  tendon 


THE  UPPER  LIMB 


359 


of  the  flexor  longus  pollicis,  into  two  collateral  digital  arteries  for 
the  sides  of  the  thumb,  which  appear  on  either  side  of  the  long  flexor 
tendon,  between  the  superficial  head  of  the  flexor  brevis  pollicis  and 
adductor  obliquus  pollicis.  Their  distribution  is  similar  to  that  of 
the  other  digital  arteries.  The  arteria  princeps  pollicis  may  give 
a  branch  to  complete  the  superficial  palmar  arch. 

The  arteria  radialis  indicis  passes  downwards  along  the  outer 
side  of  the  second  metacarpal  bone,  lying  upon  the  abductor  indicis 
and  under  cover  of  the  adductor  obliquus,  and  adductor  transversus 


Anterior  Radial  Carpal 


Anterior  Ulnar  Carpal 

^. Ulnar  Artery 


Radial  Artery 


Superficial  V^olar 


Princeps^ 
Pollicis    " 


-Deep  Branch  of  Ulnar 
_^  Recurrent  Branches 

™  _  Deep  Palmar  Arch 

1st  Digital  Artery 

in     tiom  Superficial 

'      Palmar  Arch 


Radialis  Indicis  / 

ist  Palmar  Interosseus 


4th  Digital  Artery  from  Superficial  Palmar  Arch 


Fig.   200. — The  Radial  Artery  in  the  Palm  (Deep  Palmar  Arch) 
(after  Spalteholz). 

pollicis,  and  it  becomes  the  digital  artery  of  the  outer  side  of  the 
index  finger.  It  may  give  a  branch  to  complete  the  superficial 
palmar  arch. 

Branches  of  the  Deep  Palmar  Arch.— The  palmar  interosseous 
arteries,  three  in  number,  arise  from  the  convexity  of  the  arch, 
and  i>ass  downwards  over  the  second,  third,  and  fourth  inter- 
osseous spaces.  Near  the  clefts  of  the  corresponding  fingers,  they 
terminate  by  joining  the  three  compound  digital  arteries  of  the 
superficial  palmar  arch.  The  innermost  palmar  interosseous,  as  a 
rule,  gives  off  a  communicating  branch  to  join  the  single  digital 


36o  A  MANUAL  OF  ANATOMY 

artery  from  the  superficial  arch  to  the  inner  side  of  the  Httle  finger, 
the  junction  taking  place  about  the  centre  of  the  palm.  In  those 
cases  where  the  digital  arteries  from  the  superficial  arch  are  awanting. 
the  palmar  interosseous  arteries  may  take  their  place. 

The  recurrent  branches,  few  and  small  in  size,  arise  from  the 
concavity  of  the  arch,  and  pass  upwards  to  take  part  in  the  anterior 
carpal  rete. 

The  superior  perforating  arteries,  three  in  number,  pass  through 
the  upper  ends  of  the  inner  three  interosseous  spaces  between  the 
two  heads  of  the  corresponding  dorsal  interosseous  muscles,  and  on 
the  back  of  the  hand  they  join  the  dorsal  interosseous  arteries. 

Varieties  of  the  Ulnar  and  Radial  Arteries  in  the  Hand. — i .  The  ulnar  artery 

may  be  deficient  in  the  number  of  digital  branches  furnished  by  the  superficial 
palmar  arch,  or  the  vessel  may  end  as  the  profunda  artery,  in  which  latter  case 
there  would  be  no  superficial  arch.  Under  these  circumstances  the  deficiencies 
are  usually  supplied  by  the  palmar  interosseous  branches  of  the  deep  arch, 
but  sometimes  by  a  large  median  and  large  superficial  volar  artery. 

2.  The  radial  artery  may  be  deficient  in  its  normal  branches,  and  the  arteria 
princeps  poUicis  and  arteria  radialis  indicis  may  arise  from  the  superficial 
arch,  from  a  median,  or  from  a  superficial  volar,  artery. 

Veins. — The  deep  palmar  arch  is  accompanied  by  two  vense 
comites,  which  receive  tributaries  corresponding  to  the  branches 
of  the  arch.  The  destination  of  these  venae  comites  on  either  side 
has  been  already  described  in  connection  with  the  superficial 
palmar  arch. 

Summary  of  the  Palmar  Arches. — The  superficial  palmar  arch  is  formed 
mainly  by  the  ulnar  artery,  being  completed  by  the  superficial  volar  of  the 
radial,  or,  if  this  fails,  by  a  branch  from  the  arteria  radialis  indicis,  or  arteria 
princeps  polUcis.  Its  digital  branches  lie  over  the  interosseous  spaces,  so  that, 
to  avoid  them,  incisions  in  the  palm  should  be  made  in  line  with  the  centre  of 
a  finger,  and  should  not  be  prolonged  farther  upwards  than  the  line  indicating 
the  position  of  the  superficial  palmar  arch.  On  the  fingers  the  digital  arteries 
are  placed  laterally,  so  that  in  cases  of  whitlow  an  incision  should  be  made 
along  the  middle  line  of  a  finger.  The  superficial  palmar  arch  is  sometimes 
joined  by  a  large  median  artery,  which  is  a  branch  of  the  anterior  interosseous 
high  up  in  the  forearm.  In  such  cases,  if  the  arch  were  to  be  punctured,  and 
if  the  haemorrhage  could  not  be  arrested  by  the  graduated  compress,  it  is 
evident  that  ligature  neither  of  the  ulnar  nor  radial  artery  would  suffice.  In 
order  to  arrest  the  circulation  through  a  large  median  artery  the  ligature 
would  require  to  be  placed  on  the  brachial  artery. 

The  deep  palmar  arch  is  formed  mainly  by  the  radial  artery,  and  is  com- 
pleted by  the  profunda  branch  of  the  ulnar.  It  lies  about  |  inch  above  the 
superficial  arch. 

BACK  OF  THE  FOREARM  AND  HAND. 

The  cutaneous  nerves,  already  described,  are  as  follows  :  the 
posterior  branch  of  the  musculo- cutaneous  and  the  lower  external 
cutaneous  branch  of  the  musculo-spiral  to  the  outer  part,  and  the 
posterior  division  of  the  internal  cutaneous  to  the  inner  part. 

The  deep  fascia  of  the  back  of  the  forearm  has  been  described  in 
connection  with  the  anterior  aspect,  and  the  posterior  annular 
ligament  will  be  presently  referred  to. 


THE   UPPER  LIMB  361 

Muscles  of  the  Outer  Side  of  the  Forearm. — ^These  are  three 
in  number,  namel}',  the  brachio-radialis,  extensor  carpi  radialis 
longior,  and  extensor  carpi  radialis  brevior. 

1.  Brachio-radialis  (supinator  radii  longus) — Origin. — (i)  The 
upper  two-thirds  of  the  external  supracondylar  ridge  of  the  humerus, 
and  (2)  the  front  of  the  external  intermuscular  septum  over  a 
corresponding  extent. 

Insertion. — ^The  outer  side  of  the  radius  close  above  the  base  of 
the  styloid  process. 

Nerve-sitpply. — The  musculo-spiral  nerve. 

Action. — Though  called  a  supinator,  the  muscle  is  a  flexor  of  the 
forearm,  acting  most  directly  when  the  limb  is  in  a  state  of  semi- 
pronation.  An  important  use  of  the  muscle  is  to  maintain  the 
forearm  in  the  flexed  position,  as  in  holding  a  book.  When  the 
forearm  is  fully  pronated  the  muscle  is  a  feeble  supinator,  but  only 
to  the  extent  of  semisupination.  When  the  forearm  is  fully  supi- 
nated  it  produces  semipronation. 

The  muscle  presents  a  fleshy  belly  to  near  the  middle  of  the  fore- 
arm. Thereafter  it  is  replaced  by  a  flat  tendon,  which  first  appears 
on  the  deep  surface  of  the  muscle.  Superiorly  the  surfaces  are 
directed  outwards  and  inwards,  but  afterwards  they  look  forwards 
and  backwards. 

2.  Extensor  Carpi  Radialis  Longior — Origin. — (i)  The  lower 
third  of  the  external  supracondylar  ridge  of  the  humerus,  and 
(2)  the  front  of  the  external  intermuscular  septum  for  a  correspond- 
ing extent. 

Insertion. — The  back  of  the  base  of  the  second  metacarpal  bone 
over  its  outer  half,  a  small  bursa  lying  beneath  the  tendon. 

Nerve-supply. — The  musculo-spiral  nerve. 

Action. — (i)  To  extend  the  wrist-joint,  and  (2)  to  assist  in  ex- 
ternal lateral  flexion  (abduction)  of  that  joint. 

The  muscle  presents  a  fleshy  belly  to  near  the  middle  of  the  fore- 
arm, and  thereafter  a  tendon  which  descends  at  first  upon,  and 
then  on  the  outer  side  of,  the  tendon  of  the  extensor  carpi  radialis 
brevior.  These  two  tendons  pass  beneath  the  posterior  annular 
ligament,  and  occupy  the  outermost  groove  on  the  back  of  the 
lower  end  of  the  radius.  The  surfaces  of  the  muscle  are  at  first 
directed  outwards  and  inwards,  and  then  forwards  and  backwards. 

3.  Extensor  Carpi  Radialis  Brevior — Origin. — (i)  The  external 
epicondyle  of  the  humerus  by  the  common  tendon  ;  (2)  the  external 
lateral  ligament  of  the  elbow-joint ;  and  (3)  the  intermuscular  septa 
between  it  and  adjacent  muscles. 

Insertion.— The  back  of  the  base  of  the  third  metacarpal  bone 
over  its  outer  half,  and  often  by  a  small  slip  into  the  back  of  the 
base  of  the  second  metacarpal  over  its  inner  part.  A  small  bursa  is 
placed  beneath  the  tendon. 

Nerve-supply. — The  posterior  interosseous  nerve. 

Action. — (i)  To  extend  the  wrist-joint,  and  (2)  to  assist  in 
external  lateral  flexion  (abduction)  of  that  joint. 


362  A   MANUAL  OF  ANATOMY 

The  tendon  appears  about  the  centre  of  the  forearm,  and  becomes 
free  from  fleshy  fibres  in  the  lower  third.  It  descends  beneath  the 
tendon  of  the  long  radial  extensor,  except  near  its  insertion,  where 
it  lies  internal  to  that  tendon.  It  accompanies  the  long  tendon 
beneath  the  posterior  annular  ligament,  and  passes  with  it  through 
the  outermost  groove  on  the  back  of  the  lower  end  of  the  radius. 

Muscles  of  the  Back  of  the  Forearm. — ^These  are  arranged  in  two 
layers — superficial  and  deep. 

Superficial  Layer. — ^The  muscles  of  this  layer,  which  are  serially 
continuous  with  those  of  the  outer  side  of  the  forearm,  are  four 
in  number,  namely,  the  extensor  communis  digitorum,  extensor 
minimi  digiti,  extensor  carpi  ulnaris,  and  anconeus.  The  first  three 
have  a  common  tendon  of  origin,  which  they  share  with  the  extensor 
carpi  radialis  brevior. 

I.  Extensor  Communis  Digitorum — Origin. — (i)  The  external  epi- 
condyle  of  the  humerus  by  the  common  tendon  ;  (2)  the  deep  fascia  ; 
and  (3)  the  intermuscular  septa  between  it  and  adjacent  muscles. 

Insertion. — ^The  muscle  ends  in  four  tendons,  which  pass  beneath 
the  posterior  annular  ligament  to  the  dorsum  of  the  hand.  Here 
they  diverge  and  pass  to  the  four  inner  fingers,  that  for  the  index 
finger  being  accompanied  internally  by  the  tendon  of  the  extensor 
indicis.  Having  crossed  the  metacarpo-phalangeal  joints,  where 
they  give  fibres  to  their  lateral  ligaments,  the  tendons  form 
broad  expansions  covering  the  backs  of  the  first  phalanges,  which 
give  insertion  to  the  lumbricales  and  interossei.  Towards  the 
distal  end  of  the  first  phalanx  the  expansion  divides  into  three 
parts — central  and  two  lateral.  The  central  part  is  inserted  into 
the  back  of  the  base  of  the  second  phalanx.  The  two  lateral  parts 
unite  on  the  back  of  the  second  phalanx,  and  are  inserted  into  the 
back  of  the  base  of  the  distal  phalanx.  The  index  and  middle 
finger  tendons  are  connected  by  a  weak  band  of  fibres.  The  ring- 
finger  tendon  is  connected  by  a  strong  band  of  fibres  with  the 
tendon  on  either  side  of  it,  which  explains  the  very  limited  amount 
of  extension  of  which  the  ring-finger  is  capable,  unless  the  middle 
and  little  fingers  are  extended  along  with  it.  The  little  finger 
tendon  may  divide  into  two  parts,  one  joining  the  ring-finger  tendon 
and  the  other  the  tendon  of  the  extensor  minimi  digiti. 

Nerve-supply. — ^The  posterior  interosseous  nerve. 

Action. — (i)  To  extend  the  first  phalanges  of  the  four  inner 
fingers,  and  also  the  second  and  third  phalanges  slightly,  these 
being  extended  principally  by  the  interossei  and  lumbricales  ; 
and  (2)  to  assist  in  extension  of  the  wrist-joint. 

The  common  extensor  tendons,  along  with  that  of  the  extensor 
indicis,  in  passing  beneath  the  posterior  annular  ligament,  occupy 
the  broad  innermost  groove  on  the  back  of  the  radius. 

2.  Extensor  Minimi  Digiti — Origin. — (i)  The  external  epicondyle 
of  the  humerus  by  the  common  tendon;  (2)  the  deep  fascia;  and 
(3)  the  intermuscular  septum  on  either  side. 

Insertion. — Having  passed  beneath  the  posterior  annular  liga- 


THE  UPPER  LIMB 


363 


ment,  where  it  occupies  the  groove  between  the  radius  and  ulna, 
the  tendon  divides  into  two  parts,  the  outer  part  being  joined  by  the 
common  extensor  tendon  to  the  httle  finger,  or  by  its  inner  division. 
Both  parts  end  in  a  broad  expansion  on  the  back  of  the  first  phalanx, 


Biceps 


Brachio-radialis 


\ 


Lstensor  Carpi 
Ulnaris 


Extensor  Carpi  Radialis  Longior 


Extensor  Carpi  Radialis  Brevior 


Extensor  Ossis  Metacarpi  PoUicis 
Extensor  Brevis  Pollicis 
Extensor  Longus  Pollicis 


ten-.or  C-irpi  Ulnaris 

-     Extensor  Minin  1  Digiti 

_    Posterior  Annular  Ligament 

-  Extensor  Carpi  Radialis 
Brevior 

Extensor  Minimi  Digiti 

(in  two  parts) 
Connecting  Band 


Fig.  201.— The  Muscles  of  the  Radial  Side  and  Back  of  the 
Forearm, 

and  the  ultimate  insertion  is  as  in  the  case  of  the  common  extensor 
tendons. 

Nerve-supply. — The  posterior  interosseous  nerve. 

Action.— The  muscle  is  the  special  extensor  of  the  little  finger. 


364  A   MANUAL  OF  ANATOMY 

as  in  inserting  that  finger  into  the  ear  canaL     It  also  acts  as  a 
feeble  auxiliary  extensor  of  the  wrist-joint. 

3.  Extensor  Carpi  Ulnaris — Origin. — (i)  The  external  epicondyle 
of  the  humerus  by  the  common  tendon  ;  (2)  the  deep  fascia  ; 
(3)  the  intermuscular  septum  on  either  side ;  and  (4)  the  upper 
two-thirds  of  the  posterior  border  of  the  ulna  by  an  aponeurosis 
which  is  common  to  it,  the  flexor  carpi  ulnaris,  and  the  flexor 
profundus  digitorum. 

Insertion. — ^The  tubercle  on  the  inner  side  of  the  base  of  the 
fifth  metacarpal  bone. 

Nerve-supply. — ^The  posterior  interosseous  nerve. 

Action. — (i)  To  extend  the  wrist-joint,  and  (2)  to  assist  in 
internal  lateral  flexion  (adduction)  of  that  joint. 

The  muscle  rests  upon  the  inner  half  of  the  posterior  surface  of 
the  shaft  of  the  ulna,  and  its  tendon,  in  passing  beneath  the  posterior 
annular  ligament,  occupies  the  groove  on  the  back  of  the  ulna. 

4.  Anconeus — Origin. — ^The  back  of  the  external  epicondyle  of 
the  humerus  at  its  lower  part. 

Insertion. — The  outer  surface  of  the  olecranon  process,  and  the 
upper  third  of  the  posterior  surface  of  the  shaft,  of  the  ulna. 

The  muscle,  which  is  continuous  with  the  internal  head  of  the 
triceps,  is  triangular,  the  upper  fibres  being  short  and  transverse, 
whilst  the  others  pass  obliquely  downwards  and  inwards. 

Nerve-supply. — The  musculo-spiral  nerve,  by  means  of  a  long 
branch  which  descends  in  the  internal  head  of  the  triceps,  and 
enters  the  muscle  on  its  deep  surface  near  the  upper  border. 

Action. — ^To  assist  the  inner  head  of  the  triceps  in  extending  the 
elbow. 

The  posterior  interosseous  recurrent  artery  ascends  beneath  the 
muscle  to  the  back  of  the  external  epicondyle. 

The  posterior  interosseous  nerve  will  be  found  described  on 
p.  336,  and  the  corresponding  artery  on  p.  339. 

Deep  Layer. — ^There  are  five  muscles  in  this  layer,  namely,  the 
supinator  radii  brevis,  extensor  ossis  metacarpi  pollicis,  extensor 
brevis  pollicis,  extensor  longus  pollicis,  and  extensor  indicis. 

I.  Supinator  Radii  Brevis — Origin. — (i)  The  external  lateral 
ligament  of  the  elbow- joint ;  (2)  the  orbicular  ligament  of  the 
radius ;  (3)  the  back  part  of  the  bicipital  hollow,  and  the  supinator 
ridge,  of  the  ulna  ;  and  (4)  the  aponeurosis  covering  the  upper 
part  of  the  muscle. 

Insertion. — The  shaft  of  the  radius  on  its  anterior,  outer,  and 
posterior  aspects  over  about  the  upper  third. 

Anteriorly  the  muscle  descends  as  low  as  the  anterior  oblique  line, 
externally  as  low  as  the  insertion  of  the  pronator  radii  teres,  and 
posteriorly  as  low  as  the  posterior  oblique  line.  It  closely  invests 
the  radius  over  about  its  upper  third,  except  on  its  inner  aspect. 

Nerve-supply. — The  posterior  interosseous  nerve. 

Action. — To  supinate  the  radius  upon  the  ulna. 

The  muscle  is  pierced  by  the  posterior  interosseous  nerve,  and, 


THE  UPPER  LIMB 


36: 


Tricep- 


Anconeus  - 


Extensor  Communis 
Digitorum 


Extensor  Minimi  Digiti 


Extensor  Carpi  Ulnaris . 


Dorsal  Branch  of 
Ulnar  Nerve 

Posterior  Annular 
Ligament 


Extensor  Minimi  Digiti 
(in  two  parts) 


Biceps 


Brachio-radialis 

Extensor  Carpi  Radialis  Longior 

Extensor  Carpi  Radialis  Brevior 

Supinator  Radii  Brevis 

.Posterior  Interosseous  Nerve 


Extensor  Ossis  Metacarpi 
Pollicis 


Extensor  Brevis  Pollicis 

Radial  Nerve 

Extensor  Longus  Pollicis 

Extensor  Indicis 


Extensor  Brevis  Pollicis 


Extensor  Indicis 
\ Extensor  Longus  Polli 


Fig.  202.— Deep  Dissection  of  the  Back  of  the  Fokearm 
(The  Radial  Nerve  and  the  Dorsal  Branch  of  the  Ulnar  Nerve  are  also  sliown). 


366  A  MANUAL  OF  ANATOMY 

in  doing  so,  the  nerve  passes  between  the  small  superficial  and  large 
deep  lamina,  of  which  the  muscle  is  composed. 

2.  Extensor  Ossis  Metacarpi  Pollicis — Origin. — (i)  The  posterior 
surface  of  the  shaft  of  the  radius  for  fully  2  inches  below  the  posterior 
oblique  line,  where  it  meets  the  supinator  radii  brevis  ;  (2)  the  ad- 
jacent portion  of  the  interosseous  membrane  ;  and  (3)  the  outer 
part  of  the  posterior  surface  of  the  shaft  of  the  ulna  for  a  short 
distance  below  the  oblique  line,  which  limits  the  insertion  of  the 
anconeus. 

Insertion. — The  outer  side  of  the  base  of  the  metacarpal  bone  of 
the  thumb. 

The  muscle  passes  downwards  and  outwards,  and  its  strong  tendon 
is  closely  accompanied  by  that  of  the  extensor  brevis  pollicis.  Both 
of  these  tendons  cross  those  of  the  radial  extensors  of  the  wrist,  and 
traverse  the  groove  on  the  outer  side  of  the  styloid  process  of  the 
radius,  where  they  occupy  the  outermost  compartment  of  the 
posterior  annular  ligament.  The  tendon  at  its  insertion  gives  a 
slip  to  the  thenar  portion  of  the  palmar  fascia,  which  gives  it  a 
double  appearance. 

Nerve-supply. — ^The  posterior  interosseous  nerve. 

Action. — (i)  To  extend  and  abduct  the  metacarpal  bone  of  the 
thumb,  and  (2)  to  abduct  the  wrist-joint  (external  lateral  flexion). 

3.  Extensor  Brevis  Pollicis  (extensor  primi  intemodii  pollicis) — 
Origin. — The  posterior  surface  of  the  shaft  of  the  radius,  and  the  inter- 
osseous membrane,  for  a  short  distance  below  the  preceding  muscle. 

Insertion. — The  back  of  the  base  of  the  first  phalanx  of  the  thumb. 

The  muscle  closely  accompanies  the  extensor  ossis  metacarpi 
pollicis. 

Nerve-supply. — The  posterior  interosseous  nerve. 

Action. — (i)  To  extend  the  metacarpo-phalangeal  joint  of  the 
thumb,  and  (2)  to  act  as  a  feeble  auxiliary  to  the  extensor  ossis 
metacarpi  pollicis. 

4.  Extensor  Longus  Pollicis  (extensor  secundi  internodii  pollicis) 
— Origin. — (i)  The  outer  part  of  the  posterior  surface  of  the  shaft  of 
the  ulna  over  about  its  middle  third,  commencing  immediately  below 
the  extensor  ossis  metacarpi  pollicis  ;  and  (2)  the  adjacent  portion 
of  the  interosseous  membrane. 

Insertion. — ^The  back  of  the  base  of  the  distal  phalanx  of  the 
thumb. 

The  muscle  is  directed  downwards  and  outwards,  and  its  tendon 
passes  beneath  the  posterior  annular  ligament,  where  it  occupies  the 
narrow  oblique  groove  on  the  radius,  internal  to  the  radial  tubercle. 

Nerve-supply. — The  posterior  interosseous  nerve. 

Action. — ^To  extend  the  distal  phalanx  of  the  thumb.  Thereafter 
the  muscle,  which  acts  strongly,  assists  in  extending  the  first 
phalanx  and  metacarpal  bone,  the  thumb  being  drawn  backwards. 
It  is  also  an  auxiliary  extensor  of  the  wrist- joint. 

5.  Extensor  Indicis — Origin. — (i)  The  outer  part  of  the  posterior 
surface  of  the  shaft  of  the  ulna,  commencing  just  below  the  middle 


THE   UPPER  LIMB 


367 


Extensor  Ossis  Metacarpi  Pollicis 
Extensor  Brevis  Pollicis 


Posterior  Annular  Ligament 

Ext.  Carpi  Radialis  Brevior._ 
Ext.  Carpi  Radialis  Longior 
Extensor  Brevis  Pollicis 

Extensor  Longu 
Pollicis 

ist  Dors.  Interosseous  - 

(Abductor  Indicis) 
Add.  Obliquus,  and 
Add.  Transversus, 

Pollicis  /i . 

(^1 


Extensor  Carpi  Ulnaris 
Extensor  Minimi  Digiti 
Extensor  Indicis 
Extensor  Communis 
Digitorum 


Extensor  Minimi 
Digiti  (in  two  parts) 

Connecting  Band 
Extensor  Indicis 


v-r>^ 


Fig.  203. — The  Muscles  and  Tendons  of  the  Back  of 
THE  Wrist  and  Hand. 


I.,  II.,  III.,  IV.,  Tendons  of  Extensor  Communis  Digitorum. 


368  A   MANUAL  OF  ANATOMY 

third,  and  reaching  to  near  the  lower  end  of  the  bone ;  and  {2)  the 
lower  part  of  the  interosseous  membrane. 

Insertion. — ^The  inner  side  of  the  common  extensor  tendon  of  the 
index  finger,  which  it  joins  at  the  metacarpo-phalangeal  joint. 

The  muscle  is  directed  downwards  and  outwards,  and  its  tendon 
passes  beneath  the  posterior  annular  ligament,  where  it  occupies 
the  innermost  groove  on  the  back  of  the  radius,  in  company  with 
the  common  extensor  tendons,  beneath  which  it  lies. 

Nerve-supply. — The  posterior  interosseous  nerve. 

Action. — (i)  The  muscle  is  the  special  extensor  of  the  index  finger, 
as  in  pointing  ;  and  (2)  it  acts  as  a  feeble  auxiliary  extensor  of  the 
wrist-joint. 

The  muscle  is  covered  by  the  extensor  communis  digitorum, 
extensor  minimi  digiti,  and  extensor  carpi  ulnaris. 

Posterior  Annular  Ligament. — ^This  is  a  thickened  portion  of  the 
deep  fascia  of  the  back  of  the  forearm,  and  it  lies  obliquely  on  the 
back  of  the  wrist.  It  is  attached  externally  to  the  lower  part  of  the 
anterior  border  of  the  radius,  and  internally  to  the  inner  and  back 
part  of  the  cuneiform  and  pisiform  bones,  as  well  as  to  the  hypo- 
thenar  portion  of  the  palmar  fascia.  Its  direction  is  inwards  and 
downwards,  and  it  bridges  over  the  various  grooves  in  this  region, 
sending  deep  processes  to  be  attached  to  the  ridges  which  separate 
them.  In  this  manner  these  grooves  are  converted  into  fibro- 
osseous  canals  for  the  passage  of  the  extensor  tendons.  These 
canals  are  six  in  number,  four  being  on  the  radius,  one  between  that 
bone  and  the  ulna,  and  one  on  the  ulna.  Proceeding  from  without 
inwards,  the  first  canal  corresponds  with  the  groove  on  the  outer 
surface  of  the  styloid  process  of  the  radius,  and  it  contains  the 
tendons  of  the  extensor  ossis  metacarpi  pollicis  and  extensor  brevis 
pollicis.  The  second  canal  corresponds  with  the  outer  broad  groove 
on  the  back  of  the  radius,  and  it  contains  the  tendons  of  the  extensor 
carpi  radialis  longior  and  extensor  carpi  radialis  brevior.  The 
third  canal  corresponds  with  the  narrow,  deep,  oblique  groove  on 
the  back  of  the  radius,  internal  to  the  radial  tubercle  which  overhangs 
it,  and  it  contains  the  tendon  of  the  extensor  longus  pollicis.  The 
fourth  canal  corresponds  with  the  broad,  innermost  groove  on  the 
back  of  the  radius,  and  it  transmits  the  tendons  of  the  extensor 
communis  digitorum  and  extensor  indicis,  together  with  the  pos- 
terior interosseous  nerve  and  posterior  branch  of  the  anterior  inter- 
osseous artery.  The  fifth  canal  corresponds  with  the  groove  between 
the  radius  and  ulna,  and  it  contains  the  tendon  of  the  extensor 
minimi  digiti.  The  sixth  canal  corresponds  with  the  groove  on 
the  back  of  the  ulna,  between  the  styloid  process  and  head  of  the 
bone,  and  it  transmits  the  tendon  of  the  extensor  carpi  ulnaris. 
Each  of  the  foregoing  canals  is  lined  by  a  separate  synovial  sheath, 
and  these  sheaths  extend  for  a  little  above  and  below  the  posterior 
annular  ligament. 

Deep  Fascia  of  the  Back  of  the  Hand. — The  deep  fascia  in  this 
region  is  continuous  above  with  the  posterior  annular  ligament,  and 


THE   UPPER  LIMB 


369 


at  either  side  with  the  thenar  and  hypothenar  portions  of  the  palmar 
fascia.  It  covers  the  extensor  tendons,  with  which  it  is  intimately 
connected.  Besides  this  fascia  there  is  another  fascial  investment, 
which  is  placed  beneath  the  extensor  tendons.  This  deeper  layer 
covers  the  dorsal  interosseous  muscles,  and,  in  the  intervals  between 
them,  it  is  attached  to  the  dorsal  aspects  of  the  shafts  of  the  meta- 
carpal bones. 

Second  Part  of  the  Radial  Artery. — The  second  part  of  the  vessel 
winds  backwards  below  the  styloid  process  of  the  radius  to  the  back 
of  the  wrist.  It  extends  from  a  point  on  the  front  of  the  radius 
about  ^  inch  internal  to  the  styloid  process  to  the  upper  end  of  the 


Posterior  Annular  Ligament_. 

Extensor  Minimi  Digiti 
Extensor  Carpi  Ulnaris  — 


.  -Extensor  Communis 
Digitorum 

Radial  Carpal  Extensors 

_  Extensor  Brevis  Pollicis 

--~  Extensor  Longus  Pollicis 


Fig. 


204. — The  Synovial  Sheaths  of  the  Extensor  Tendons 
(after  L.  Testut's  'Anatomie  Humaine'). 


first  interosseous  space  on  its  posterior  aspect,  where  it  dips  between 
the  two  heads  of  the  abductor  indicis  muscle,  and  ends  in  the  third 
part.     Its  course  is  at  first  backwards  and  then  downwards. 

Relations — Superficial. — The  integument,  radial  vein,  branches  of 
the  radial  nerve,  tendons  of  the  extensor  ossis  metacarpi  pollicis, 
extensor  brevis  pollicis,  and  extensor  longus  pollicis,  the  latter 
crossing  the  vessel  just  before  it  disappears  between  the  two  heads  of 
the  abductor  indicis.  At  first  it  is  deeply  placed,  but  afterwards 
it  is  superficial,  and,  in  the  living  subject,  i)ulsation  may  be  felt 
in  it  in  the  triangular  hollow  below  and  behind  the  radial  styloid 

24 


370 


A  MANUAL  OF  ANATOMY 


process.  Deep. — ^The  external  lateral  ligament  of  the  wrist-joint, 
and  the  scaphoid  and  semilunar  bones.  It  is  accompanied  by  two 
venae  comites. 

Branches. — ^The  branches  are  the  posterior  radial  carpal,  first 
dorsal  interosseous,  two  arteriae  dorsales  pollicis,  and  arteria 
dorsalis  indicis. 

The  posterior  radial  carpal  artery,  of  small  size,  arises  from  the 
radial  as  it  lies  upon  the  external  lateral  ligament.     It  passes  in- 


Ext.  Carpi  Ulnaris 


Posterior  Ulnar.  _ 
Carpal  Artery 

2nd  and  3rd  Dors. 
Inteross.  Arteries '~~ 

'  Superior 
Perforating  Artery 


Extensor  Carpi  Radialis  Brevior 
Extensor  Carpi  Radialis  Longior 

Post.  Branch  of  Ant.  Inteross.  Artery 

-Posterior  Radial  Carpal  Artery 
■ist  Dorsal  Interosseous  Artery 
Radial  Artery  at  Wrist 

Extensor  Brevis  Pollicis 

_  -Arteria  Dorsalis  Pollicis 


Extensor  Longus 
Pollicis 


Fig.   205. 


-The  Arteries  of  the  Back  of  the  Wrist  and  Hand 
(after  L.  Testut's  '  Anatomie  Humaine  '). 


wards  on  the  back  of  the  wrist  beneath  the  extensor  tendons,  and 
anastomoses  with  the  posterior  ulnar  carpal  and  posterior  branch 
of  the  anterior  interosseous  to  form  the  posterior  carpal  arch. 

The  first  dorsal  interosseous  artery  arises  from  the  preceding, 
or  from  the  radial  a  little  lower  down.  It  passes  to  the  upper 
end  of  the  second  interosseous  space,  where  it  receives  a  superior 


THE   UPPER  LIMB 


371 


perforating  branch  from  the  deep  palmar  arch.  It  then  descends 
over  that  space  towards  the  cleft  between  the  index  and  middle 
fingers,  where  it  may  send  forward  an  inferior  perforating  branch 
to  join  the  fourth  or  outermost  digital  artery  from  the  superficial 
palmar  arch.  Thereafter  it  divides  into  two  dorsal  collateral  digital 
arteries  for  the  contiguous  sides  of  the  index  and  middle  fingers. 

The  second  and  third  dorsal  interosseous  arteries  are  branches  of 
the  posterior  carpal  arch.  They  descend  over  the  backs  of  the  third 
and  fourth  interosseous  spaces,  at  the  upper  ends  of  which  each 
receives  a  superior  perforating  branch  from  the  deep  palmar  arch. 
Near  the  clefts  between  the  middle  and  ring,  and  ring  and  little 
fingers,  they  may  send  forwards  inferior  perforating  branches  to  join 
the  second  and  third  digital  arteries  from  the  superficial  palmar 
arch,  and  thereafter  each  divides  into  two  dorsal  collateral  digital 
arteries  for  the  contiguous  sides  of  the  middle  and  ring,  and  ring  and 
little  fingers.  The  dorsal  digital  artery  of  the  inner  side  of  the  little 
finger  arises  from  the  third  (innermost)  dorsal  interosseous,  or  from 
the  posterior  ulnar  carpal. 

The  arterise  dorsales  pollicis,   two  in   number,  arise  separately 
or  by  a  common  trunk,  from  the  radial  opposite  the  base  of  the  first 
metacarpal  bone,  and  are 
distributed  to  the  sides  of 
the  thumb. 

The  arteria  dorsalis 
indicis  arises  below  the 
preceding,  just  before  the 
radial  dips  between  the 
two  heads  of  the  abductor 
indicis.  It  descends  on  the 
outer  side  of  the  second 
metacarpal  bone,  and  sup- 
plies the  outer  side  of  the 
index  finger. 

The  distribution  of  the 
dorsal  digital  arteriesceases, 
as  a  rule,  about  the  level 
of  the  first  interphalangeal 
joint. 

The  Interosseous  Muscles. 

The  interosseous  muscles 
are  seven  in  number,  and 
are  arranged  in  two  groups 
— three  palmar  and  four 
dorsal.  The  palmar  inter- 
ossei  are  seen  only  on  the 
palmar    aspect,    but     the 

dorsal  interossei  are  seen  on         Fig,  206.— Thk  1'almar  Interosseou.s 
both  aspects  of  the  hand.  Muscles  ok  thk  Right  Hand. 

24 — 2 


372 


A   MANUAL  OF  ANATOMY 


The  palmar  interossei  belong"  to  the  index,  ring,  and  Httle 
fingers,  and  they  are  named  from  without  inwards — first,  second, 
and  third.  Each  is  connected  only  with  one  metacarpal  bone. 
The  first  arises  from  the  inner  aspect  of  the  shaft  of  the  second 
metacarpal  bone,  and  the  second  and  third  from  the  outer  aspects 
of  the  shafts  of  the  fourth  and  fifth  metacarpals.  The  first  is 
inserted  partly  into  the  inner  side  of  the  base  of  the  first  phalanx 
of  the  index  finger,  and  partly  into  the  expansion  of  the  extensor 
tendon  on  the  dorsal  aspect  of  that  phalanx.  The  second  and 
third  are  inserted  in  a  similar  manner  in  the  case  of  the  ring  and 
little  fingers,  except  that  each  is  inserted  into  the  outer  side  of  the 
base  of  the  first  phalanx. 

The  palmar  interossei  are  covered  by  a  thin  fascia,  called  the 
interosseous  fascia.  At  either  side  it  joins  the  thenar  and  hypo- 
thenar  portions  of  the  palmar  fascia,  and  interiorly  it  is  connected 
with  the  transverse  metacarpal  and  anterior  metacarpo-phalangeal 

ligaments.  Two  septa  pass 
between  it  and  the  central 
portion  of  the  palmar  fascia. 
The  dorsal  interossei, 
which  are  four  in  number, 
belong  to  the  index,  middle, 
and  ring  fingers,  the  middle 
finger  having  two.  They  are 
named  from  without  inwards — 
first,  second,  third,  and  fourth, 
the  first  being  specially  called 
the  abductor  indicis.  Each 
muscle  arises  by  two  heads 
from  the  contiguous  sides  of 
the  shafts  of  the  metacarpal 
bones  between  which  it  is 
placed,  and  always  more  ex- 
tensively ^from  the  bone  belong- 
ing to  the  finger  upon  which 
the  muscle  acts.  The  fibres 
of  each  muscle  end  upon  a 
tendon  which  is  placed  in  the 
centre,  and  this  tendon  is  in- 
serted partly  into  the  side  of 
the  base  of  the  first  phalanx  of 
a  finger,  and  partly  into  the 
expansion  of  the  extensor 
tendon  on  the  back  of  that 
phalanx.  The  first  or  abductor 
indicis  is  of  large  size.  Its  outer  large  head  arises  from  the 
proximal  half  of  the  inner  margin  of  the  first  metacarpal  bone, 
and  its  inner  small  head  from  the  whole  length  of  the  outer 
aspect   of   the   shaft  of   the   second   metacarpal.      It   is   inserted 


Fig.  207. — The  Dorsal  Interosseous 
Muscles  of  the  Right  Hand. 


THE   UPPER  LIMB 


373 


into  the  outer  side  of  the  base  of  the  first  phalanx  of  the  index 
finger,  and  the  expansion  of  the  extensor  tendon  on  the  back 
of  that  phalanx.  The  second  is  inserted  into  the  outer  side,  and 
the  third  into  the  inner  side,  of  the  base  of  the  first  phalanx  of  the 
middle  finger,  and  both  into  the  expansion  of  the  extensor  tendon 
on  the  back  of  that  phalanx.  The  fourth  is  inserted  into  the  inner 
side  of  the  base  of  the  first  phalanx  of  the  ring-finger,  and  into  the 
expansion  of  the  extensor  tendon  on  the  back  of  that  phalanx. 

Nerve-supply. — All  the  interossei  are  supplied  by  the  deep 
division  of  the  ulnar  nerve. 

Action. — (i)  The  palmar  interossei  are  adductors,  the  fingers 
which  they  adduct  being  the  index,  ring,  and  little.  (2)  The 
dorsal  interossei  are  abductors,  the  fingers  which  they  abduct  being 
the  index,  middle,  and  ring,  the  middle  finger  having  two  abductors, 
inasmuch  as  it  can  be  drawn  to  either  side  of  the  middle  line  which 
passes  through  its  centre. 

In  speaking  of  adduction  and  abduction  reference  is  made  to  an 
imaginary  line  passing  through  the  centre  of  the  middle  finger, 
adduction  being  movement  towards  that  line,  and  abduction  from 
it.  There  is  another  very  important  action  of  all  seven  interossei, 
in  the  performance  of  which  they  are  assisted  by  the  lumbricales. 
This  action  is  as  follows  :  (i)  to  flex  the  metacarpo-phalangeal 
joints,  in  virtue  of  their  insertion  into  the  first  phalanges  of  the 
four  inner  fingers,  and  (2)  to  extend  their  interphalangeal  joints, 
in  virtue  of  their  insertion  into  the  expansions  of  the  extensor 
tendons.  This  action  is  well  illustrated  in  making  the  hair-  or  up- 
stroke in  writing. 

Between  the  two  heads  of  the  abductor  indicis  superiorly  is  an 
interval  for  the  passage  of  the  radial  vessels,  and  between  the  two 
heads  of  each  of  the  other  dorsal  interossei  superiorly  there  is  an 
interval  for  the  passage  of  a  superior  perforating  artery  from  the 
deep  palmar  arch. 

THE  ELBOW-JOINT. 

The  elbow-joint  belongs  to  the  class  diarthrosis,  and  to  the 
subdivision  ginglymus.  The  articular  surfaces  are  the  trochlea 
and  capitellum  of  the  humerus  above,  and  the  great  sigmoid 
cavity  of  the  ulna  and  the  cup-shaped  depression  on  the  head  of 
the  radius  below.  The  trochlea  articulates  with  the  great  sigmoid 
cavity,  and  the  humeral  capitellum  with  the  head  of  the  radius. 
The  joint  is  surrounded  by  a  capsule,  which  is  made  up  of 
four  ligaments — anterior,  j;)osterior,  external  lateral,  and  internal 
lateral. 

The  anterior  ligament  is  broad  and  thin,  the  central  portion 
being  the  strongest.  Its  fibres  are  attached  superiorly  to  the  front 
of  the  humerus  above  the  coronoid  and  radial  fossae,  and  inferiorly  to 
(i)  the  front  of  the  coronoid  })rf)cess  of  the  ulna,  and  (2)  the  orbicular 
ligament  of  the  radius.     Some  of  its  fibres  run  vertically  and  others 


374 


A  MANUAL  OF  ANATOMY 


obliquely,  the  latter  chiefly  passing  downwards  and  outwards  super- 
ficial to  the  former.  The  ligament  is  closely  covered  by  the  brachialis 
anticus  muscle. 

The  posterior  ligament  is  thin  and  membranous.  Superiorly 
it  is  attached  to  the  upper  part  and  sides  of  the  olecranon  fossa  of 
the  humerus,  and  interiorly  to  (i)  the  front  part  of  the  summit  of 
the  olecranon  process  of  the  ulna,  and  (2)  the  orbicular  ligament 
of  the  radius.  The  most  of  its  fibres  are  disposed  vertically,  but  a 
few  pass  transversely  between  the  margins  of  the  olecranon  fossa. 


Orbicular  Ligament 


Tendon  of  Biceps 
(reflected) 


,.  Anterior  Ligament 


..  Internal  Epicondyle 


.  Brachialis  Anticus 
(I'eflected) 


__  Oblique  Ligament 


Fig.  208. — The  Right  Elbow-Joint  (Anterior  View). 

The  ligament  is  related  to  the  tendon  of  insertion  of  the  triceps, 
some  of  the  fibres  of  the  internal  head  being  inserted  into  it,  under 
the  name  of  the  subanconeus. 

The  external  lateral  ligament  is  a  short,  stout,  flat  band, 
which  is  attached  superiorly  to  the  lower  part  of  the  external  epi- 
condyle of  the  humerus,  and  interiorly  to  the  outer  part  of  the 
orbicular  ligament  of  the  radius.  A  few  of  its  posterior  fibres  pass 
over  the  orbicular  ligament,  and  are  attached  to  the  outer  margin 
of  the  ulna.  It  is  intimately  related  to  the  origins  of  the  extensor 
carpi  radialis  brevior  and  supinator  radii  brevis  muscles. 

The  internal  lateral  ligament  is  triangular,  with  the  apex  up- 


THE  UPPER  LIMB 


375 


wards.  It  is  attached  superiorly  to  the  anterior,  inferior,  and 
posterior  parts  of  the  internal  epicondyle  of  the  humerus,  and 
inferiorly  to  the  inner  margin  of 
the  great  sigmoid  cavity  of  the 
ulna.  It  is  divisible  into  three 
portions — anterior,  posterior,  and 
middle.  The  anterior  portion  is 
attached  superiorly  to  the  front 
and  lower  part  of  the  internal 
epicondyle,  and  inferiorly  to  the 
inner  margin  of  the  coronoid 
process.  The  posterior  portion  is 
attached  superiorly  to  the  lower 
and  back  part  of  the  internal 
epicondyle,  and  inferiorly  to  the 
inner  margin  of  the  olecranon 
process.  The  middle  portion  con- 
sists of  fibres  which  pass  trans- 
versely from  the  olecranon  to  the 
coronoid  process,  and  blend  with 
the  fibrous  band  bridging  over  the  Fig.  209.— The  Posterior  Liga- 
notch  on  the  inner  margin  of  ^ent  of  the  Elbow-Joint. 
the  great  sigmoid  cavity  between 

these   two  processes.     The  ligament  is  intimately  related  to  the 
origin  of  the  flexor  sublimis  digitorum. 
The  synovial  membrane  lines  the  internal  surface  of  the  capsule, 


External  Lateral  Ligament 

Oilncular  Ligament 


Posterior  Ligament  Posterior  Fibres  of  External  Lateral  lyigamcnt 

Fig.  210. — The  Right  Elbow-Joint  (External  View). 


and  inferiorly  is  continued  into  the  superior  radio-ulnar  joint, 
where  it  lines  the  internal  surface  of  the  orbicular  ligament  and 
upper  part  of  the  neck  of  the  radius.     It  also  lines  the  coronoid. 


376 


A  MANUAL  OF  ANATOMY 


radial,  and  olecranon  fossse  of  the  humerus,  which  contain  small 
cushions  of  fat. 

Muscular  Relations. — The  capsule  is  closely  related  to  the  fol- 
lowing muscles  :  anteriorly,  the  brachialis  anticus ;  posteriorly,  the 
triceps  ;  externally,  the  extensor  carpi  radialis  brevior  and  supinator 
radii  brevis  ;  and  internally,  the  flexor  sublimis  digitorum. 


Orbicular 
Ligament 


Tendon  of  Bicep 


Oblique  Ligament 


Internal  Lateral 

Ligament 
(Anterior  portion) 


Internal  Lateral  Ligament 
(Posterior  portion) 


Internal  Lateral  Ligament 
(Middle  portion) 

Fig.  211. — The  Right  Elbow-Joint  (Internal  View). 


Arterial  Supply. — ^The  superior  and  inferior  profundae,  anasto- 
motica  magna,  anterior  and  posterior  ulnar  recurrent,  radial 
recurrent,  and  posterior  interosseous  recurrent,  arteries. 

Nerve-supply. — ^The  musculo-spiral,  musculo-cutaneous,  median, 
and  ulnar  nerves. 

Movements. — Two  movements  are  allowed,  namely,  flexion  and  extension, 
these  being  limited  by  the  tension  of  the  structures  related  to  the  joint,  and 
flexion  also  by  the  coming  into  contact  of  the  fleshy  parts  of  the  forearm  and 
arm. 

Muscles  concerned  in  the  Movements — Flexion. — This  is  produced  by  the 
biceps,  brachialis  anticus,  brachio-radiaiis,  and,  as  auxiliaries,  the  muscles 
arising  from  the  internal  epicondyle  of  the  humerus.  Extension. — This  is 
produced  by  the  triceps  and  anconeus,  and,  as  auxiliaries,  the  muscles  arising 
from  the  external  epicondyle. 


THE   UPPER  LIMB 


377 


THE  RADIO-CARPAL  OR  WRIST-JOINT. 

The  wrist-joint  belongs  to  the  class  diarthrosis,  and  to  the  sub- 
division condylarthrosis.  The  articular  surfaces  are  the  carpal 
surface  of  the  radius  and  the  triangular  fibro-cartilage  above,  and 
the  superior  facets  of  the  scaphoid,  semilunar,  and  cuneiform,  as 
well  as  the  interosseous  ligaments  on  either  side  of  the  semilunar, 
below.  The  carpal  surface  of  the  radius,  which  presents  an  outer 
or  scaphoid  and  an  inner  or  semilunar  division,  and  the  triangular 
fibro-cartilage  form  a  socket,  which  is  concave  from  side  to  side 


Anterior  Ligament -- 

External  Lateral  Ligament  — 
Ligaments  of  ist  Row  — 


Interosseous  Membrane 
Ulna 

Anterior  Radio-ulnar 
Ligament 

Internal  Lateral  Ligament 
Flexor  Carpi  Ulnaris 


External  Lateral  Ligaments 
of  ist  and  2nd  Rows 

Ligaments  of  2nd  Row 


Capsule  of  Carpo- 
metacarpal Joint 
of  Thumb 


"Pisiform  Bone 
~~— Ligaments  of  ist  &  2nd  Rows 

Pisi-uncinate  Ligament 

Pisi-metacarpal  Ligament 

■Hook  of  Unciform 


Intermetacarpal  Ligaments 


2.M 


5.M.     4.M 


Fig.   212. — The  Ligaments   of  the   Radio-carpal,  Carpal,  Carpo- 
metacarpal,  AND  Intermetacarpal  Joints  (Anterior  View). 


and  from  before  backwards.  The  superior  facets  of  the  carpal 
bones  extend  more  upon  the  dorsal  than  palmar  aspects,  and  they 
present  a  convexity.  The  ulna  is  entirely  excluded  from  this 
joint  by  the  triangular  fibro-cartilage.  The  joint  is  surrounded  by 
a  capsule,  which  is  made  up  of  four  ligaments,  namely,  anterior, 
])Osterior,  external,  and  internal. 

The  anterior  ligament  is  a  broad,  strong  membrane,  the  fibres 
of  which  are  attached  j)osteriorly  to  the  front  of  the  lower  end  of  the 
radius,  close  above  the  anterior  border,  and  to  the  anterior  margin 
of  the  triangular  fibro-cartilage.  Inferiorly  they  are  attached  to 
the  j)almar  surfaces  of  the  scaphoid,  semilunar,  and  cuneiform  bones.. 
The  fibres  for  the  most  part  are  directed  downwards  and  inwards. 


37S  A   MANUAL  OF  ANATOMY 

The  posterior  ligament  is  a  broad,  weak  membrane,  the  fibres 
of  which  are  attached  superiorly  to  the  posterior  border  of  the 
radius  and  triangular  fibro-cartilage,  and  inferiorly  to  the  dorsal 
surfaces  of  the  scaphoid,  semilunar,  and  cuneiform  bones,  especially 
the  latter.     Its  fibres  are  directed  do\^Tiwards  and  inwards. 

The  external  lateral  ligament  is  a  strong,  flattened  band,  which 
extends  from  the  tip  of  the  styloid  process  of  the  radius  to  the  outer 
aspects  of  the  scaphoid  and  trapezium.  It  supports  a  portion  of  the 
second  part  of  the  radial  artery. 

The  Internal  lateral  ligament  is  a  strong,  round  cord,  which 
extends  from  the  tip  of  the  stjdoid  process  of  the  ulna  to  the  cunei- 
form and  pisiform' bones. 

The  synovial  membrane  lines  the  internal  surface  of  the  capsule 
and  the  upper  surfaces  of  the  interosseous  ligaments  on  either  side 
of  the  semilunar.  In  cases  where  the  triangular  fibro-cartilage  is 
perforated  it  is  continuous  with  the  S3Tiovial  membrane  of  the  in- 
ferior radio-ulnar  joint,  but  it  is  distinct  from  that  of  the  carpal 
articulations. 

Muscular  Relations — Anterior. — From  within  outwards,  the  flexor 
carpi  ulnaris,  flexor  profundus  digitonmi,  flexor  longus  pollicis,  and 
flexor  carpi  radialis.  Posterior. — From  within  outwards,  the 
extensor  carpi  ulnaris,  extensor  minimi  digiti,  extensor  communis 
digitorum  with  the  extensor  indicis,  extensor  longus  pollicis,  ex- 
tensor carpi  radiahs  brevior,  and  extensor  carpi  radialis  longior. 
External. — The  extensor  ossis  metacarpi  pollicis  and  extensor  brevis 
poUicis. 

Arterial  Supply. — The  anterior  and  posterior  carpal  retia. 

Nerve-supply. — ^The  median,  ulnar,  and  posterior  interosseous, 
ner\'es. 

Movements. — Six  movements  are  allowed,  namely,  palmar  flexion,  dorsal 
flexion,  ulnar  flexion  or  adduction,  radial  flexion  or  abduction,  extension,  and 
circumduction.  In  all  forms  of  flexion  an  angle  is  produced  between  the 
hand  and  forearm.  Extension  is  straightening,  so  as  to  efface  the  angle 
produced  b^-  flexion.  Circumduction  is  a  combination  of  all  the  foregoing 
movements  occurring  in  alternate  succession.  Adduction  is  more  extensive 
than  abduction,  the  st\doid  process  of  the  radius  limiting  the  latter  move- 
ment. "^ATien  the  hand  is  in  hne  with  the  forearm,  the  scaphoid  di%'ision 
of  the  carpal  articular  surface  of  the  radius  articulates  with  the  scaphoid  bone, 
and  the  semilunar  division  of  the  carpal  articular  surface  of  the  radius,  together 
with  the  triangular  fibro-cartilage,  articulates  with  the  semilunar  bone,  the 
faceted  part  of  the  upper  surface  of  the  cuneiform  being  in  contact  vdih  the 
inner  portion  of  the  capsule.  When,  however,  the  hand  is  adducted — that  is 
to  saA",  flexed  in  an  inward  direction — the  faceted  part  of  the  upper  surface 
of  the  cuneiform  articulates  %'iith  the  triangular  fibro-cartilage,  the  semilunar 
bone  partially  articulates  -I'i-ith  the  scaphoid  surface  of  the  radius,  and  the 
scaphoid  bone  partially  articulates  with  the  outer  portion  of  the  capsule. 


THE   UPPER  LIMB 


379 


THE  RADIO-ULNAR  JOINTS. 

The  radius  and  ulna  are  united  by  a  superior  and  an  inferior 
radio-ulnar  joint,  and  there  is  an  intermediate  connection  between 
their  shafts. 

Superior  Radio-ulnar  Joint. — This  joint  belongs  to  the  class 
diarthrosis,  and  to  the  subdivision  trochoides.  The  articular  sur- 
faces are  the  deep  inner  part  of  the  head  of  the  radius,  and 
the  small  sigmoid  cavity  of  the  ulna.  There  is  one  ligament  at 
this  joint,  namely,  the  orbicular  or  annular  ligament.  This  is  a 
strong  fibrous  band,  which  forms  about 
four-fifths  of  a  circle,  and  surrounds 
the  circumference  of  the  head  of  the 
radius,  which  it  retains  in  contact 
with  the  small  sigmoid  cavity.  Its 
extremities  are  attached  to  the 
anterior  and  posterior  margins  of  the 
small  sigmoid  cavity.  The  ligament 
is  smaller  below  than  above,  and  so 
it  maintains  the  head  of  the  radius  in 
position.  Its  lower  border  is  attached 
to  the  neck  of  the  radius  by  loosely- 
disposed  fibres.  It  gives  attachment 
to  (i)  the  external  lateral  ligament 
of  the  elbow-joint  externally,  (2)  the 
outer  fibres  of  the  anterior  ligament 
anteriorly,  and  (3)  a  portion  of  the 
posterior  ligament  posteriorly. 

The  synovial  membrane  is  con- 
tinuous with  that  of  the  elbow-joint, 
and  lines  the  inner  surface  of  the 
orbicular  ligament  and  upper  part  of 
the  neck  of  the  radius. 

Muscular  Relations. — Extensor  carpi 
radialis  brevior  and  supinator  radii 
brevis. 

Arterial  Supply. — The  radial  recurrent  and  posterior  interosseous 
recurrent  arteries. 

Nerve-supply. — The  musculo-cutaneous  and  musculo  -  spiral 
ncrv(,'s. 

Inferior  Radio-ulnar  Joint. — This  joint  belongs  to  the  class 
diarthrosis,  and  to  the  subdivisi<jn  trochoides.  The  articular  sur- 
faces are  the  sigmoid  cavity  of  the  radius,  and  the  outer  side  of 
the  head  of  the  ulna.  The  ligaments  are  anterior  and  posterior, 
and  the  triangular  fibro-rartilagc 

The  anterior  and  posterior  radio-ulnar  ligaments  consist  of  scat- 
tered fibres  in  front  of  and  behind  the  joint,  which  are  attached  to 
the  adjacent  portions  of  the  radius  and  ulna.     The  bones,  however, 


Fig.  213. — The  Upper  I£nd 
OF  THE  Ulna,  .a.nd  the 
Orbicul.\r  Ligament. 


3So  A   MANUAL  OF  ANATOMY 

are  chiefly  connected  by  the  triangular  flbro-cartilage,  which  is  a 
strong  plate.  It  is  attached  by  its  base  to  the  ridge  on  the  radius 
which  separates  the  sigmoid  cavity  from  the  carpal  articular  surface, 
and  by  its  apex  to  the  pit  on  the  lower  end  of  the  ulna  at  the  root 
of  the  styloid  process.  It  is  thicker  at  the  circumference  than  at  the 
centre,  and  its  anterior  and  posterior  borders  are  connected  with  the 
anterior  and  posterior  ligaments  of  the  wrist-joint.  Its  upper 
surface  is  related  to  the  lower  end  of  the  ulna,  and  its  lower  surface 
enters  into  the  wrist- joint,  articulating  with  the  semilunar  bone 
when  the  hand  is  in  line  with  the  forearm,  and  with  the  faceted 
part  of  the  upper  surface  of  the  cuneiform  bone  when  the  hand  is 
adducted.     It  sometimes  presents  a  perforation. 

The  synovial  membrane  is  very  loose,  and  is  known  as  the  mem- 
hrana  sacciformis.  It  consists  of  two  parts,  vertical  and  hori- 
zontal, which  are  continuous  with  each  other.  The  vertical  part 
extends  upwards  between  the  head  of  the  ulna  and  the  sigmoid  cavity 
of  the  radius,  and  the  horizonta.1  part  lies  between  the  lower  end  of 
the  ulna  and  the  upper  surface  of  the  triangular  flbro-cartilage. 
When  the  flbro-cartilage  is  perforated  the  membrana  sacciforrrils 
is  continuous  with  the  radio-carpal  synovial  membrane. 

Arterial  Supply. — The  anterior  and  posterior  ulnar  carpal  arteries. 

Nerve-supply. — The  anterior  and  posterior  interosseous  nerves. 

Intermediate  Connection  between  the  Radius  and  Ulna. — This  is 
a  variety  of  syndesmosis.  The  shafts  of  the  two  bones  are  connected 
by  two  ligaments,  namely,  the  interosseous  membrane  and  the 
oblique  ligament. 

The  interosseous  membrane  is  a  strong  expansion  which  ex- 
tends between  the  interosseous  borders  of  the  shafts  of  the  radius 
and  ulna.  Its  fibres  pass  principally  downwards  and  outwards 
from  the  radius  to  the  ulna,  but  some  pass  in  the  opposite  direction. 
Superiorly  it  reaches  to  a  point  about  i  inch  below  the  bicipital 
tuberosity  of  the  radius,  and  inferiorly  to  the  upper  part  of  the 
sigmoid  cavity  of  that  bone.  The  posterior  interosseous  artery 
passes  backwards  between  the  two  bones  over  its  upper  border,  and 
the  posterior  branch  of  the  anterior  interosseous  artery  pierces  it  a 
little  above  its  lower  end.  The  membrane,  besides  connecting  the 
shafts  of  the  two  bones,  serves  to  give  origin  to  muscles  of  the  front 
and  back  of  the  forearm. 

Relations — Anterior. — The  flexor  profundus  digitorum  and  flexor 
longus  pollicis,  with  the  anterior  interosseous  vessels  and  nerve 
lying  between  the  two,  as  low  as  the  lower  fourth,  where  the  pronator 
quadratus  forms  the  anterior  relation.  Posterior. — From  above  down- 
wards, the  supinator  radii  brevis,  extensor  ossis  metacarpi  pollicis, 
extensor  brevis  pollicis,  extensor  longus  pollicis,  extensor  indicis, 
and,  for  a  short  distance  below,  the  posterior  interosseous  nerve  and 
posterior  branch  of  the  anterior  interosseous  artery. 

The  oblique  ligament  is  a  narrow  band  which  extends  from  the 
tuberosity  of  the  ulna  to  the  radius,  close  below  the  lower  and  back 
part  of  the  bicipital  tuberosity.     Its  flbres  are  directed  downwards 


THE   UPPER  LIMB  381 

and  outwards.  The  interval  between  it  and  the  upper  border  of 
the  interosseous  membrane  gives  passage  to  the  posterior  inter- 
osseous vessels. 

Movements. — The  movements   allowed  are  pronation  and  supination,   the 

latter  being  the  stronger.  In  pronation  the  lower  part  of  the  radius,  carrying 
with  it  the  hand,  crosses  over  the  lower  part  of  the  ulna  so  as  to  lie  on  its  inner 
side,  the  dorsum  of  the  hand  being  directed  upwards.  In  supination  the 
radius  and  hand  retrace  their  steps,  so  that  the  lower  part  of  the  radius  lies 
on  the  outer  side  of  the  ulna,  the  palm  of  the  hand  being  directed  upwards. 
At  the  superior  radio-ulnar  joint  the  head  of  the  radius  rotates  upon  the  capi- 
tellum  of  the  humerus  within  the  orbicular  ligament,  and  comes  into  closest 
relation  with  the  capitellum  in  semiflexion  of  the  elbow-joint  and  semi- 
pronation  of  the  forearm.  At  the  inferior  radio-ulnar  joint  the  radius, 
carrying  with  it  the  triangular  fibro-cartilage,  rotates  upon  the  head  of  the 
ulna,  the  movement  being  one  of  limited  circumduction  around  an  axis  passing 
from  the  centre  of  the  head  of  the  radius  to  the  styloid  process  of  the  ulna. 
There  is  also  a  limited  amount  of  circumduction  on  the  part  of  the  ulna,  the 
lower  end  of  that  bone  moving  outwards  and  backwards  in  pronation,  and 
inwards  and  forwards  in  supination. 

Muscles  concerned  in  the  Movements — (i )  Pronation. — The  principal  pronator 
muscles  are  the  pronator  radii  teres  and  pronator  quadratus.  (2)  Supination. 
^The  principal  supinator  muscles  are  the  biceps  and  supinator  radii  brevis. 
The  brachio-radialis  is  also  a  feeble  supinator,  but  it  only  acts  as  such  to 
the  extent  of  semisupination.  The  biceps  is  enabled  to  act  as  a  supinator  in 
virtue  of  its  insertion  into  the  back  part  of  the  bicipital  tuberosity  of  the  radius. 


THE  ARTICULATIONS  OF  THE  HAND. 

Carpal  Joints. — The  carpal  joints  are  divided  into  those  of  the 
first  row,  those  of  the  second  row,  and  the  transverse  carpal 
joint. 

Joints  of  the  First  Row. — These  belong  to  the  class  diarthrosis, 
and  to  the  subdivision  arthrodia.  The  bones  of  the  first  row,  with 
the  exception  of  the  pisiform,  are  united  by  two  dorsal,  two  palmar, 
and  two  interosseous  ligaments.  The  dorsal  and  palmar  ligaments 
extend  transversely  from  the  front  and  back  of  the  semilunar  to  the 
corresponding  surfaces  of  the  scaphoid  and  cuneiform.  The  two 
interosseous  ligaments  are  placed  one  on  either  side  of  the  semilunar, 
and  they  connect  it  with  the  scaphoid  and  cuneiform.  They  are 
situated  high  up  on  the  lateral  surfaces  of  the  bones,  and  their 
upper  surfaces  form  part  of  the  lower  wall  of  the  radio-carpal  joint. 

The  synovial  membrane  is  continuous  with  that  of  the  transverse 
carpal  joint. 

Pisiform  Joint. — The  pisiform  bone  is  united  to  the  front  of  the 
cuneiform  by  a  cajjsular  ligament,  which  surroimds  the  joint  and  is 
attached  to  the  bones  at  the  circumference  of  their  opposed  articular 
surfaces.  Superiorly  the  caj^sule  is  connected  with  the  tendon  of 
insertion  of  the  flexor  carpi  ulnaris,  and  inferiorly  with  two  jn'olonga- 
tions  of  that  tendon,  called  the  fisi-uncinate  and  pisi-tnetacar[)al 
ligaments.  The  former  is  attached  to  the  hook  of  the  unciform  bone, 
and  the  latter  to  the  base  of  the  fifth  metacarpal.     These  ligaments 


382 


A  MANUAL  OF  ANATOMY 


act  by  keeping  the  pisiform  bone  fixed  during  the  action  of  the  flexor 
carpi  ulnaris. 

The  pisiform  joint  has  a  special  synovial  membrane. 

Joints  of  the  Second  Row.  —  These  belong  to  the  class  diar- 
throsis,  and  to  the  subdivision  arthrodia.  The  four  bones  of  the 
second  row  are  connected  by  three  dorsal,  three  palmar,  and  three 
interosseous  ligaments,  which  are  disposed  similarly  to  those  of  the 
first  row. 

The  synovial  membrane  is  continuous  with  that  of  the  transverse 
carpal  joint. 

Transverse  Carpal  Joint. — This  is  the  joint  between  the  first 
and  second  rows.     It  belongs  to  the  class  diarthrosis,  and  partly  to 


Interosseous  Membrane. ; 

Ulna 


Posterior  Radio-ulnar 

Ligament 

Internal  Lateral  Ligament 


Ligaments  between  ist. 
and  2nd  Rows 

Ligaments  of  2nd  Row^.-^-:^^ 


Intermetacarpal  Ligament — I 


-Styloid  Process  of 

Radius 
» Posterior  Ligament 

-Ext.  Lateral  Ligament 

-Ligaments  of  ist  Row 

_Ext.  Lateral  Ligament 
of  ist  and  2nd  Rows 

.  Carpo-metacarpal 

Ligaments 
Capsule  of  Carpo- 
metacarpal Joint 
of  Thumb 


5.M 


4.M.       3.M.        2.M 


Fig.  214. — Ligaments  of  the  Radio-carpal,  Carpal,  Carpo-metacarpal, 
AND  Intermetacarpal  Joints  (Posterior  View). 


the  subdivision  arthrodia  and  partly  to  the  subdivision  condyl- 
arthrosis.  The  opposed  surfaces  of  the  two  rows  are  each  concavo- 
convex,  the  first  in  a  direction  from  within  outwards,  and  the  second 
from  without  inwards.  The  convexity  of  the  first  row  is  formed  by 
part  of  the  scaphoid,  and  the  concavity  by  part  of  the  scaphoid, 
semilunar,  and  cuneiform.  The  concavity  of  the  second  row  is 
formed  by  the  trapezium  and  trapezoid,  and  the  convexity  by  the 
head  of  the  os  magnum  and  part  of  the  unciform.  The  two  rows 
are  connected  by  dorsal,  palmar,  and  lateral  ligaments.  The  dorsal 
ligaments  are  very  indefinite  and  pass  in  different  directions.  The 
palmar  ligaments  for  the  most  part  radiate  from  the  os  magnum, 


THE  UPPER  LIMB  383 

though  a  few  pass  from  the  other  bones  of  the  second  row.  The 
external  lateral  ligament  connects  the  scaphoid  with  the  trapezium, 
and  the  internal  lateral  connects  the  cuneiform  with  the  unciform. 

Carpal  Synovial  Membrane. — This  membrane  lines  the  transverse 
carpal  joint,  and  gives  off  vertically- disposed  processes.  Two  of 
these  pass  upwards,  one  on  either  side  of  the  semilunar  as  far  as  its 
interosseous  ligaments.  Three  pass  downwards — one  between  the 
trapezium  and  trapezoid,  another  between  the  trapezoid  and  os 
magnum,  and  a  third  between  the  os  magnum  and  unciform.  There- 
after the  synovial  membrane  is  continued  into  the  inner  four  carpo- 
metacarpal joints,  and  this  latter  portion  of  it  sends  processes  into 
the  joints  between  the  bases  of  the  inner  four  metacarpal  bones. 

Arterial  Supply. — The  anterior  and  posterior  carpal  retia. 

Nerve-supply.— The  median,  ulnar,  and  posterior  interosseous 
nerves. 

Movements. — The  movements  between  the  bones  of  each  row  are  extremely 
limited,  and  are  of  a  gliding  nature.  The  movements  at  the  transverse 
carpal  joint  are  more  free,  and  take  the  form  of  flexion  and  extension  in  associa- 
tion ^^'ith  the  corresponding  movements  at  the  radio-carpal  joint.  The 
number  of  the  carpal  articulations  imparts  to  this  part  of  the  hand  consider- 
able strength  and  elasticity,  and  so  enables  it  to  disperse  shock. 

Carpo-metacarpal  Joints. — Inner  Four  Joints. — These  belong  to 
class  diarthrosis,  and  to  the  subdivision  arthrodia.  The  bones  con- 
cerned are  the  trapezium,  trapezoid,  os  magnum,  and  unciform 
above,  and  the  bases  of  the  inner  four  metacarpal  bones  below. 
The  ligaments  are  dorsal,  palmar,  and  interosseous.  The  second, 
third,  and  fourth  metacarpal  bones  receive  each  two  dorsal  liga- 
ments as  a  rule,  and  the  fifth  receives  one,  namely,  from  the  unci- 
form. The  palmar  ligaments  are  usually  one  to  each  bone.  There 
is  only  one  interosseous  ligament,  which  connects  the  adjacent 
parts  of  the  os  magnum  and  unciform  with  the  inner  aspect  of  the 
base  of  the  third  metacarpal  bone  towards  its  palmar  aspect. 

The  synovial  membrane  is  a  continuation  of  that  of  the  carpus. 

These  joints  derive  their  arterial  supply  from  the  radial  and  ulnar 
arteries,  and  their  nerve-supply  from  the  deep  division  of  the  ulnar, 
and  posterior  interosseous,  nerves. 

Movements. — The  movements  are  those  of  flexion  and  extension,  the  former 
being  most  free  in  the  case  of  the  fifth  metacarpal,  as  in  the  formation  of  the 
'  palmar  cup.' 

Carpo-metacarpal  Joint  of  the  Thumb. — This  belongs  to  the 
class  diarthrosis,  and  to  that  variety  of  the  subdivision  arthrodia 
which  is  called  the  reciprocal  or  saddle-joint.  The  bones  which 
enter  into  this  important  joint  are  the  trapezium  and  the  base  of 
the  first  metacarpal.  The  articular  surfaces  are  saddle-shaped, 
and  are  connected  by  a  capsular  ligament,  which  is  attached  round 
the  margin  of  each  articular  surface,  being  strongest  on  the  dorsal 
and  outer  aspects.  This  ligament  is  sufficiently  loose  to  allow  of 
considerable  movement. 


384  A   MANUAL  OF  ANATOMY 

The  synovial  membrane  is  peculiar  to  the  joint. 

Arterial  Supply. — The  arteria  princeps  poUicis  of  the  radial. 

Nerve-supply. — ^The  median  nerve. 

Movements. — The  movements  allowed  are  flexion,  extension,  abduction, 
adduction,  and  circumduction.  It  is  at  this  joint  where  the  important  move- 
ment of  opposition  takes  place,  whereby  the  tip  of  the  thumb  can  be  opposed 
in  succession  to  the  tip  of  each  of  the  four  inner  fingers. 

Intermetacarpal  Joints. — The  basal  intermetacarpal  joints  belong 
to  the  class  diarthrosis,  and  to  the  subdivision  arthrodia.  The 
bones  concerned  are  the  inner  four  metacarpals,  the  first  metacarpal 
bone  standing  off  from  the  second,  with  which  it  has  no  articula- 
tion. The  ligaments  are  dorsal,  palmar,  and  interosseous.  The 
dorsal  ligaments  are  composed  of  stout  fibres,  which  pass  trans- 
versely between  the  contiguous  aspects  of  the  bases.  The  palmar 
ligaments  are  similarly  disposed  in  front.  The  interosseous  liga- 
ments are  strong  bundles  which  2:)ass  between  the  opposed  surfaces 
of  the  bases  to  which  they  are  attached  on  the  distal  sides  of  the 
articular  facets. 

Nerve-supply. — The  deep  division  of  the  ulnar  nerve. 

Arterial  Supply. — The  palmar  and  dorsal  interosseous  arteries. 

The  synovial  membrane  is  a  downward  prolongation  from  that 
of  the  carpus. 

The  heads  of  the  inner  four  metacarpal  bones  are  connected  by 
the  transverse  metacarpal  (deep  transverse)  ligament.  It  extends 
transversely  across  the  palmar  aspects  of  the  heads,  and  its  fibres 
are  attached  to  the  fibrous  plates  on  the  palmar  surfaces  of  the 
metacarpo-phalangeal  joints.  It  receives  the  deep  expansions  of 
the  digital  processes  of  the  central  division  of  the  palmar  fascia, 
and  the  digital  arteries  and  nerves  pass  in  front  of  it,  and  the  in- 
terosseous muscles  behind  it.  It  is  to  be  noted  that  the  transverse 
metacarpal  ligament  excludes  the  head  of  the  first  metacarpal  bone, 
whereas  the  corresponding  ligament  of  the  foot  includes  the  head 
of  the  first  metatarsal. 

The  synovial  membranes  from  the  inferior  radio-ulnar  joint  down 
to  the  intermetacarpal  joints  are  five  in  number,  as  follows  : 

1.  Inferior  radio-ulnar  or  membrana  sacciformis. 

2.  Radio- carpal. 

3.  Pisiform. 

4.  Carpal,  composed  of  carpal  proper,  carpo-metacarpal,  and 
intermetacarpal  portions,  all  continuous  with  one  another. 

5.  Carpo-metacarpal  of  the  thumb. 

Metacarpo-phalangeal  Joints. — These,  belong  to  the  class  diar- 
throsis, and  to  the  subdivision  condylarthrosis,  which  is  a  modifi- 
cation of  enarthrosis  or  ball-and-socket  joint.  In  each  joint  the 
round  head  of  a  metacarpal  bone  articulates  with  the  cup-shaped 
depression  on  the  proximal  end  of  a  first  phalanx. 

Inner  Four  Metacarpo-phalangeal  Joints. — Each  of  these  joints 
has    three   ligaments  —  two   lateral,   and   a   palmar.     The    lateral 


THE  UPPER  LIMB  385 

me tacarpo- phalangeal  ligaments  are  strong  bands  which  are  attached 
above  to  the  dorsal  tubercle  and  palmar  depression  on  either  side 
of  the  head  of  a  metacarpal  bone,  and  below  to  each  side  of  the 
base  of  a  first  phalanx,  and  also  to  the  lateral  margin  of  the  palmar 
fibrous  plate.  Each  is  connected  with  a  deep  expansion  of  a 
digital  process  of  the  central  division  of  the  palmar  fascia.  The 
palmar  ligament  takes  the  form  of  a  fibrous  plate.  It  is  closely 
attached  at  either  side  to  the  lateral  ligaments,  inferiorly  to  the 
palmar  aspect  of  the  base  of  the  first  phalanx,  and  superiorly, 
where  it  is  connected  with  the  transverse  metacarpal  ligament,  it 
is  slightly  attached  to  the  palmar  aspect  of  the  head  of  a  metacarpal 
bone,  close  above  the  articular  cartilage.  It  increases  the  extent 
of  the  phalangeal  socket  for  the  head  of  a  metacarpal  bone,  and  it 
forms  part  of  the  tunnel  for  the  passage  of  a  pair  of  flexor  tendons. 
Its  deep  surface  is  lined  by  the  synovial  membrane  of  the  joint.  There 
is  no  dorsal  ligament,  its  place  being  taken  by  the  extensor  tendon. 

Each  joint  is  provided  with  a  synovial  membrane,  which  is  looser 
in  front  than  behind. 

Arterial  Supply. — The  digital  arteries  from  the  superficial  palmar 
arch,  or  the  palmar  interosseous  from  the  deep  palmar  arch. 

Nerve-supply. — The  deep  division  of  the  ulnar  nerve. 

Movements. — The  movements  are  flexion,  extension,  abduction,  adduction, 
and  circumduction.  Flexion  is  particularly  free,  and  is  combined  with 
adduction.  Extension  is  associated  with  abduction,  and  dorsal  flexion  is 
prevented  by  the  palmar  fibrous  plates  and  flexor  tendons. 

Metacarpo-phalaiigeal  Joint  of  the  Thumb. — ^The  lateral  liga- 
ments of  this  joint  are  similar  to  those  of  the  other  joints,  but  there 
is  no  palmar  fibrous  plate,  its  place  being  taken  by  two  sesamoid 
bones.  Each  of  these  bones  resembles  a  split  pea.  The  palmar 
surface  is  convex,  whilst  the  deep  surface  is  almost  flat  and  covered 
by  cartilage,  to  play  upon  a  groove  on  the  palmar  surface  of  the 
head  of  the  first  metacarpal  bone.  The  two  bones  are  united  by 
fibres  which  pass  between  their  contiguous  surfaces,  and  are  related 
superficially  to  the  tendon  of  the  flexor  longus  pollicis.  Inferiorly 
they  are  connected  by  fibres  with  the  palmar  aspect  of  the  base  of 
the  first  phalanx.  At  either  side  they  are  connected  with  the  lateral 
ligaments,  and  posteriorly  they  are  slightly  connected  with  the  head 
of  the  first  metacarpal  above  the  articular  cartilage.  The  outer 
sesamoid  bone  is  closely  associated  with  the  superficial  head  of  the 
flexor  brevis  })ollicis,  and  the  inner  with  the  adductor  ol)liquus 
pollicis.  The  place  of  a  dorsal  ligament  is  taken  by  the  tendons 
of  the  extensor  brevis,  and  extensor  longus,  pollicis. 

Arterial  Supply. — The  arteria  princeps  pollicis  of  the  radial. 

Nerve-supply. — The  median  nerve. 

Movements. — Flexion,  extension,  and  lateral  moviiiKnl,  the  latter  only 
wlii-ii  thr  joint  is  partially  llexcd. 

Interphalangeal  Joints.  —  These  belong  to  the  class  diarthrosis, 
and  to  the  subdivision  ginglymus.     The  ligaments  are  similar  to 

25 


386  A  MANUAL  OF  ANATOMY 

those  of  the  inner  four  metacarpo- phalangeal  joints,  namely,  two 
lateral,  and  an  anterior  fibrous  plate,  the  extensor  tendon  taking  the 
place  of  a  dorsal  ligament.  Each  joint  is  provided  with  a  synovial 
membrane,  and  the  arterial  and  nerve  supply  are  derived  from  the 
digital  arteries  and  nerves.  Each  of  the  inner  four  fingers  has  two 
interphalangeal  joints,  but  the  thumb,  being  destitute  of  a  middle 
phalanx,  has  only  one,  and  its  dorsal  ligament  is  represented  by 
the  tendon  of  the  extensor  longus  pollicis,  whilst  its  fibrous  plate 
is  grooved  by  the  tendon  of  the  flexor  longus  pollicis. 

Movements. — The  only  movements  allowed  are  flexion  and  extension,  the 
former  being  very  free. 

Joints  with  Interarticular  Fibro-cartilages. — ^The  joints  of  the 
upper  limb  which  have  interarticular  fibro-cartilages  are  as  follows  : 

1.  The  sterno-clavicular  joint. 

2.  The  acromio-clavicular  joint  (inconstant). 

3.  The  triangular  fibro-cartilage  of  the  inferior  radio-ulnar 
articulation  is  to  be  regarded  as  an  interarticular  fibro-cartilage 
between  the  ulna  and  cuneiform  bone  at  the  radio-carpal  joint. 

The  shoulder-joint  has  a  circumferential  fibro-cartilage,  namely, 
the  glenoid  ligament. 


GUIDE  TO  THE  UPPER  LIMB. 

The  Back. — To  remove  the  skin,  the  following  incisions  may  be  made :  one 
along  the  middle  line  from  the  seventh  cervical  spine  to  the  second  sacral  spine  ; 
another  from  the  upper  end  of  this  incision  outwards  to  the  acromion  process, 
and  thence  downwards  over  the  back  of  the  shoulder  in  a  curved  manner  to 
meet  the  posterior  fold  of  the  axilla  ;  and  a  third  from  the  lower  end  of  the 
mesial  incision  outwards  along  the  iliac  crest.  The  cutaneous  nerves  will  be 
found  near  the  spines  of  the  upper  six  thoracic  vertebra;  and  near  the  angles 
of  the  lower  six  ribs.  Three  branches  from  the  first  three  lumbar  nerves  are 
to  be  shown  descending  over  the  iliac  crest  to  the  gluteal  region. 

The  trapezius  muscle  is  to  be  cleaned,  and,  in  doing  so,  as  well  as  in  the  deep 
stages  of  this  dissection,  it  is  advisable  that  the  dissector  of  the  upper  limb 
should  work  in  concert  with  the  dissector  of  the  head.  The  spinal  accessory 
nerve  will  be  found  passing  beneath  the  anterior  border  of  the  trapezius. 
The  latissimus  dorsi  is  next  to  be  cleaned,  and  turning  backwards  round  its 
outer  border  will  be  found  the  posterior  offsets  of  the  lateral  cutaneous  branches 
of  the  intercostal  nerves.  Between  the  contiguous  borders  of  the  latissimus 
dorsi  and  obliquus  externus  abdominis,  just  above  the  centre  of  the  iliac  crest, 
the  triangle  of  Petit  is  to  be  shown.  The  region  between  the  trapezius, 
latissimus  dorsi,  and  base  of  the  scapula,  and  the  parts  contained  therein,  are 
to  be  studied.  The  trapezius  is  to  be  divided  about  i  inch  from  the  spines  of 
the  vertebrae,  and  the  spinal  accessory  nerve,  with  branches  of  the  third  and 
fourth  cervical  nerves,  and  the  superficial  cervical  artery,  are  to  be  dissected  on 
its  deep  surface.  The  latissimus  dorsi  is  to  be  divided  by  an  incision  carried 
downwards  from  its  upper  border  about  3  inches  from  the  spines  of  the  vertebrae 
to  the  back  part  of  the  iliac  crest  internal  to  the  iliac  origin  of  the  muscle, 
so  as  to  leave  undisturbed  its  slips  of  origin  from  the  lower  three  or  four  ribs, 
as  well  as  its  iliac  origin.  In  reflecting  inwards  the  inner  portion  of  the  muscle 
care  is  to  be  taken  not  to  injure  the  serratus  posticus  inferior,  and,  in  turning 
outwards  the  outer  portion,  the  serratus  magnus  is  not  to  be  interfered  with. 

The  levator  anguli  scapulae  and  rhomboid  muscles  are  to  be  dissected,  and 
the  nerve  to    the  rhomboids  is  to  be  looked  for  deeply  between    these  two 


THE   UPPER  LIMB  387 

muscles  about  1  inch  from  the  base  of  the  scapula.  The  disposition  of  the 
rhomboideus  niajor  at  its  insertion  is  to  be  noted,  and  the  fibrous  band  or  arch 
shown.  The  levator  anguli  scapulae  is  to  be  divided  about  its  centre,  and  the 
rhomboids  about  i  inch  from  the  spines  of  the  vertebrae,  which  will  bring  into 
view  the  posterior  scapular  artery-  lying  close  to  the  base  of  the  scapula.  A 
branch  to  the  levator  anguli  scapute  from  the  nerve  to  the  rhomboids  is 
to  be  looked  for,  and  a  very  limited  view  will  be  obtained  of  the  posterior 
belly  of  the  omo-hyoid  at  the  vipper  border  of  the  scapula.  In  association 
with  it  the  suprascapular  nerve  and  artery  may  just  be  seen,  but  this  dissection 
is  not  to  be  pushed. 

The  serratus  posticus  superior  is  next  to  be  dissected,  followed  by  that  of 
the  serratus  posticus  inferior,  and  before  reflecting  these  muscles  the  vertebral 
aponeurosis  is  to  be  studied,  and  the  posterior  lamina  of  the  lumbar  apo- 
neurosis, which  gives  origin  to  the  latissimus  dorsi  and  serratus  posticus 
inferior.  At  this  stage  the  internal  or  deep  surface  of  the  serratus  magnus 
is  to  be  examined.  The  serratus  posticus  superior  is  to  be  cut  about  i  inch 
from  the  spines  of  the  vertebrae,  and  each  serration  of  the  serratus  posticus 
inferior  is  to  be  divided  just  below  the  rib  into  which  it  is  inserted.  The 
vertebral  aponeurosis  is  also  to  be  carefully  removed.  In  this  manner  the 
erector  spinae  muscle  is  exposed.  Before  dissecting  this  muscle,  however, 
the  splenius  is  to  be  studied,  in  concert  with  the  dissector  of  the  head,  and 
divided  about  i  inch  from  its  origin.  Underneath  the  splenius  will  be  found 
the  complexus,  the  inner  portion  of  which  is  known  as  the  biventer  cervicis, 
and  external  to  the  complexus  is  the  narrow,  ribbon-like  trachelo-mastoid  or 
transversalis  capitis.  The  dissector  should  now  replace  over  the  lower  part 
of  the  erector  spinae  the  posterior  lamina  of  the  lumbar  aponeurosis,  having 
attached  to  it  the  latissimus  dorsi  and  serratus  posticus  inferior.  At  the  outer 
border  of  the  erector  spinae  he  should  notice  a  portion  of  the  middle  lamina  of 
the  lumbar  aponeurosis,  of  which  more  will  come  into  view  by  raising  the  outer 
border  of  the  muscle.  He  will  thus  see  that  the  lower  part  of  the  erector 
spinae  is  enclosed  in  a  sheath,  the  posterior  wall  of  which  is  formed  by  the  pos- 
terior lamina,  and  the  anterior  wall  by  the  middle  lamina,  of  the  lumbar 
aponeurosis.  The  anterior  lamina  is  not  visible  at  this  stage.  The  obliquus 
internus  abdominis  may  be  seen  to  arise  from  the  lumbar  aponeurosis  between 
the  iliac  crest  and  the  last  rib. 

The  dissection  of  the  erector  spinae  is  now  to  be  proceeded  with.  The 
separation  between  the  outer  and  middle  columns  of  the  muscle  will  be  ap- 
parent a  little  below  the  twelfth  rib  as  a  cellular  interval,  through  which  nerves 
emerge,  and  in  line  with  which,  higher  up,  nerves,  accompanied  bv  arteries 
and  veins,  also  appear.  Dealing  lirst  with  the  outer  column,  and  dissecting  it 
from  below  upwards,  the  slips  of  insertion  of  the  ilio-costalis  into  the  angles  of 
the  lower  six  ribs  are  to  be  shown.  These  are  then  to  be  turned  outwards,  and 
the  slips  of  origin  of  the  musculus  accessorius  lying  internal  to  them  are  to  be 
displayed,  followed  by  the  slips  of  insertion  of  that  muscle  into  the  upper  ribs. 
The  latter  having  been  turned  outwards,  the  slips  of  origin  of  the  cervicalis 
ascendens  will  be  found,  and  this  muscle  is  to  be  followed  up  into  the  neck, 
where  its  three  slips  of  insertion  are  to  be  brought  out.  In  dealing  with  the 
middle  column  the  dissector  should  first  artificially  separate  from  it  the  inner 
column,  the  connection  between  the  two  being  very  close,  and  he  may  at  once 
dispose  of  the  inner  column  or  spinalis  dorsi.  Its  four  fleshy  and  tencUnous 
origins  below  should  be  shown,  and  its  tendons  of  insertion  above,  varying 
from  four  to  eight  in  number.  The  series  of  arches  formed  by  the  tendons  of 
this  muscle  should  be  noted.  The  middle  column  is  next  to  be  dissected,  and 
the  two  series  of  insertions  of  the  longissimus  dorsi  shown,  the  outer,  fleshy, 
passing  to  the  luml)ar  transverse  processes  and  ril)s,  and  the  inner,  round  and 
tendinous,  passing  to  the  lumbar  accessory  processes  and  tlioracic  transverse 

f)rocesses.  At  the  upper  part  of  the  l)ack  the  dissector  will  find  tliat  the 
ongissimus  dorsi  is  ]>rolongefl  into  llie  neck  I)y  tin-  transversalis  cervicis,  and 
to  the  head  l>y  tlu;  Irachelcj-mastoid.  It  is  at  this  stage  that  the  complexus 
is  most  advantageously  studied.  This  muscle  having  been  cut  high  up  by  the 
dissector  of  the  head,  the  semispinalis  dorsi  and  semispinalis  colli  are  to  be 

25—2 


388  A  MANUAL  OF  ANATOMY 

dissected.  The  semispinales  and  longissimus  dorsi  having  been  removed,  the 
multiiidTis  spinse  is  to  be  studied,  and  an  effort  made  to  show  its  deepest  fibres, 
called  the  rotatores  spinae.  The  levatores  costarum  are  to  be  carefully  dissected, 
and  the  intertransversales  and  interspinales  are  to  be  looked  to,  chiefly  in 
the  cervical  and  lumbar  regions. 

Pectoral  Region  and  Axillary  Space. — To  remove  the  skin,  the  following 
incisions  should  be  made  :  a  mesial  incision  along  the  sternum  ;  another  from 
the  upper  end  of  this  along  the  clavicle  to  the  acromion  process,  and  thence 
downwards  over  the  front  of  the  shoulder  to  the  inner  side  of  the  arm  close  to 
the  anterior  fold  of  the  axilla  ;  and  a  third  transversely  outwards  from  the 
lower  end  of  the  sternum.  In  the  case  of  a  female  subject,  a  circular  incision 
should  be  made  around  the  margin  of  the  areola.  In  removing  the  skin 
from  over  the  mammary  gland  the  fibrous  processes,  known  as  the  ligamenta 
suspensoria  of  Cooper,  which  pass  between  the  superficial  fascia  in  front 
of  the  gland  and  the  skin,  are  to  be  noted.  The  following  cutaneous  nerves 
are  to  be  displayed:  (i)  the  suprasternal,  supraclavicular,  and  supra-acromial 
branches  of  the  cervical  plexus,  which  descend  over  the  clavicle  beneath  the 
platysma  myoides  ;  (2)  the  anterior  cutaneous  branches  of  the  intercostal 
nerves,  which  emerge  through  the  upper  six  intercostal  spaces  close  to  the 
sternum  ;  and  (3)  the  anterior  offsets  of  the  lateral  cutaneous  branches  of 
intercostal  nerves  below  the  second,  which  turn  round  the  anterior  fold  of  the 
axilla. 

If  the  subject  is  a  female,  the  mammary  gland  should  now  receive  careful 
attention.  Its  relation  to  the  superficial  fascia,  which  ensheathes  it,  is  to 
be  studied,  and  also  its  relation  to  the  deep  fascia  covering  the  pectorahs 
major.  The  thin  skin  of  the  areola  is  to  be  carefully  raised  towards  the 
nipple,  and  the  galactophorous  ducts,  each  presenting  a  dilatation  or  ampulla, 
are  to  be  shown.  An  endeavour  should  be  made  to  display  the  glandular 
structure  and  locuU. 

The  pectoralis  major  and  anterior  portion  of  the  deltoid  are  to  be  dissected, 
and  in  the  groove  between  the  two  the  cephahc  vein  and  humeral  branch  of 
the  acromio- thoracic  artery  are  to  be  shown.  Lying  deeply  in  the  upper  part 
of  this  groove,  just  below  the  clavicle,  the  infraclavicular  glands,  two  or  three 
in  number,  are  to  be  looked  for.  The  clavicular  part  of  the  pectoraUs  major 
should  now  be  divided  and  reflected.  In  doing  so,  the  cephalic  vein,  external 
anterior  thoracic  nerve,  and  branches  of  the  acromio- thoracic  artery  are  to 
be  presei-ved.  The  region  now  being  dissected  (infraclavicular)  lies  between 
the  clavicle,  pectoralis  minor,  and  upper  border  of  the  sterno-costal  portion 
of  the  pectorahs  major.  The  costo-coracoid  membrane,  which  is  a  part  of 
the  clavi-pectoral  fascia,  is  to  be  shown,  and  the  stout  portion  of  it,  called 
the  costo-coracoid  hgament,  is  to  be  noted. 

Having  studied  the  connections  of  the  costo-coracoid  membrane  and  the 
various  structures  piercing  it,  the  membrane,  along  with  the  axillary  sheath 
beneath  it,  is  to  be  carefully  removed,  and  the  first  part  of  the  axillary  artery, 
with  its  branches,  the  axillary  vein,  and  the  trunks  of  the  brachial  plexus  are 
to  be  displayed.  The  internal  anterior  thoracic  nerve  will  be  found  coming  for- 
wards between  the  artery  and  the  vein,  and  a  communication  between  it  and 
the  external  anterior  thoracic  nerve  is  to  be  looked  for  over  the  artery.  The 
posterior  thoracic  nerve,  which  hes  behind  the  artery,  is  to  be  carefully 
preserved.  The  removal  of  the  costo-coracoid  membrane  will  also  expose  the 
subclavius  muscle.  Without  further  disturbing  the  pectorahs  major  mean- 
while, the  axillary  space  is  now  to  be  dissected  from  below.  The  axillary 
fascia  forming  the  floor  of  the  space,  and  its  relations  to  the  fascial  investments 
of  the  pectoralis  major  and  latissimus  dorsi  and  fascia  of  the  arm  are  to  be 
noted.  The  fascia  will  be  seen  to  be  drawn  up  towards  the  space,  this  being 
due  to  the  insertion  of  the  clavi-pectoral  fascia  into  its  upper  surface.  The 
axillary  fascia  having  been  dissected,  the  adipose  tissue  in  the  space  is  to  be 
removed  with  the  greatest  care.  The  lateral  cutaneous  branches  of  the  inter 
costal  nerves  (except  the  first)  will  be  found  on  the  inner  wall  between  the 
serrations  of  the  serratus  magnus.  The  lateral  cutaneous  branch  of  the  second 
intercostal  is  to  be  followed  as  the  intercosto-humeral  nerve  across  the  space 


THE  UPPER  LIMB  389 

to  the  inner  and  back  part  of  the  arm.  The  lateral  cutaneous  branches  of  the 
succeeding  intercostal  nerves  are  to  be  shown  in  two  divisions — anterior  and 
posterior.  The  axillary  glands  are  to  be  carefully  looked  for.  They  will  be 
found  in  three  groups,  namely,  pectoral,  within  the  anterior  fold  and  on  the 
adjacent  part  of  the  inner  wall ;  subscapular,  on  the  posterior  wall ;  and  external, 
on  the  outer  wall.  The  posterior  thoracic  nerve  is  to  lie  followed  out  upon  the 
serratus  magnus,  the  long  thoracic  artery  will  be  found  along  the  lower  border 
of  the  pectoralis  minor,  and  the  subscapular  artery  on  the  posterior  wall. 
The  dorsalis  scapulae  branch  of  the  subscapular  artery  is  to  be  shown.  The 
alar  thoracic  is  seldom  a  special  artery.  The  middle  or  long  and  lower  sub- 
scapular nerves  will  be  found  on  the  posterior  wall,  the  former,  with  the 
subscapular  artery,  going  to  the  latissimus  dorsi,  the  latter,  farther  out, 
suppljang  the  teres  major  and  adjacent  part  of  the  subscapularis.  The  upper 
or  short  subscapular  nerve  should  not  be  looked  for  at  present,  as  it  lies  too 
liigh  up.  The  structures  along  the  outer  wall  are  next  to  be  shown,  namely, 
the  axillary  artery,  giving  off  its  subscapular,  anterior  circumflex,  and  posterior 
circumflex  branches  ;  the  axillary  vein  ;  and  the  nerves  arising  from  the  cords 
of  the  brachial  plexus.  The  internal  cutaneous  branch  of  the  musculo-spiral 
nerve  should  be  shown  at  this  stage,  and  preserved.  When  the  tributaries 
of  the  axillary  vein  have  been  noted  in  the  course  of  the  foregoing  dissection 
they  should  be  removed. 

The  sterno-costal  portion  of  the  pectoralis  major  is  now  to  be  divided  and 
reflected,  in  doing  which  twigs  of  the  internal  anterior  thoracic  nerve  will 
be  seen  entering  its  deep  surface,  after  having  pierced  the  pectoralis  minor. 
The  latter  muscle  is  now  to  be  dissected,  the  fascia,  removed  in  preparing  it, 
being  continuous  above  with  the  costo-coracoid  membrane,  and  being  inserted 
below  into  the  upper  surface  of  the  axillary  fascia.  The  internal  anterior 
thoracic  nerve  is  to  be  shown  entering  the  deep  surface  of  the  muscle.  The 
pectoralis  minor  having  been  cut,  the  axillary  space  will  be  fully  exposed.  The 
second  part  of  the  axillary  artery  is  to  be  dissected,  and  it  will  be  found,  as 
a  rule,  to  give  off  the  long  thoracic,  but  the  alar  thoracic  is  very  inconstant. 
The  cords  of  the  brachial  plexus  and  their  relation  to  the  second  part  of  the 
artery  are  to  be  noted,  and  the  upper  or  short  subscapular  nerve  may  now 
be  seen  at  the  upper  part  of  the  posterior  wall  of  the  space,  where  it  immedi- 
ately enters  the  upper  part  of  the  subscapularis.  The  origins  of  the  branches 
of  the  cords  of  the  brachial  plexus  are  to  be  shown  as  follows  :  external 
*  anterior  thoracic,  musculo-cutaneous,  and  outer  root  of  the  median  from  the 
outer  cord  ;  internal  anterior  thoracic,  lesser  internal  cutaneous  or  nerve  of 
Wrisberg,  the  internal  cutaneous,  inner  root  of  the  median,  and  ulnar  from  the 
inner  cord  ;  and  the  three  subscapular  nerves,  circumflex,  and  musculo-spiral 
from  the  posterior  cord. 

The  next  duty  of  the  dissector  is  to  study  the  sterno-clavicular  joint.  There- 
after the  clavicle  is  to  be  sawn  through  at  its  centre,  and  the  subclavius  muscle 
divided.  At  this  stage  the  dissectors  of  the  upper  limb  and  head  should  work 
in  concert.  A  full  view  will  be  ol)tained  of  the  continuity  between  the  sub- 
clavian and  axillary  arteries,  and  the  nerve  trunks  and  individual  nerves  of 
the  brachial  ])le.\us,  as  well  as  the  supra- clavicidar  branches  of  that  ]:)lexus. 
The  sujjrascapular  artery  and  nerve,  and  the  posterior  belly  of  the  omo-hyoid 
will  also  l)e  seen.  The  vessels  and  nerves  are  then  all  to  be  included  in  two 
ligatures  placed  i  inch  apart,  and  divided  between  them,  and  the  lower  ligature 
is  to  be  firmly  secured  to  the  outer  cut  end  of  the  clavicle.  The  serratus  magnus 
is  to  be  studied,  and  it  will  lie  put  upon  the  stretch  if  the  shoulder  is  pressed 
outwards.  The  limb  is  then  to  be  removed  by  dividing  the  serratus  magnus, 
posterior  belly  of  the  omo-hyoid,  and  levator  anguli  scapuLne,  if  the  latter  has 
not  been  already  cut. 

Scapular  Region. — After  removal  of  the  limb,  the  dissector  is  to  trim  the 
various  scapular  muscles  already  dissected,  and  the  arrangement  of  the  tendon 
of  insertion  of  the  pectoralis  major  is  to  be  shown.  The  shoulder  being  sup- 
ported on  a  block,  the  skin  is  to  be  removed  from  over  the  deltoid,  and  the 
cutaneous  nerves  shown,  namely,  the  supra-acromial  over  the  upper  third, 
and  a  large  cutaneous  branch  of    the  circuinlle.K  turning  round  the  posterior 


390  A   MANUAL  OF  ANATOMY      ■ 

border  of  the  muscle  near  its  centre.  In  cleaning  this  border  the  relation  to  it 
of  the  deep  fascia  over  the  infraspinatus  is  to  be  observed.  The  deltoid  having 
been  fully  dissected,  and  twigs  of  the  circumflex  nerve  which  pierce  it  having 
been  noted,  the  muscle  is  to  be  divided  about  i  inch  below  its  origin.  In 
turning  it  down  the  subacromial  bursa  and  the  circumflex  nerve  and  posterior 
circumflex  artery  are  to  be  shown,  the  latter  two  entering  its  deep  surface. 

The  infraspinatus,  teres  minor,  teres  major,  and  long  head  of  the  triceps  are 
then  to  be  dissected,  and  the  ganghform  enlargement  on  the  branch  of  the 
circumflex  nerve  to  the  teres  minor  is  to  be  observed.  The  quadrangular  and 
triangular  muscular  spaces,  with  their  contents,  are  to  be  exposed,  and  the 
substitution  of  the  subscapularis  as  a  boundary  in  front  for  the  teres  minor 
behind  is  to  be  noted.  The  dorsalis  scapulae  artery  is  to  be  shown  winding 
round  the  axillary  border  of  the  scapula  through  the  origin  of  the  teres 
minor.  The  supraspinatus  is  next  to  he  dissected,  and,  to  follow  the  muscle 
to  its  insertion,  the  acromion  process  may  be  sawn  through.  At  the  upper 
border  of  the  muscle  will  be  found  the  posterior  belly  of  the  omo-hyoid  and  the 
suprascapular  nerve  and  artery.  The  subscapularis  is  to  be  cleaned,  and  at 
this  stage  the  upper  or  short  subscapular  nerve  will  be  fully  seen. 

The  supraspinatus,  infraspinatus,  and  teres  minor  are  to  be  stripped  carefully 
from  the  bone  and  dissected  up  to  their  insertions,  in  doing  which  the  intimate 
connection  between  their  tendons  and  the  upper  and  back  parts  of  the  capsule 
of  the  shoulder-joint  will  arrest  attention.  Between  the  infraspinatus  tendon  and 
the  capsule  a  small  bursa  may  be  found.  The  careful  removal  of  these  muscles 
will  allow  the  dissector  to  follow  out  the  suprascapular  artery  and  nerve,  and 
the  dorsahs  scapulae  artery.  The  subscapularis  is  also  to  be  stripped  from  the 
bone  and  dissected  to  its  insertion,  to  do  which  the  muscle  must  be  raised 
from  beneath  the  coraco-brachialis  and  short  head  of  the  biceps.  The  close 
connection  between  its  tendon  and  the  front  of  the  capsule  is  to  be  noted,  as 
well  as  the  opening  in  the  capsule  through  which  the  synovial  membrane 
protrudes  to  form  the  subscapular  bursa.  The  teres  major  and  latissimus 
dorsi  are  to  be  followed  to  their  insertions,  the  varying  relations  between  the 
two  are  to  be  made  clear,  the  intervening  bursa  shown,  and  in  some  cases  a 
small  bursa  behind  the  tendon  of  the  teres  major  close  to  the  bone.  Before 
leaving  this  region  the  dissector  should  carefully  study  the  scapular  anasto- 
moses of  arteries,  the  muscular  relations  of  the  capsule  of  the  shoulder-joint, 
and  the  actions  of  the  scapular  muscles,  with  their  nerve-supply. 

Cutaneous  Nerves  and  Veins  of  the  Arm  and  Forearm. — The  skin  should  be* 
at  once  reflected  as  low  as  the  wrist  by  a  median  incision  down  the  front  of 
the  limb,  and  transverse  incisions  at  the  elbow  and  wrist.  In  reflecting  it 
from  over  the  back  of  the  olecranon  process  the  subcutaneous  bursa,  there 
situated,  is  to  be  attended  to.  The  following  cutaneous  nerves  are  to  be  fol- 
lowed out  to  their  distribution,  care  being  taken  to  preserve  the  cutaneous 
veins  :  (i)  the  intercosto-humeral  to  the  inner  and  back  part  of  the  arm  in 
its  upper  half  ;  (2)  the  internal  cutaneous  of  the  musculo-spiral  to  the  back  of 
the  arm  ;  (3)  the  nerve  of  Wrisberg  to  the  lower  half  of  the  arm  on  its  inner 
aspect  ;  (4)  twigs  of  the  internal  cutaneous  to  the  front  of  the  arm  in  its  upper 
part  ;  and  (5)  the  upper  external  cutaneous  branch  of  the  musculo-spiral 
(which  appears  a  little  below  the  centre  of  the  outer  side  of  the  arm)  to  the 
outer  side  and  front  of  the  arm  over  about  its  lower  half.  At  the  junction  of 
the  upper  two-thirds  and  lower  third  of  the  arm  on  its  inner  side  the  internal 
cutaneous  nerve  will  be  found  piercing  the  deep  fascia  in  two  divisions,  separ- 
ately or  conjointly,  and  from  this  point  the  two  divisions,  anterior  and 
posterior,  are  to  be  followed  downwards  along  the  inner  part  of  the  forearm, 
as  low  as  the  wrist  in  the  case  of  the  anterior.  The  lower  external  cutaneous 
branch  of  the  musculo-spiral  is  to  be  followed  from,  the  outer  side  of  the  arm, 
a  little  below  the  centre,  down  the  back  of  the  outer  side  of  the  forearm  as  low 
as  the  wrist.  The  cutaneous  part  of  the  musculo-cutaneous  will  be  found  at 
the  outer  border  of  the  biceps  a  little  above  the  elbow,  and  it  is  to  be  traced 
down  the  outer  side  of  the  forearm  as  low  as  the  wrist  in  two  divisions,  anterior 
and  posterior. 

In  front  of  the  forearm,  just  below  the  centre  and  internal  to  the  middle  line, 


THE  UPPER  LIMB  391 

a  cutaneous  branch  of  the  ulnar  nerve  may  he  met  with,  and  towards  the  wrist 
the  pahnar  cutaneous  branches  of  the  median  and  uhiar  are  to  be  shown.  In 
the  lower  third  of  the  forearm,  posteriorly  and  on  its  outer  aspect,  the  radial 
nerve  is  to  be  shown,  as  well  as  the  dorsal  branch  of  the  ulnar  nerve  on  its 
inner  aspect.  The  cutaneous  veins  to  be  dissected  are  the  radial,  median,  and 
anterior  and  posterior  ulnar  veins  in  the  forearm  ;  the  median  basilic  and  median 
cephalic  at  the  bend  of  the  elbow,  with  the  deep  median  joining  the  superficial 
median  close  to  its  termination  ;  and  the  basilic  and  cephalic  in  the  arm,  the 
basihc  being  superficial  to  the  deep  fascia  in  the  lower  half,  but  subsequently 
piercing  it,  and  the  cephalic  being  superficial  throughout.  In  connection  with 
the  median  basilic  vein  the  semilunar  fascia  of  the  biceps  is  to  be  shown,  and 
one  or  two  supracondylar  glands  are  to  be  carefully  looked  for  a  little  above 
the  internal  epicondyle,  close  to  the  basilic  vein. 

Front  and  Inner  Side  of  the  Brachial  Region. — The  deep  fascia  of  the  arm  is  to 
be  studied,  and,  as  the  dissection  proceeds,  the  external  and  internal  inter- 
muscular septa,  with  the  structures  related  to  them,  are  to  be  noted.  The 
biceps  and  coraco-brachialis  are  to  be  dissected,  and,  in  connection  with  the 
tendon  of  insertion  of  the  latter  muscle,  a  fibrous  band  should  be  looked  for 
passing  upwards  to  the  humerus  below  the  small  tuberosity,  and  forming  an 
arch  over  the  latissimus  dorsi  and  teres  major.  The  internal  brachial  ligament 
of  Struthers  is  to  be  looked  for,  extending  from  the  humerus  near  the  insertion 
of  the  teres  major  to  the  internal  epicondyle.  The  musculo-cutaneous  nerve 
is  to  be  show^n  piercing  the  coraco-brachialis,  and,  by  raising  the  biceps,  the 
nerve  is  to  be  followed  between  that  muscle  and  the  brachiahs  anticus  to  the 
outer  border  of  the  biceps,  where  it  becomes  cutaneous,  and  its  muscular 
branches  are  to  be  shown.  It  may  be  found  to  give  a  communicating  branch 
to  the  median.  The  semilunar  fascia  of  the  biceps  is  to  be  carefully  dissected, 
and  its  relation  to  the  brachial  artery  and  median  basilic  vein  is  to  be  observed. 

The  brachial  artery  is  next  to  be  dissected,  and  the  vena;  comites  on  either 
side  of  it  shown.  These  will  be  found  to  join  above,  and  terminate  in  the  lower 
part  of  the  axillary  vein.  The  median  nerve  is  to  be  shown  lying  at  first  on 
the  outer  side  of  the  artery,  then  crossing  it  just  below  the  centre  of  the  arm, 
and  thereafter  lying  on  its  inner  side.  It  gives  off  no  branches  in  the  arm, 
but  it  may  receive  one  from  the  musculo-cutaneous.  The  branches  of  the 
brachial  artery  are  to  be  shown  as  follows  :  (i)  the  superior  profunda  arises 
high  up  from  the  inner  and  back  part  of  the  vessel,  and  accompanies  the  mus- 
culo-spiral  nerve  to  the  back  of  the  arm  ;  (2)  the  inferior  profunda  arises  from 
the  inner  side  a  little  lower  down  than  the  preceding,  and  accompanies  the 
ulnar  nerve  through  the  internal  intermuscular  septum  to  the  interval  between 
the  internal  epicondyle  and  the  olecranon  ;  (3)  the  nutrient  or  medullary  artery 
arises  from  the  inner  side  about  the  lower  border  of  the  tendon  of  insertion 
of  the  coraco-bracliialis,  and  passes  downwards  to  enter  the  medullary  foramen 
of  the  humerus  ;  (4)  the  anastomotica  magna  arises  from  the  inner  side  about 
2  inches  above  the  elbow,  and  divides  into  two  branches — anterior,  passing 
downwards  in  front  of  the  internal  epicondyle  beneath  the  pronator  radii 
teres,  and  posterior,  piercing  the  internal  intermuscular  septima  to  reacli  the 
interval  lietween  the  internal  epicondyle  and  the  olecranon  ;  and  (5)  several 
muscular  branches  arising  from  the  outer  side  of  tlie  vessel. 

The  musculo-spiral  nerve  is  to  be  shown  lying,  for  a  little,  behind  the  upper 
part  of  the  lirachial  artery,  and  the  branches  whicli  it  Irere  gives  off,  namely, 
internal  cutaneous  to  the  back  of  the  arm,  and  muscular  to  the  long  and 
internal  heads  of  the  triceps,  are  to  be  noted.  One  of  the  latter  descends  with 
the  ulnar  nerve,  as  the  ulnar  collateral  nerve  of  Krause,  to  enter  the  internal 
head  of  the  muscle  low  down.  The  ulnar  nerve  is  to  be  dissected  as  low  as  the 
internal  e])icondyle  and  the  olecranon,  and  it  is  to  be  shown  ])iercing  the 
internal  intermuscular  septum.  It  gives  off  no  branches  in  the  arm.  The 
internal  cutaneous  nerve  and  the  nerve  of  Wrisberg  are  also  to  be  noted.  The 
brachialis  anticus  is  to  be  dissected  by  displacing  the  Ijiceps  outwards,  and  it  is 
to  be  separated  from  the  brachio-radialis.  In  this  way  a  part  of  the  musculo- 
spinal nerve  will  be  exposed,  and  it  is  to  b(.'  followed  carefully  downwards  to 
near  the  external  epicondyU;,  wher(;  its  two  linninal  branches,  radial  and 


392  A   MANUAL  OF  ANATOMY 

posterior  interosseous,  are  to  be  shown.  In  this  part  of  its  course  the  nerve 
will  be  found  to  furnish  branches  to  the  brachio-radialis  and  extensor  carpi 
radialis  longior,  and  a  twig  to  the  brachialis  anticus,  the  latter  arising  liigh 
up  in  the  spiral  groove.  Descending  with  the  niusculo-spiral  nerve  in  this 
groove  will  be  found  the  anterior  terminal  branch  of  the  superior  profunda 
artery,  and  coming  up  from  below  to  anastomose  with  it  a  branch  of  the  radial 
recurrent. 

The  anticubital  space  or  triangular  hollow  in  front  of  the  elbow  is  next 
to  be  dissected,  and  its  roof,  floor,  boundaries,  and  contents  carefully  studied. 
If  the  brachio-radialis  is  held  aside,  the  posterior  interosseous  nerve  will 
be  seen  piercing  the  supinator  radii  brevis  ;  and,  if  the  superficial  head  of 
the  pronator  radii  teres  is  raised,  the  anterior  ulnar  recurrent  artery,  of 
small  size,  will  be  found  ascending  to  the  front  of  the  internal  epicondyle, 
where  it  anastomoses  with  the  anterior  branch  of  the  anastomotica  magna. 
The  mode  of  insertion  of  the  tendon  of  the  bicepis  is  to  be  carefully  noted,  and 
its  action  in  this  connection  studied. 

Back  of  the  Brachial  Region. — The  triceps  is  to  be  dissected,  and  its  three 
heads  clearly  shown.  The  long  head  is  obvious,  but  the  external  and  internal 
heads  require  careful  dissection.  The  dissector  should  pull  upon  the  musculo- 
spiral  nerve  to  make  evident  its  winding  course  round  the  back  of  the  humerus, 
and  he  should  then  make  an  incision  through  the  muscle  over  the  course  of 
the  nerve,  avoiding  its  long  head.  When  the  cut  parts  of  the  muscle  are 
separated,  the  spiral  groove  of  the  humerus  is  laid  bare,  with  the  musculo- 
spiral  nerve  and  superior  profunda  artery  lying  in  it.  The  portion  of  the 
muscle  above  and  external  to  the  groove  is  the  external  head,  and  the  small, 
peaked  portion  inside  the  groove  and  all  the  fibres  arising  from  the  back  of 
the  humerus  below  the  groove  represent  the  internal  head. 

The  branches  of  the  musculo-spiral  nerve  behind  the  humerus  are  to  be 
shown,  and  one  long  branch  to  the  anconeus,  which  descends  in  the  internal 
head  of  the  triceps,  is  to  be  followed  out.  The  nerve,  on  leaving  the  spiral 
groove,  will  be  seen  to  pierce  the  external  intermuscular  septum  from  behind 
forwards,  along  with  the  anterior  branch  of  the  superior  profunda  artery.  This 
artery  is  also  to  be  dissected,  and  its  posterior  terminal  branch  is  to  be  shown 
descending  behind  the  extei^nal  intermuscular  septum  to  the  back  of  the 
external  epicondyle,  where  it  anastomoses  with  the  posterior  interosseous 
recurrent.  The  internal  head  of  the  triceps  may  now  be  cut  into  interiorly, 
in  order  to  show  its  deepest  fibres,  under  the  name  of  the  subanconeus,  taking 
insertion  into  the  back  part  of  the  capsule  of  the  elbow- joint. 

Acromio-clavicular  Joint.  —  In  connection  with  this  joint  the  coraco- 
clavicular  ligament  is  to  be  displayed  in  two  parts — conoid  and  trapezoid — 
and  between  these  will  be  found  a  little  fat  and  a  small  bursa.  The  ligaments 
of  the  joint  itself  are  next  to  be  dissected,  and,  when  the  joint  is  opened,  an 
incomplete  interarticular  fibro-cartilage  may  be  found  within  it  at  the  upper 
part. 

Special  Ligaments  of  the  Scapula. — The  suprascapular  or  transverse  ligament 
is  to  be  made  evident,  with  the  suprascapular  nerve  passing  backwards 
beneath  it,  the  suprascapular  artery  over  it,  and  fibres  of  the  posterior  belly  of 
the  omohyoid  arising  from  it.  The  coraco-acromial  or  deltoid  Ugament  is 
next  to  be  dissected,  and  its  relation  to  the  capsule  of  the  shoulder-joint  care- 
fully noted.  The  spino-glenoid  ligament  is  to  be  shown  passing  between  the 
outer  border  of  the  spine  and  the  adjacent  part  of  the  margin  of  the  glenoid 
cavity.  It  will  be  seen  to  bridge  over  the  suprascapular  artery  and  nerve  on 
their  way  to  the  infraspinous  fossa. 

Shoulder-Joint. — The  dissector  should  first  revise  the  subacromial  bursa 
and  the  muscular  relations  of  the  capsule  of  this  joint.  The  capsular  ligament 
is  then  to  be  studied,  and  the  coraco-humeral  ligament  is  to  be  noted  incor- 
porated with  its  upper  aspect.  Two  openings  in  the  capsule  are  to  be 
observed.  One  is  situated  in  front,  behind  the  upper  border  of  the  tendon 
of  the  subscapularis,  and  through  this  opening  the  synovial  membrane  will 
be  found  protruding  to  form  the  subscapular  bursa.  The  other  opening  is 
situated  between  the  tuberosities  of  the  humerus,  at  the  entrance  to  the  bi- 


THE  UPPER  LIMB  393 

cipital  groove,  this  being  for  the  passage  of  the  long  tendon  of  the  biceps. 
The  transverse  humeral  ligament  will  be  found  bridging  over  this  part  of  the 
bicipital  groove.  The  joint  should  now  be  opened  by  removing  the  posterior 
part  of  the  capsule,  and  the  three  gleno-humeral  hganients  are  to  be  looked  for. 
They  are  situated  on  the  inner  and  anterior  aspect  of  the  capsule.  The  front 
part  of  the  capsule  should  now  be  removed  and  the  glenoid  ligament  examined. 
The  tendon  of  the  long  head  of  the  biceps,  as  it  arches  over  the  head  of  the 
humerus,  is  to  be  noted,  and  its  relation  to  the  glenoid  hgament  at  the  apex 
of  the  glenoid  cavity  is  to  be  shown.  The  synovial  membrane  and  movements 
are  then  to  be  studied. 

Front  of  the  Forearm. — The  deep  fascia  is  to  be  examined  and  removed, 
except  the  part  covering  the  muscles  arising  from  the  internal  epicondyle. 
These  muscles  are  to  be  dissected,  from  without  inwards,  in  the  following  order  : 
pronator  radii  teres,  flexor  carpi  radiaUs,  palmaris  longus,  flexor  carpi  ulnaris, 
and  flexor  subhmis  digitorum.  Having  noted  the  common  tendon  of  origin 
of  these  muscles,  what  is  left  of  the  deep  fascia  is  to  be  removed,  and  the  muscles 
carefully  separated  from  each  other  up  to  their  origins.  In  doing  so,  the 
strong  intermuscular  septa  are  to  be  noted.  The  small,  deep  head  of  the 
pronator  radii  teres  is  to  be  displayed,  with  the  median  nerve  passing  between 
the  two  heads  of  the  muscle,  and  the  ulnar  artery  beneath  its  deep  head,  and 
it  should  be  noted  that  the  median  nerve,  which  is  at  first  internal  to  the  ulnar 
artery,  crosses  it  to  get  to  its  outer  side. 

The  muscular  branches  of  the  median  nerve  are  to  be  caught  high  up, 
as  well  as  its  anterior  interosseous  branch,  in  connection  with  which  latter 
care  is  to  be  taken  to  preserve  the  median  branch  of  the  anterior  inter- 
osseous artery,  which  is  usually  of  small  size.  The  ulnar  nerve  is  to  be 
shown  entering  the  forearm  between  the  two  heads  of  the  flexor  carpi  ulnaris, 
where  it  lies  between  the  internal  epicondyle  and  olecranon,  and  gives  off 
articular  twigs  to  the  elbow- joint.  Thereafter  its  branches  to  the  flexor 
carpi  ulnaris  and  inner  portion  of  the  flexor  profundus  digitorum  should 
be  displayed  high  up. 

The  radial  artery  is  next  to  be  dissected  as  low  as  the  wrist,  its  vense 
comites  being  noted.  The  branches  to  be  shown  are  the  radial  recurrent, 
close  to  the  origin,  muscular  down  the  forearm,  and  anterior  radial  carpal 
and  superficial  volar  near  the  wrist.  The  radial  nerve  is  also  to  be  dissected 
until  it  turns  to  the  back  of  the  forearm  beneath  the  tendon  of  the  brachio- 
radiaUs.  The  ulnar  artery  is  then  to  be  dissected  as  low  as  the  wrist,  and, 
descending  over  its  lower  half,  the  palmar  cutaneous  branch  of  the  ulnar 
nerve  is  to  be  preserved.  The  branches  of  the  vessel  to  be  shown  are  the 
anterior  and  posterior  ulnar  recurrents,  the  interosseous  trunk,  soon  divid- 
ing into  anterior  and  posterior  interosseous,  the  former  of  which  gives  off 
the  median  artery  (all  of  these  branches  arising  high  up),  muscular  down  the 
forearm,  and  posterior  and  anterior  ulnar  carpals  near  the  wrist.  The  pos- 
terior interosseous  artery  is  to  be  shown  passing  backwards  between  the  radius 
and  ulna,  and  the  median  branch  of  the  anterior  interosseous  artery  is  to  be 
carefully  studied,  as  it  is  sometimes  of  large  size  and  may  be  continued  into 
the  palm  to  join  the  superficial  palmar  arch.  The  ulnar  nerve  is  to  be  dis- 
sected as  low  as  the  wrist.  Its  occasional  branch  to  the  front  of  the  forearm 
below  the  centre  is  to  be  looked  for,  and  the  palmar  cutaneous  and  dorsal 
l)ranches  are  to  be  shown,  the  former  arising  a  little  below  the  centre  of  the 
forearm  and  the  latter  about  2  inches  above  the  wrist,  after  which  it  turns 
backwards  beneath  the  tendon  of  the  flexor  carpi  ulnaris. 

The  flexor  sublimis  digitorum  is  then  to  be  raised  and  held  aside,  to  show 
the  median  nerve,  with  the  median  artery,  descending  in  close  contact  with 
its  deep  surface  as  far  as  a  little  above  the  wrist,  where  the  nerve  comes  to 
lie  on  the  outer  side  of  the  muscle,  and  gives  off  its  palmar  cutaneous  branch. 
At  this  stage  the  dissector  should  carefully  note  that  the  great  palmar  bursa 
is  prolonged  upwards  round  the  flexor  tendons  for  fully  an  inch  above  the 
anterior  annular  ligament,  and  the  arrangement  of  the  superficial  flexor 
tendons  in  pairs  before  they  pass  beneath  that  ligament  is  to  be  shown.  By 
jfiiUing  upon  the  individual   tendons,  those  of  the  anterior  i)air  will  be  seen 


394  A   MANUAL  OF  ANATOMY 

to  belong  to  the  middle  and  ring  fingers,  and  those  of  the  posterior  pair  to 
the  index  and  little  iingers. 

The  deep  muscles  of  the  front  of  the  forearm  are  next  to  be  dissected,  namely, 
the  flexor  profundus  cligitorum,  flexor  longus  poUicis,  and  pronator  quadratus. 
The  anterior  interosseous  nerve  and  artery,  the  latter  having  two  vena;  comites, 
are  to  be  followed  down  the  front  of  the  interosseous  membrane  beneath  the 
pronator  quadratus.  In  this  latter  situation  the  nerve  should  be  shown  to 
supply  the  pronator  quadratus,  and  give  an  articular  branch  to  the  wrist- 
joint.  The  artery  should  be  here  shown  to  divide  into  anterior  and  pos- 
terior branches,  the  former  descending  to  take  part  in  the  anterior  carpal 
rete,  and  the  latter  piercing  the  interosseous  membrane  to  reach  the  posterior 
carpal  rete. 

Front  of  the  Hand. — The  various  landmarks  are  to  be  carefully  studied. 
Thereafter  the  skin  is  to  be  removed  by  a  median  incision  from  the  centre  of 
the  wrist  to  the  cleft  between  the  middle  and  ring  fingers,  and  a  transverse 
incision  across  the  roots  of  the  fingers.  Median  incisions  are  also  to  be  made 
down  the  centre  of  the  thumb  and  each  finger,  and  the  skin  removed  from  these 
parts.  In  removing  the  skin  from  the  palm  fibrous  processes  will  come  into 
view,  which  connect  it  with  the  central  division  of  the  palmar  fascia.  The 
lobulated  condition  of  the  superficial  fascia  of  the  palm  is  to  be  noted,  and  the 
superficial  transverse  hgament  is  to  be  looked  for  as  a  few  scattered  transverse 
fibres  lying  within  the  skin  at  the  roots  of  the  fingers.  The  palmar  cutaneous 
branches  of  the  median  and  ulnar  nerves  are  to  be  followed  out,  and  twigs  of 
the  radial  nerve,  reinforced  by  twigs  from  the  musculo-cutaneous,  are  to  be 
shown  over  the  thenar  eminence.  The  palmaris  brevis  muscle  is  to  be  care- 
fully dissected,  as  it  is  subcutaneous  and  arranged  in  bundles.  The  expansion 
from  the  tendon  of  the  flexor  carpi  ulnaris  to  the  anterior  annular  ligament  is 
to  be  noted,  as  well  as  the  pisi-uncinate  and  pisi-metacarpal  expansions,  which 
are  known  as  ligaments.  The  ulnar  artery  and  nerve  are  then  to  be  followed 
over  the  anterior  annular  ligament  till  they  disappear  beneath  the  palmaris 
brevis,  and  their  relation  to  the  pisiform  bone  and  hook  of  the  unciform  are 
to  be  noted. 

The  palmar  fascia  should  now  receive  careful  attention.  Its  thenar 
and  hypothenar  divisions,  which  are  thin,  are  to  be  noted,  but  attention 
is  to  be  concentrated  on  the  central  division.  Its  triangular  shape,  great 
strength,  and  the  longitudinal  direction  of  most  of  its  fibres  are  to  be  observed. 
Some  of  the  fibres,  however,  will  be  seen  to  be  disposed  transversely,  especially 
towards  the  roots  of  the  fingers.  In  this  latter  situation  it  should  be  shown 
dividing  into  four  digital  processes,  which  pass  to  become  incorporated  with 
the  sheaths  of  the  flexor  tendons  of  the  inner  four  fingers.  The  thenar  and 
hypothenar  divisions  of  the  fascia  are  removable  with  ordinary  care  in  order  to 
expose  the  muscles,  and  no  important  structure  is  in  danger.  The  central 
division,  however,  must  be  removed  with  the  greatest  care.  In  doing  so  the 
dissector  should  particularly  note  its  great  strength,  which  will  show  him 
how  it  would  resist  the  pointing  of  a  palmar  abscess,  and  the  necessity  of  early 
incision  to  give  vent  to  the  pus.  As  this  division  is  being  removed  a  deep 
lateral  expansion  is  to  be  looked  for  at  either  side  of  it,  these  expansions 
passing  to  join  the  more  deeply  placed  interosseous  fascia.  The  result 
is  that  a  great  central  fibrous  tunnel  is  formed  in  the  palm,  which  contains 
the  superficial  palmar  arch,  digital  arteries  and  nerves,  and  flexor  tendons,  all 
enclosed  in  the  great  palmar  bursa.  In  reflecting  the  digital  processes  of  the 
central  division  deep  lateral  expansions  should  be  looked  for,  which,  along 
with  them  and  the  anterior  fibrous  plates  of  the  metacarpo-phalangeal  joints, 
form  short  tunnels  for  each  pair  of  flexor  tendons. 

On  removal  of  the  central  division  of  the  palmar  fascia  the  great  palmar 
bursa  is  to  be  thoroughly  mastered.  The  superficial  palmar  arch  is  then 
to  be  dissected,  and  its  position  and  branches  are  to  be  carefully  studied. 
The  profunda  branch  is  to  be  shown  coming  off  from  the  commencement 
(inner  part)  of  the  arch,  and,  along  with  the  deep  division  of  the  ulnar  nerve, 
it  will  be  seen  to  disappear  between  the  abductor,  and  flexor  brevis,  minimi 
digiti.     Four  digital  arteries  are  to  be  followed  from  the  convexity  of  the 


THE   UPPER  LIMB  395 

arch,  the  inner  one  beinor  single  and  the  other  three  compound,  for  the  supply 
of  the  inner  three  and  a  half  fingers.  It  should  be  noted  that  the  digital 
arteries,  in  passing  to  the  fingers,  lie  over  the  interosseous  spaces  and  super- 
ficial to  the  digital  nerves.  About  the  centre  of  the  palm  the  inner  artery 
will  be  found  to  be  reinforced  by  a  communicating  branch  from  the  deeply- 
placed  innermost  palmar  interosseous,  and  the  outer  three  arteries,  close  to 
their  points  of  bifurcation,  will  be  found  to  be  joined  each  by  a  palmar  inter- 
osseous artery.  The  possible  presence  of  a  large  median  artery  joining  the 
superficial  palmar  arch  is  to  be  borne  in  mind. 

The  median  and  ulnar  nerves  are  next  to  be  dissected  in  the  palm  as  far  as 
the  roots  of  the  fingers.  The  median  nerve,  after  emerging  from  lieneath  the 
anterior  annular  ligament,  will  be  found  to  present  an  enlargement,  and  then 
to  break  up  into  outer  and  inner  divisions.  The  outer  division  is  to  be  shown 
giving  off  a  muscular  branch  which  supplies  the  abductor  poUicis,  opponens 
pollicis,  and  superficial  head  of  the  flexor  brevis  poUicis,  and  then  to  arrange 
itself  into  three  single  digital  nerves  to  both  sides  of  the  thumb  and  outer  side 
of  the  index  finger,  the  last  branch  giving  a  twig  to  the  first  or  outermost 
lumbricalis  muscle.  The  inner  division  furnishes  two  compound  digital  nerves, 
each  of  which  divides  near  the  clefts  of  the  fingers  into  two  branches  for  the 
supply  of  the  contiguous  sides  of  the  index  and  middle,  and  middle  and  ring 
fingers.  The  compound  digital  nerve  to  the  cleft  between  the  index  and 
middle  fingers  will  be  found  to  give  a  twig  to  the  second  lumbricalis,  and  that 
to  the  cleft  between  the  middle  and  ring  fingers  communicates  by  a  cross 
branch  with  the  compound  digital  branch  of  the  ulnar  nerve  to  the  cleft 
between  the  ring  and  little  fingers. 

The  ulnar  nerve  is  next  to  be  dissected  as  far  as  the  fingers.  Its  division 
into  a  sui>erficial  and  deep  branch  is  to  be  shown,  the  latter  accompanying 
the  profunda  arterv  between  the  abductor,  and  flexor  brevis,  minimi  digiti. 
The  superficial  division  will  be  found  to  supply  the  palmaris  brevis  and 
then  to  divide  into  two  digital  nerves — an  inner  single  to  the  inner  side  of 
the  little  finger,  and  an  outer  compound  for  the  supply  of  the  contiguous  sides 
of  the  httle  and  ring  fingers.  The  digital  arteries  and  nerves  are  now  to  be 
followed  along  the  sides  of  the  fingers,  where  the  nerves  will  be  seen  to  be 
superficial  to  the  arteries,  and  to  present  minute  swellings,  called  Pacinian 
bodies.  In  dissecting  the  digital  nerves  on  the  outer  side  of  the  index  finger 
and  both  sides  of  the  thumb  the  arteria  radiahs  indicis  and  the  two  branches 
of  the  arteria  princeps  pollicis  are  to  be  shown. 

The  sheaths  of  the  flexor  tendons  are  now  to  be  examined.  The  strong, 
almost  cartilaginous,  vaginal  ligaments  over  the  first  and  second  phalanges  are 
to  be  noted,  and  the  weak  membrane  opposite  the  interphalangeal  joints,  with 
its  obliquely-decussating  fibres,  is  to  be  shown.  The  sheath  being  opened,  the 
synovial  lining  is  to  be  studied,  and  the  insertions  of  the  superficial  and  deep 
flexor  tendons  are  to  be  examined.  In  connection  with  the  synovial  lining 
the  vincula  accessoria  tendinum  are  to  be  displayed,  namely,  the  Ugamenta 
longa  and  ligamenta  brevia.  The  sheath  of  the  tendon  of  the  flexor  longus 
pollicis  is  to  be  examined  in  a  similar  manner.  The  relations  of  the  synovial 
sheaths  of  the  flexor  tendons  on  the  digits  to  the  great  palmar  bursa  are  to  be 
carefully  studied. 

The  thenar  muscles  arc  now  to  be  dissected.  The  most  superficial  is 
the  abductor  pollicis,  and  beneath  this  is  the  opponens  pollicis.  The  super- 
ficial head  of  the  flexor  brevis  pollicis  lies  internal  to  the  opponens  pollicis, 
and  close  to  the  outer  side  of  the  tendon  of  the  flexor  longus  ]>ollicis,  and 
the  adductor  obliquus  pollicis  is  close  to  the  inner  side  of  that  tendon.  The 
adductor  transversus  pollicis  lies  beyond  the  obliquus,  from  which  it  is  separ- 
ated by  the  radial  artery.  The  deep  head  of  the  flexor  brevis  pollicis  is 
difficult  to  show.  It  lies  deeply,  and  arises  from  the  inner  side  of  the  base  of 
the  first  metacarpal  bone,  and  it  joins  the  adductor  obli<|uus  ])ollicis.  A  large 
bundle  of  fibres  should  be  looked  for  i)assing  from  the  adductor  obliquus 
pollicis  to  the  superficial  head  of  the  flexor  brevis  pollicis,  and  in  each  of  these 
muscles  at  its  insertion  a  small  sesamoid  bone  will  be  met  with.  The  median 
nerve  will  Ix-  found  to  supply  the  abductor,  opponens,  and  superficial  heat!  of 


396  A   MANUAL  OF  ANATOMY 

the  flexor  brevis  poUicis,  the  others  being  supplied  by  the  deep  division  of  the 
uhiar  nerve.  The  three  hypothenar  muscles  are  then  to  be  dissected.  The 
profunda  branch  of  the  ulnar  artery  and  deep  division  of  the  ulnar  nerve  pass 
between  the  abductor,  and  flexor  brevis,  minimi  digiti,  and  then  pierce  the 
opponens  minimi  digiti,  these  three  muscles  being  suppUed  by  the  deep  division 
of  the  nerve. 

The  anterior  annular  ligament  is  now  to  be  dissected,  the  structures  related 
to  it  superficially  are  to  be  revised,  and  the  ligament  is  then  to  be  divided 
in  order  to  examine  the  contents  of  the  fibro-osseous  canal  which  it  forms 
with  the  front  of  the  carpus.  The  great  palmar  bursa  is  to  be  carefully 
noted  passing  upwards  beneath  it,  and  descending  will  be  found  the  super- 
ficial and  deep  flexor  tendons,  tendon  of  the  flexor  longus  pollicis,  and 
median  nerve.  Lying  in  a  special  compartment  of  the  ligament,  at  its  outer 
part,  will  be  found  the  tendon  of  the  flexor  carpi  radialis,  as  it  traverses  the 
groove  on  the  palmar  aspect  of  the  trapezium.  The  superficial  flexor 
tendons  may  then  be  divided  in  the  palm,  to  enable  the  deep  flexor  tendons 
to  be  raised  and  placed  over  the  handle  of  a  scalpel.  The  lumbricales, 
arising  from  these  deep  tendons,  are  then  to  be  dissected,  and  their  nerve- 
supply  noted,  namely,  the  deep  division  of  the  ulnar  for  the  inner  two,  and  the 
median  for  the  outer  two.  The  deep  flexor  tendons  are  to  be  cut  and  turned 
downwards  with  the  lumbricales,  in  order  to  expose  the  radial  artery  in  the 
palm,  where  it  forms  the  deep  palmar  arch,  which  is  completed  by  the  profunda 
branch  of  the  ulnar.  The  arteria  princeps  pollicis  and  arteria  radialis  indicis 
are  to  be  shown  arising  from  the  radial  as  it  passes  to  the  front  of  the  hand, 
and  the  palmar  interosseous,  recurrent,  and  superior  perforating  branches  of 
the  deep  palmar  arch  are  to  be  dissected.  The  deep  division  of  the  ulnar 
nerve  is  next  to  be  followed  out,  and  its  extensive  muscular  distribution  is  to 
be  carefully  studied. 

Back  of  the  Forearm  and  Hand. — The  skin  having  been  carefully  removed, 
the  dorsal  venous  arch,  with  its  tributaries,  is  to  be  shown  on  the  back  of  the 
hand,  and  the  radial  nerve  and  the  dorsal  branch  of  the  ulnar  nerve  are  to  be 
followed  to  their  digital  distributions.  In  removing  the  deep  fascia  froin  the 
back  of  the  forearm,  care  should  be  taken  to  leave  intact  the  thickened 
portion  of  it  on  the  back  of  the  wrist  which  forms  the  posterior  annular  liga- 
ment. The  muscles  on  the  outer  side  of  the  forearm  are  to  be  dissected  first, 
in  the  following  order  :  brachio-radialis,  extensor  carpi  radialis  longior, 
and  extensor  carpi  radialis  brevior.  The  superficial  layer  of  muscles  on 
the  back  of  the  forearm  are  then  to  be  dissected  as  follows  :  extensor  com- 
munis digitorum,  extensor  minimi  digiti,  extensor  carpi  ulnaris,  and  anconeus. 
Without  disturbing  meanwhile  the  posterior  annular  ligament,  the  extensor 
tendons  are  to  be  followed  over  the  back  of  the  hand  to  their  insertions.  In 
doing  this,  the  thin,  deep  fascia  on  the  dorsum,  continuous  above  with  the 
posterior  annular  ligament,  is  to  be  noted,  and  care  is  to  be  taken  to  preserve 
the  dorsal  arteries.  The  dissector  will  find  the  tendon  of  the  extensor  indicis 
lying  inside  the  common  extensor  tendon  to  the  index  finger,  and  the  tendon 
of  the  extensor  minimi  digiti  will  usually  be  found  to  be  double.  The  flat 
bands  which  connect  the  ring-finger  tendon  with  that  on  either  side  of  it 
are  to  be  shown,  as  well  as  a  band  connecting  the  middle-finger  tendon 
with  the  common  extensor  tendon  to  the  index  finger.  The  expansions  of 
the  common  extensor  tendons  over  the  backs  of  the  first  phalanges  are 
to  be  shown,  and  it  will  be  seen  that  these  receive  the  insertions  of  the 
lumbricales  and  interossei.  The  mode  of  insertion  of  the  extensor  tendons 
is  then  to  be  examined. 

Returning  to  the  back  of  the  forearm,  the  superficial  muscles  are  to  be  held 
well  aside,  and  the  posterior  interosseous  nerve  and  artery  dissected.  The 
nerve,  having  wound  round  the  outer  side  of  the  radius  in  the  supinator 
radii  brevis,  will  be  found  emerging  from  that  muscle  behind  near  its  lower 
border,  and  a  little  below  this  the  artery  meets  it,  after  having  passed  back- 
wards between  the  radius  and  ulna.  The  nerve  is  now  to  be  followed  down- 
wards between  the  superficial  and  deep  muscles,  and  then  beneath  the  extensor 
longus  pollicis,  but  no  lower  in  the  meantime,  and  its  muscular  distribution 


THE  UPPER  LIMB  397 

is  to  be  noted.  The  posterior  interosseous  artery  will  be  found  to  give  off 
its  posterior  interosseous  recurrent  branch  as  soon  as  it  reaches  the  back  of 
the  forearm.  This  branch  is  to  be  followed  upwards  beneath  the  anconeus 
to  the  back  of  the  external  epicondyle,  where  it  anastomoses  with  the  posterior 
terminal  branch  of  the  superior  profunda.  If  well  injected,  it  will  be  found 
to  give  branches  to  the  back  of  the  olecranon  process,  which  anastomose 
with  branches  of  the  posterior  ulnar  recurrent  to  form  the  olecranon  rete. 
The  posterior  interosseous  artery,  as  it  descends  with  the  nerve,  gets  very 
small,  and  usually  ceases  before  reacliing  the  wrist,  where  its  place  is  taken 
by  the  posterior  branch  of  the  anterior  interosseous,  with  which  it  anas- 
tomoses. 

The  muscles  of  the  deep  layer  are  then  to  be  dissected  in  the  following  order  : 
supinator  radii  brevis,  extensor  ossis  metacarpi  pollicis,  extensor  brevis 
poUicis,  extensor  longus  pollicis,  and  extensor  indicis.  The  posterior  annular 
ligament  is  next  to  be  carefully  dissected,  and,  by  opening  it  up,  the  fibro- 
osseous  canals  which  it  forms  with  the  grooves  on  the  lower  ends  of  the  radius 
and  ulna  are  to  be  studied.  The  localization  of  the  various  tendons  in  these 
canals  is  to  be  mastered,  and  careful  attention  is  to  be  given  to  their  synovial 
sheaths.  The  mode  of  termination  of  the  posterior  interosseous  nerve  is  also 
to  be  shown  at  this  stage.  It  will  be  found  to  end  beneath  the  tendons  of 
the  extensor  communis  digitorum  in  a  gangliform  enlargement,  from  which 
articular  twigs  are  given  off  to  the  adjacent  joints.  The  radial  artery  on 
the  back  of  the  wrist  and  its  branches  are  next  to  be  dissected,  and  the 
dissector  is  to  note  that  the  artery,  just  before  it  dips  between  the  two  heads 
of  the  abductor  indicis,  is  crossed  by  the  tendon  of  the  extensor  longus  pollicis. 
In  connection  with  the  posterior  radial  carpal  artery,  the  posterior  ulnar  carpal 
is  to  be  shown,  as  well  as  the  posterior  carpal  arch,  beneath  the  extensor 
tendons.  The  inner  two  dorsal  interosseous  arteries  are  to  be  shown  arising 
from  this  arch,  and  the}^  are  to  be  followed  downwards  over  the  inner  two 
interosseous  spaces  to  near  the  clefts  between  the  middle  and  ring,  and  ring 
and  little  fingers,  where  each  divides  into  two  dorsal  collateral  digital  branches. 
The  inner  of  the  two  arteries  may  give  a  branch  to  the  inner  side  of  the  little 
finger,  or  this  may  arise  from  the  posterior  ulnar  carpal.  The  first  dorsal 
interosseous  artery  is  to  be  followed  from  the  radial  over  the  second  inter- 
osseous space  to  near  the  cleft  between  the  index  and  middle  fingers,  where  it 
also  divides  into  two  dorsal  collateral  digital  arteries.  The  superior  perforating 
branches  of  the  deep  palmar  arch  are  to  be  shown  after  they  have  pierced  the 
upper  ends  of  the  inner  three  interosseous  spaces  between  the  two  heads  of 
the  dorsal  interosseous  muscles,  where  each  joins  a  dorsal  interosseous  artery. 
Each  of  these  dorsal  interosseous  arteries  may  give  off  an  inferior  perforating 
branch,  before  it  bifurcates,  to  join  a  digital  artery  from  the  superficial  palmar 
arch.  The  arteria  dorsalis  pollicis  is  next  to  be  shown,  and  it  will  be  found  to 
divide  into  two  branches  (which  sometimes  arise  separately)  for  the  sides  of  the 
thumb.  Lastly,  the  arteria  dorsalis  indicis,  which  arises  from  the  radial  just 
before  it  leaves  the  back  of  the  wrist,  is  to  be  followed  along  the  outer  side 
of  the  second  metacarpal  bone  to  the  outer  side  of  the  index  finger. 

The  interosseous  muscles  are  next  to  be  dissected.  In  cleaning  the  palmar 
interossei  the  interosseous  fascia  is  to  be  noted,  and  its  relation  to  the  central 
division  of  the  palmar  fascia  is  to  be  revised.  In  cleaning  the  dorsal  inter- 
ossei a  thin,  deep  dorsal  fascia  will  be  removed.  It  will  also  be  necessary  to 
dissect  the  transverse  metacarpal  (deep  transverse)  ligament,  which  stretches 
across  the  heads  of  the  four  inner  metacarpal  bones  on  tlieir  palmar  aspects. 
This  having  been  cut,  the  muscles  are  now  to  be  fully  dissected,  and  their 
nerve-sui)fjly  and  actions  carefully  studied. 

Elbow-Joint. — Tlie  muscles  related  to  this  joint  are  to  be  replaced,  and  tlieir 
relation  to  it  noted.  The  adjacent  nerves  arc  also  to  be  observed,  and  the 
anastomoses  of  arteries  around  the  joint  are  to  be  thorougiily  mastered.  The 
ligaments  wliicli  compose  the  cajisule,  namely,  anterior,  ])osterior,  external 
lateral,  anrl  internal  lateral,  are  to  l)e  dissected,  and  the  joint  is  tlien  to  be 
opened.  The  articular  surfaces  are  to  be  examined,  the  pads  of  fat  noted, 
and  the  synovial  membrane  and  movements  studied. 


398  A   MANUAL  OF  ANATOMY 

Wrist-Joint. — This  joint  is  to  be  studied  in  the  same  way  as  the  elbow-joint. 

Radio-ulnar  Joints. — The  superior  radio-ulnar  joint  has  only  the  orbicular 
or  annular  ligament,  and  its  synovial  membrane  is  continuous  with  that  of  the 
elbow-joint.  The  chief  bond  of  union  at  the  inferior  radio-ulnar  joint  is  the 
triangular  fibro-cartilage,  which  is  to  be  carefully  examined,  along  with  the 
synovial  membrane,  which  is  called  the  membrana  sacciformis.  As  regards 
the  intermediate  connection  between  the  radius  and  ulna,  the  interosseous 
membrane  is  to  be  dissected,  and  its  anterior  and  posterior  relations  studied. 
The  opening  in  it  near  its  lower  part  for  the  posterior  branch  of  the  anterior 
interosseous  artery  is  to  be  shown.  The  obUque  ligament  at  the  upper  end 
is  to  be  examined,  and  between  it  and  the  upper  border  of  the  interosseous 
membrane  will  be  seen  the  interval  for  the  passage  of  the  posterior  interosseous 
vessels.  The  movements  of  pronation  and  supination  are  to  receive  close 
attention,  and  the  dissector  is  to  make  himself  thoroughly  familiar  with  the 
muscles  concerned  in  these  important  movements. 

Carpal  Joints. — The  transverse  carpal  joint  is  to  be  dissected  first,  and  the 
ligaments  and  movements  are  to  be  studied.  The  pisiform  joint  is  next  to  be 
examined,  and  its  capsular  Ugament  shown.  The  dorsal,  palmar,  and  inter- 
osseous ligaments  of  the  other  three  bones  of  the  first  row  are  next  to  be 
examined,  followed  by  those  of  the  second  row.  The  carpo-metacarpal  joints 
are  to  be  studied,  and  special  attention  should  be  directed  to  the  joint  between 
the  trapezium  and  first  metacarpal  bone.  The  intermetacarpal  (basal)  joints 
follow  next.  The  deep  transverse  ligament  which  connects  the  palmar  aspects 
of  the  heads  of  the  four  inner  metacarpal  bones  has  been  already  dissected. 
The  metacarpo-phalangeal  joints,  followed  by  the  interphalangeal,  are  next  to 
be  dissected.  The  strong  anterior  fibrous  plate  is  to  be  noted,  and  the  absence 
of  a  dorsal  ligament,  its  place  being  taken  by  the  extensor  tendon.  In  the 
metacarpo-phalangeal  joint  of  the  thumb  no  anterior  fibrous  plate  will  be  found, 
its  place  being  taken  by  two  sesamoid  bones.  Special  attention  is  to  be  given 
to  the  arrangement  of  the  synovial  membranes,  from  the  inferior  radio-ulnar 
joint  above,  with  its  membrana  sacciformis,  to  the  intermetacarpal  (basal) 
joints  below.  The  number  of  these  synovial  membranes  and  the  complexity 
of  that  of  the  carpus  are  to  be  noted. 


THE    LOWER    LIMB 


THE  GLUTEAL  REGION. 


Landmarks. — The  crest  of  the  ihum  is  ahnost  entirely  obscured  by 
the  prominence  of  the  abdominal  muscles  above  it  and  the  gluteus 
medius  below  it,  so  that  as  a  rule  its  position  is  indicated  by  a 
groove.  This  groove  conducts  the  finger  to  the  posterior  superior 
iliac  spine,  which  is  on  a  level  with  the  second  sacral  spine  and  the 
centre  of  the  sacro-iliac  synchondrosis.  The  spinous  processes  of 
the  sacral  vertebrae,  usually  four  in  number,  may  be  distinguished 
as  separate  projections,  or  they  may  be  fused  into  one  median  ridge. 
The  fifth  sacral  spine  being  undeveloped,  no  median  projection  can 
be  felt,  but  at  either  side  of  the  middle  line  the  sacral  cornua  may 
be  made  out.  The  coccyx  is  felt  in  the  natal  cleft  between  the 
buttocks.  The  tuber  ischii  is  obscured  by  the  lower  border  of  the 
gluteus  maximus  when  the  hip- joint  is  extended,  but,  when  that 
joint  is  flexed,  the  prominence  is  easily  made  out.  The  great 
trochanter  is  felt  at  the  lower  and  outer  part  of  the  gluteal  region, 
and  behind  it  there  is  a  natural  depression.  The  prominence  of 
the  natis  or  buttock  is  formed  by  the  gluteus  maximus,  covered 
by  a  large  amount  of  adipose  tissue.  The  fold  of  the  natis  is 
produced  by  a  fold  of  the  skin  and  fascia,  and  is  very  perceptible 
when  the  hip-joint  is  extended.  It  takes  the  form  of  a  transverse 
furrow,  which  commences  internally  a  little  below  the  lower  border 
of  the  gluteus  maximus,  and  terminates  externally  on  the  surface 
of  that  muscle,  having  crossed  its  lower  border.  The  fold  is  hori- 
zontal in  direction,  whilst  the  lower  border  of  the  gluteus  maximus 
is  oblique.  It  is  possible  to  feel  the  great  sciatic  nerve  in  this  fold, 
but  that  nerve  lies  deejjly  at  a  point  very  nearly  midway  between 
the  great  trochanter  and  tuber  ischii,  being  rather  nearer  the  latter 
than  the  former. 

Cutaneous  Nerves. — These  are  met  with  in  the  following  situations  : 
(i)  line  (){  origin  (jf  gluteus  maximus  ;  (2)  iliac  crest  ;  (3)  outer  and 
lower  j)art  of  gluteus  maximus  ;  and  (4)  lower  border  of  gluteus 
maximus. 

I.  Line  of  Origin  of  Gluteus  Maximus.  Tlic  <  utaneous  nerves  met 
with  in  tiiis  situation  arc  divisible  into  three  sets. 

i'j'j 


400  A    MANUAL  OF  ANATOMY 

(a)  Two  or  three  twigs  from  the  external  branches  of  the  posterior 
primary  divisions  of  the  first  three  sacral  nerves.  These  external 
branches  form  two  sets  of  loops,  one  set  being  situated  deeply  on 
the  back  of  the  sacrum,  and  the  other  set  more  superficially  on  the 
posterior  surface  of  the  great  sacro-sciatic  ligament.  It  is  from  this 
latter  set  of  loops  that  the  two  or  three  cutaneous  twigs  are  derived, 
and  their  direction  is  chiefly  outwards. 

{b)  One  or  two  twigs  from  the  undivided  posterior  primary  divisions 
of  the  last  two  sacral  nerves  and  the  coccygeal  nerve.  These 
divisions  form  a  loop  on  the  back  of  the  sacrum,  from  which  the 
cutaneous  twigs  are  derived,  their  distribution  being  confined  to  the 
coccygeal  integument. 

(c)  Twigs  from  the  so-called  coccygeal  plexus,  which  is  situated 
on  the  pelvic  surface  of  the  coccygeus  muscle.  These  twigs  pierce 
that  muscle  and  the  small  sacro-sciatic  ligament,  as  well  as  the 
gluteus  maximus,  and  are  distributed  to  the  coccygeal  integument. 

2.  Iliac  Crest. — The  cutaneous  nerves  in  this  situation  from  behind 
forwards  are  also  divisible  into  three  sets. 

(a)  Three  offsets  from  the  external  branches  of  the  posterior 
primary  divisions  of  the  first  three  lumbar  nerves,  which  descend 
over  the  iliac  crest,  in  front  of  the  outer  border  of  the  erector  spinse 
muscle. 

{b)  Iliac  branch  of  the  ilio-hypogastric  nerve,  which  crosses  the 
iliac  crest  at  the  junction  of  the  middle  and  anterior  thirds. 

(c)  Undivided  lateral  cutaneous  or  iliac  branch  of  the  anterior 
primary  division  of  the  twelfth  thoracic  (subcostal)  nerve.  This  is 
a  large  and  long  nerve  which  descends  over  the  anterior  part  of  the 
iliac  crest,  i  inch  behind  the  anterior  superior  iliac  spine,  and  is 
distributed  to  the  integument  of  the  anterior  part  of  the  gluteal 
region  as  low  as  the  great  trochanter. 

3.  Outer  and  Lower  Part  of  Gluteus  Maximus. — The  cutaneous 
nerves  appearing  in  this  situation  are  branches  of  the  posterior 
division  of  the  external  cutaneous  nerve,  which  is  derived  from  the 
lumbar  plexus. 

4.  Lower  Border  of  Gluteus  Maximus. — The  cutaneous  nerves  met 
with  in  this  locality  are  as  follows  : 

{a)  Three  or  four  recurrent  branches  from  the  small  sciatic  nerve, 
which  supply  the  integument  over  the  lower  and  outer  part  of  the 
gluteus  maximus. 

(&)  Perforating  cutaneous  branch  of  the  sacral  plexus,  more 
particularly  from  the  back  of  the  second  and  third  sacral  nerves, 
which  supplies  the  integument  over  the  lower  and  inner  part  of  the 
gluteus  maximus. 

Fasciae. — The  superficial  fascia  is  very  thick,  and  loaded  with 
adipose  tissue.  It  is  continuous  over  the  iliac  crest  with  the  super- 
ficial fascia  of  the  back  of  the  trunk,  and  it  contributes  to  the 
prominence  of  the  natal  region.  Between  the  iliac  crest  and  the 
upper  border  of  the  gluteus  maximus  there  is  a  considerable 
accession  of  adipose  tissue  to  the  deep  surface  of  the  superficial 


THE  LOWER  LIMB  401 

fascia,  and  so  the  depression  in  that  region  is  filled  up.  The  deep 
fascia  forms  a  part  of  the  fascia  lata.  Over  the  fleshy  part  of 
the  gluteus  maximus  it  is  thin,  but,  at  the  insertion  of  the  muscle 
and  over  the  anterior  two- thirds  of  the  gluteus  medius,  it  is  dense. 
In  these  latter  situations  it  gives  insertion  to  a  considerable  part 
of  the  gluteus  maximus,  and  origin  to  the  superficial  fibres  of  the 
gluteus  medius  in  its  anterior  two-thirds.  In  passing  from  the 
gluteus  medius  on  to  the  gluteus  maximus  it  straps  down  the  upper 
border  of  the  latter  muscle. 

Muscles.  Gluteus  Maximus — Origin. — (i)  The  posterior  2  inches 
of  the  outer  lip  of  the  iliac  crest  ;  (2)  the  upper  part  of  the  rough 
surface  on  the  dorsum  ilii  between  this  part  of  the  crest  and  the 
superior  gluteal  line  ;  (3)  the  posterior  lamina  of  the  lumbar 
aponeurosis  ;  (4)  the  lateral  part  of  the  back  of  the  fourth  and 
fifth  sacral  vertebrae  ;  (5)  the  back  of  the  upper  three  coccygeal 
vertebrae  close  to  the  lateral  border  ;  and  (6)  the  superficial  surface 
of  the  great  sacro-sciatic  ligament. 

Insertion. — (i)  Rather  more  than  the  upper  half  of  the  muscle  is 
inserted  between  two  laminae  of  the  fascia  lata  on  the  upper  and 
outer  part  of  the  thigh  ;  (2)  the  superficial  fibres  of  rather  less  than 
the  lower  half  are  also  inserted  into  the  fascia  lata,  but  the  deep 
fibres  of  this  portion  are  inserted  into  the  gluteal  ridge  of  the  femur. 
The  part  of  the  fascia  lata  which  gives  insertion  to  the  gluteus 
maximus  is  known  as  the  ilio-tibial  band. 

Nerve-supply. — The  inferior  gluteal  nerve  from  the  sacral  plexus, 
which  enters  the  muscle  on  its  deep  or  anterior  surface  in  its  lower 
third. 

The  direction  of  the  coarse  fasciculi  of  the  muscle  is  downwards 
and  outwards. 

Action. — Acting  from  its  origin  the  muscle  extends  the  thigh  upon 
the  pelvis,  as  in  rising  from  the  sitting  posture,  or  ascending  a  stair. 
The  upper  part,  acting  alone,  would  abduct  the  thigh,  and  the  lower 
part  would  adduct  it  and  rotate  it  outwards.  The  muscle  also  takes 
part  in  the  completion  of  extension  of  the  knee-joint,  and  in  the 
maintenance  of  extension,  as  in  standing,  through  means  of  the 
ilio-tibial  band  of  the  fascia  lata.  Acting  from  its  insertion  the 
muscle  extends  the  pelvis  upon  the  thigh,  as  in  raising  the  trunk 
from  the  stooping  posture. 

The  gluteus  maximus,  which  is  quadrilateral,  has  a  short  upper 
border  which  is  bound  down  to  the  gluteus  medius  by  the  fascia 
lata,  and  a  long  lower  border  which  is  free. 

Deep  Relations. — These,  from  above  downwards,  are  as  follows  : 
the  posterior  fleshy  third  of  gluteus  medius  ;  superficial  division 
of  gluteal  artery  ;  extrapelvic  part  of  pyriformis  ;  great  and  small 
sciatic  nerves ;  inferior  gluteal  nerve  ;  sciatic  and  internal  pudic 
arteries  ;  pudic  nerve  ;  nerve  to  obturator  internus,  supplying  a 
branch  to  gemellus  sujjerior  ;  common  nerve  to  gemellus  inferior  and 
quadratus  femoris  ;  gemellus  su])erior  ;  extraj)elvic  part  of  obturator 
internus ;  gemellus  inferior  ;  quadratus  femoris  ;  crucial  anastomosis 

26 


402 


A   MANUAL  OF  ANATOMY 


of  arteries ;  upper  horizontal  part  of  adductor  magnus  ;  origins  of 
hamstring  muscles  from  tuber  ischii ;  portion  of  vastus  externus, 
just  below  the  great  trochanter  ;  and  great  sacro-sciatic  ligament^ 


Gluteus  Medius_, 


Gluteus  Maximus 


Biceps 1 

Semitendinosus 

Semimembrano'sus 
Crureus 

Gracilis 

Internal  Popliteal  Nerve 
Sartorius  _  . 


Gastrocnemius 


Ilio-hypogastric  Nerve 
Lateral  Cutaneous  of 
1 2th  Thoracic  Nerve 
Posterior  Divisions  of 
first  three  Lumbar 
Nerves 

Posterior  Divisions  of 
Sacral  Nerves 

Post.  Div.  of  Cocc.  N. 

Perforating  Cutan.  N. 
.Gluteal  Branches  of 
Small  Sciatic  Nerve 
Post.  Branch  of  Ext. 
Cutaneous  Nerve 


Small  Sciatic  Nerve 

(Outline) 
Femoral  Branches  of 
Small  Sciatic  Nerve 


Ext.  Cutaneous  N. 
(Anterior  Branch) 


Small  Sciatic  Nerve 


Posterior  Branch  of  Int. 

Cutaneous  Nerve 
Lateral  Cutaneous  of 
External  Popliteal 
Nerve 


Ramus  Commun.  Fib. 
Ramus  Commun.  Tib. 


Ext.  Saphenous  Nerve 

Branches  of  Internal 
Saphenous  Nerve 


Soleus-j 

Flexor  Longus 
Digitorum.,. 

Peroneus  Longus  .. 

Tendo  Achillis— 

Tibialis  Posticus.... 
Plantaris 


Fig    215. — Muscles  and  Cutaneous  Nerves  of  the  Lower  Limb 
(Posterior  .\spect). 

pierced  by  the  coccygeal  branch  of  the  sciatic  artery,  the  sacral 
branch  of  the  internal  pudic  artery,  and  the  perforating  cutaneous 
branch  of  the  sacral  plexus. 


THE  LOWER  LIMB  403 

Three  synovial  bursae  are  found  underneath  the  muscle.  One, 
which  is  single,  is  situated  between  the  lower  border  of  the  muscle 
and  the  tuber  ischii.  Its  importance  consists  in  the  fact  that  it  is 
concerned  in  the  condition  known  as  'lighterman's  bottom.'  A 
second  lies  between  the  muscle  and  the  great  trochanter,  this 
one  being  multilocular.  The  third  is  found  between  the  muscle 
and  the  upper  part  of  the  vastus  externus,  just  below  the  great 
trochanter. 

Gluteus  Medius — Origin. — (i)  The  dorsum  ilii  between  the  crest, 
superior  gluteal  line,  and  middle  gluteal  line  :  and  (2)  the  fascia  lata 
covering  the  anterior  two-thirds  of  the  muscle. 

Insertion. — The  oblique  impression  on  the  outer  surface  of  the 
great  trochanter,  extending  from  the  postero-superior  angle  down- 
wards and  forwards  to  the  antero-inferior  angle. 

Nerve-supply. — The  superior  gluteal  nerve. 

The  direction  of  the  anterior  fibres  of  the  muscle  is  downwards 
and  slightly  backwards,  and  of  the  posterior  fibres  downwards  and 
forwards.  The  fibres  of  the  muscle  converge  from  their  origin  to 
the  fan-shaped  tendon  of  insertion,  and  they  correspond  in  direction 
with  those  of  the  gluteus  minimus. 

Action. — Acting  from  its  origin  the  muscle  abducts  the  thigh. 
The  anterior  fibres  also  act  as  an  internal  rotator,  and  the  posterior 
fibres  as  an  external  rotator,  of  the  thigh.  Acting  from  its  insertion 
it  balances  the  pelvis  upon  the  thigh,  as  in  standing  upon  one  leg, 
and  it  is  also  a  lateral  flexor  of  the  pelvis. 

The  gluteus  medius  is  triangular.  The  posterior  fleshy  third  is 
covered  by  the  gluteus  maximus,  and  the  anterior  two-thirds  by 
the  fascia  lata.  The  muscle  covers  the  gluteus  minimus  except 
posteriorly,  the  deep  division  of  gluteal  artery,  and  the  superior 
gluteal  nerve,  and  a  synovial  bursa  intervenes  between  it  and  the 
upper  part  of  the  great  trochanter. 

Gluteus  Minimus — Origin. — The  dorsum  ilii  between  the  middle 
and  inferior  gluteal  lines. 

Insertion. — The  lower  part  of  the  anterior  surface  of  the  great 
trochanter. 

Nerve -supply.— The  lower  division  of  the  superior  gluteal 
nerve. 

The  fibres  of  the  muscle  correspond  in  direction,  for  the  most 
part,  with  those  of  the  gluteus  medius. 

Action. — Acting  from  its  origin  the  muscle  is  an  abductor 
and  internal  rotator  of  the  thigh.  Acting  from  its  insertion  it 
balances  the  pelvis  upon  the  thigh,  and  is  a  lateral  flexor  of  the 
pelvis. 

The  gluteus  minimus  is  fan-shaped,  and  the  tendon  of  insertion 
spreads  out  into  an  aponeurotic  expansion  over  its  lower  part. 
It  is  covered  by  the  gluteus  medius  except  at  the  posterior  part, 
where  the  pyriformis  rests  upon  it.  Its  deep  surface  is  related  to 
the  capsular  ligament  of  the  hip-joint  and  the  posterior  or  reflected 
head  of  the  rectus  femoris.     The  tendon  of  insertion  of  the  muscle 

26 — 2 


404  A  MANUAL  OF  ANATOMY 

is  separated  from  the  great  trochanter  by  a  synovial  bursa,  and  is 
connected  with  the  upper  part  of  the  capsular  ligament  of  the  hip- 
joint  by  a  strong  arched  band  of  fibres. 

The  anterior  portion  of  the  gluteus  minimus  is  sometimes 
detached  from  the  rest  of  the  muscle,  and,  when  this  occurs, 
the  separated  part  represents  the  gluteus  quartus  or  musculus 
scansorius  (climbing  muscle)  of  certain  animals. 

Pyriformis — Origin. — (i)  By  three  fleshy  slips  from  the  anterior 
surfaces  of  the  second,  third,  and  fourth  sacral  vertebrae,  which 
are  interposed  between,  and  lie  external  to,  the  adjacent  anterior 
sacral  foramina  ;  (2)  the  deep  surface  of  the  great  sacro-sciatic  liga- 
ment; and  (3)  the  posterior  border  of  the  ilium  immediately  below 
the  posterior  inferior  iliac  spine. 

Insertion. — ^The  upper  border  of  the  great  trochanter  near  its 
centre. 

Nerve-supply. — ^Two  branches  from  the  sacral  plexus,  which  enter 
the  intrapelvic  part  of  the  muscle.  The  branches  come  from  the 
dorsal  divisions  of  the  first  and  second  sacral  nerves. 

Action. — External  rotator  of  the  thigh. 

The  pyriformis,  in  emerging  from  the  pelvis  through  the  great 
sacro-sciatic  foramen,  divides  that  foramen  into  a  small  upper  and 
a  large  lower  compartment.  Through  the  upper  compartment  the 
gluteal  vessels  and  superior  gluteal  nerve  pass.  Through  the  lower 
compartment  the  following  structures  are  transmitted  :  the  sciatic 
and  internal  pudic  vessels,  great  and  small  sciatic  nerves,  inferior 
gluteal  nerve,  pudic  nerve,  nerve  to  obturator  internus,  and  common 
nerve  to  gemellus  inferior  and  quadratus  femoris.  The  extra- 
pelvic  part  of  the  pyriformis  is  sometimes  pierced  by  the  external 
popliteal  nerve. 

Gemellus  Superior — Origin. — The  lower  border  and  adjacent 
portion  of  the  external  surface  of  the  spine  of  the  ischium. 

Insertion. — The  upper  border  of  the  tendon  of  the  obturator 
internus. 

Nerve-supply. — Branch  from  the  nerve  to  the  obturator  internus, 
which  enters  the  muscle  on  its  anterior  or  deep  surface  near  the 
upper  border,  close  to  the  origin. 

The  gemellus  superior  is  sometimes  absent. 

Obturator  Internus — Origin. — (i)  The  internal  surface  of  the 
obturator  membrane  ;  (2)  the  posterior  surface  of  the  body  of  the 
OS  pubis,  descending  pubic  ramus,  and  ascending  ramus  of  the 
ischium  ;  (3)  the  inclined  plane  of  the  ischium,  extending  as  far 
back  as  the  great  sacro-sciatic  foramen,  and  nearly  as  high  as  the 
iliac  portion  of  the  ilio-pectineal  line  ;  and  (4)  the  parietal  pelvic 
fascia  covering  the  muscle. 

Insertion. — The  inner  surface  of  the  great  trochanter,  above  and 
in  front  of  the  digital  fossa. 

Nerve-supply. — The  nerve  to  the  obturator  internus  from  the 
sacral  plexus. 

Action. — External  rotator  of  the  thigh. 


THE  LOWER  LIMB  405 

The  intrapelvic  and  extrapelvic  parts  of  the  muscle  form  very 
nearly  a  right  angle  with  each  other.  It  emerges  from  the  pelvis 
through  the  small  sacro-sciatic  foramen,  and  the  deep  surface  of 
its  tendon  is  here  broken  up  into  from  three  to  five  columns, 
separated  from  each  other  by  grooves.  The  small  sciatic  notch 
is  covered  by  cartilage,  which  presents  as  many  grooves  as  there 
are  columns  on  the  deep  surface  of  the  tendon,  these  grooves  being 
separated  by  slight  ridges.  The  grooves  lodge  the  columns  of  the 
tendon,  and  the  ridges  are  received  into  the  grooves  between  the 
tendinous  columns.  A  bursa  intervenes  between  the  tendon  and 
the  cartilage  covering  the  notch. 

Gemellus  Inferior — Origin. — The  upper  part  of  the  tuber  ischii, 
and  the  lower  margin  of  the  small  sciatic  notch. 

Insertion. — -The  lower  border  of  the  tendon  of  the  obturator 
internus. 

Nerve-supply. — Branch  from  the  nerve  to  the  quadratus  femoris, 
which  enters  the  muscle  on  its  deep  or  anterioi  surface  near  the 
upper  border,  close  to  the  origin. 

The  gemelli  muscles  are  merely  extrapelvic  origins  of  the  obtu- 
rator internus,  of  which  they  form  accessory  parts.  As  they  take 
insertion  into  the  upper  and  lower  borders  of  the  obturator  tendon 
they  are  folded  over  it,  so  as  to  overlap  and  partially  conceal  the 
tendon  on  its  superficial  aspect.  They  are  auxiliary  to  the  obturator 
internus  in  action. 

Small  Sacro-sciatic  Foramen. — The  structures  which  pass  through  this 
foramen  are  as  follows  :  (i)  obturator  internus  ;  (2)  nerve  to  the  obturator 
internus  ;  (3)  pudic  nerve  ;  and  (4)  internal  pudic  artery  with  its  venas  comites. 

Quadratus  Femoris — Origin. — The  outer  border  of  the  tuber  ischii. 

Insertion. — The  linea  quadrati  of  the  femur,  extending  as  low 
as  the  small  trochanter. 

Nerve-supply. — The  nerve  to  the  quadratus  femoris  from  the 
sacral  plexus,  which  enters  the  muscle  on  its  deep  or  anterior 
surface  near  the  upper  border,  close  to  the  origin. 

Action. — External  rotator  of  the  thigh. 

The  muscle  conceals  part  of  the  obturator  externus  and  the 
small  trochanter  of  the  femur,  from  which  latter  it  is  separated  by 
a  small  bursa.  When  the  gemellus  inferior  and  quadratus  femoris 
are  separated,  part  of  the  obturator  externus  comes  into  view. 
Between  the  lower  border  of  the  muscle  and  the  upper  border 
of  the  adductor  magnus  the  transverse  branch  of  the  internal 
circumflex  artery  appears,  which  here  takes  part  in  the  crucial 
anastomosis.  When  the  lower  border  of  the  muscle  is  raised,  the 
small  trochanter  comes  into  view  with  the  tendon  of  insertion  of 
the  ilio-psoas. 

Arteries. — The  chief  arteries  of  the  gluteal  region  are  the  gluteal, 
sciatic,  and  internal  j)udic. 

Gluteal  Artery. — This  vessel  arises  from  the  posterior  division 
of  the  internal  iliac  artery.     Piercing  the  parietal  pelvic  fascia,  it 


4o6 


A  MANUAL  OF  ANATOMY 


Gluteus  Maximus 

(origin)  .w^y 

Gluteal  Artery l//^ 

Superior  Gluteal  Nerve Ji 

Pyriformis 

Internal  Pudic  Artery 
and  Pudic  Nerve 
Nerve  to  Obturator 

Internus 
Great  Sacro-sciatic- 
Ligament 
Sciatic  Arter)' L 


Great  Sciatic  Nerve  and = 

Comes  Nervi  Ischiad.  I 

Long  Pudendal  Nerve._.  'I 

Hamstring  Muscles__ 
(origin) 

Adductor  Magnus 
(Ischio-pubic  portion) 


Part  of  Adductor  Magnus 
from  Tuber  Ischii  to 
Adductor  Tubercle 


Lower  Part  of 
Great  Sciatic  Nerve 

Int.  Popliteal  Nerve 

Popliteal  Vein 

Popliteal  Artery. 

Femoral  Opening, 

Tendon  of 
Adductor  Magnus. _. 


Gluteus  Medius 
(reflected) 

Lower  Branch  of  Deep 
Div.  of  Gluteal  Artery 


_  Gluteus  Maximus 
f/  /^  (insertion) 

—  Obturator  Internus 
and  Gemelli 

_  Quadratus  Femoris 


Small  Sciatic  Nerve 
Crucial  Anastomosis 


First  Perforating  Artery 
Vastus  Externus 


Second  Perforating  Artery 

Third  Perforating  Artery 

Fourth  Perforating  Artery 

Femoral  Head  of  Biceps 

External  Popliteal  Nerve 


Tendon  of  Insertion  of  Biceps 


Fig.  21 6. — The  Gluteal  Region  and  Back  of  the  Thigh 
(Deep  Dissection). 


THE  LOWER  LIMB  AP7 

passes  between  the  lumbo-sacral  cord  and  the  anterior  primary 
division  of  the  first  sacral  nerve,  after  which  it  emerges  through 
the  upper  compartment  of  the  great  sacro-sciatic  foramen  above 
the  pyriformis,  and  breaks  up  into  two  divisions — superficial  and 
deep.  The  superficial  division  passes  backwards  between  the 
posterior  border  of  the  gluteus  medius  and  the  pyriformis,  and 
then  enters  the  deep  or  anterior  surface  of  the  gluteus  maximus 
near  its  origin.  Some  of  its  branches  become  cutaneous  by  piercing 
the  muscle,  and  they  anastomose  with  the  posterior  branches  of 
the  lateral  sacral  arteries  from  the  posterior  division  of  the  internal 
iliac. 

The  deep  division  passes  beneath  the  gluteus  medius,  where 
it  subdivides  into  an  upper  and  a  lower  branch.  The  upper 
branch  courses  along  the  upper  border  of  the  gluteus  minimus, 
in  company  with  the  upper  division  of  the  superior  gluteal 
nerve.  It  supplies  the  ilium  and  adjacent  muscles,  and  anasto- 
moses with  the  deep  circumflex  iliac  of  the  external  ihac  and  the 
ascending  branch  of  the  external  circumflex  of  the  arteria  profunda 
femoris.  The  lower  branch  passes  forwards  over  the  centre  of  the 
gluteus  minimus,  in  company  with  the  lower  division  of  the  superior 
gluteal  nerve.  It  supplies  the  gluteus  medius  and  gluteus  minimus 
muscles.  It  also  gives  an  articular  branch  to  the  hip-joint,  and  a 
branch  to  the  digital  fossa  which  anastomoses  with  the  sciatic, 
the  ascending  branch  of  the  internal  circumflex,  and  a  branch  of 
the  first  perforating  of  the  arteria  profunda  femoris.  The  lower 
branch  of  the  deep  division  also  anastomoses  with  the  ascending 
branch  of  the  external  circumflex. 

The  place  of  emergence  of  the  gluteal  artery  from  the  pelvis 
is  indicated  as  follows  :  the  thigh  being  rotated  inwards,  draw  a 
line  from  the  top  of  the  great  trochanter  to  the  posterior  superior 
iliac  spine,  and  take  a  point  in  this  line  at  the  junction  of  the  inner 
third  and  outer  two- thirds. 

The  gluteal  vein  terminates  in  the  internal  iliac  vein. 

Sciatic  Artery. — This  vessel  arises  from  the  anterior  division  of 
the  internal  iliac  artery.  It  descends,  usually  behind  the  internal 
pudic,  upon  the  pyriformis  and  sacral  nerves,  and  emerges  through 
the  lower  compartment  of  the  great  sacro-sciatic  foramen  below  the 
pyriformis.  It  then  passes  between  the  great  trochanter  and  tuber 
ischii,  lying  under  cover  of  the  gluteus  maximus,  on  the  inner 
side  of  the  great  sciatic  nerve,  and  resting  upon  the  gemelli, 
obturator  internus,  and  quadratus  femoris.  On  leaving  this  hollow, 
it  descends  upon  the  posterior  surface  of  the  upper  i)art  of  the 
adductor  magnus,  where  it  terminates. 

For  the  intrapelvic  portion  of  the  artery,  see  dissection  of  the 
pelvis. 

Branches. — The  extrapelvic  branches  are  as  follows  :  coccygeal, 
inferior  gluteal,  muscular,  anastomotic,  articular,  gluteal  cutaneous, 
and  comes  nervi  ischiadici. 

The  coccygeal    branch   pierces  the  great  sacro-sciatic  ligament 


4o8  A  MANUAL  OF  ANATOMY 

and  gluteus  maximus,  and  is  distributed  over  the  back  of  the  coccyx. 
The  inferior  gluteal  branch  enters  the  deep  surface  of  the  gluteus 
maximus  with  the  inferior  gluteal  nerve,  and  it  anastomoses  in 
the  muscle  with  the  superficial  division  of  the  gluteal  artery.  The 
muscular  branches  are  distributed  to  the  adjacent  external  rotator 
muscles  and  the  origins  of  the  hamstrings.  In  the  latter  muscles 
an  anastomosis  takes  place  with  the  external  terminal  branch  of 
the  obturator  artery. 

The  anastomotic  branches  are  two  in  number.  One  passes  to 
the  digital  fossa,  where  it  anastomoses  with  the  gluteal,  ascending 
branch  of  the  internal  circumflex,  and  first  perforating  arteries. 
The  other  passes  to  the  interval  between  the  quadratus  femoris  and 
adductor  magnus,  where  it  anastomoses  with  the  transverse  branch 
of  the  internal  circumflex,  the  transverse  branch  of  the  external 
circumflex,  and  the  first  perforating  arteries.  This  fourfold  anasto- 
mosis is  called  the  crucial  anastomosis. 

The  articular  branches  are  two  or  three  in  number.  They  pass 
beneath  the  gemelli  and  obturator  internus  with  the  nerve  to  the 
quadratus  femoris,  and  pierce  the  back  part  of  the  capsular  ligament 
of  the  hip- joint. 

The  gluteal  cutaneous  branches  pass  round  the  lower  border  of 
the  gluteus  maximus  with  the  gluteal  cutaneous  branches  of  the 
small  sciatic  nerve,  and  are  distributed  to  the  integument  over  the 
lower  part  of  the  muscle. 

The  comes  nervi  ischiadici  is  a  long  branch  which  descends 
for  some  distance  with  the  great  sciatic  nerve,  to  which  it  is  dis- 
tributed, and  in  which  it  anastomoses  with  the  perforating  branches 
of  the  arteria  profunda  femoris.  After  ligature  of  the  femoral 
artery  in  the  upper  third  of  the  thigh  this  branch  becomes  much 
enlarged. 

The  place  of  emergence  of  the  sciatic  artery  from  the  pelvis  is 
indicated  as  follows  :  draw  a  line  from  the  posterior  superior  iliac 
spine  to  the  outer  border  of  the  tuber  ischii,  and  take  a  point  in 
this  line  at  the  junction  of  the  middle  with  the  lower  third. 

The  sciatic  vein  terminates  in  the  internal  iliac  vein. 

The  sciatic  artery  in  the  early  embryo  is  the  leading  arterial  trunk  of  the 
lower  limb.  As  the  femoral  artery  is  developed  it  forms  a  junction  with  the 
sciatic  in  the  neighbourhood  of  the  knee,  and  so  becomes  the  chief  artery, 
and  the  part  of  the  primitive  sciatic  between  the  knee  and  the  gluteal  region 
for  the  most  part  disappears. 

Internal  Pudic  Artery. — This  vessel  arises  from  the  anterior 
division  of  the  internal  iliac,  and  at  first  lies  within  the  pelvic 
cavity.  It  is  only  the  second  part  of  the  vessel  which  is  seen  in  the 
gluteal  region,  and  which  will  be  described  here.  Having  emerged 
from  the  pelvis  through  the  lower  compartment  of  the  great  sacro- 
sciatic  foramen  below  the  pyriformis,  the  artery  passes  downwards 
for  a  short  distance,  and  crosses  over  the  back  of  the  spine  of  the 
ischium.  It  then  courses  through  the  small  sacro-sciatic  foramen, 
and  is  lost  to  view. 


THE  LOWER  LIMB  409 

Relations — Superficial  or  Posterior. — Gluteus  maximus.  Deep  or 
Anterior. — Posterior  surface  of  spine  of  ischium. 

On  either  side  of  the  artery  is  a  vena  comes.  The  pudic  nerve 
Hes  on  the  inner  side,  and  the  nerve  to  the  obturator  internus  on 
the  outer  side. 

Branches. — -Muscular,  to  gkiteus  maximus.  and  sacral,  which 
pierces  the  great  sacro-sciatic  Ugament,  and  ramifies  over  the 
back  of  the  lower  end  of  the  sacrum,  where  it  anastomoses  with 
the  coccygeal  branch  of  the  sciatic  artery. 

The  position  of  the  second  part  of  the  internal  pudic  artery  upon 
the  back  of  the  spine  of  the  ischium,  which  spine  is  about  4  inches 
below  the  posterior  superior  iliac  spine,  is  ascertained  as  follows  : 
the  thigh  being  rotated  inwards,  draw  a  line  from  the  upper  border 
of  the  great  trochanter  to  the  junction  of  the  sacrum  with  the 
coccyx,  and  take  a  point  in  this  line  at  the  junction  of  the  inner 
third  and  outer  two-thirds. 

Relation  of  Structures  on  Back  of  Spine  of  Ischium,— The  relation  from 
within  outwards  is  as  follows:  (i)  pudic  nerve,  (2)  internal  vena  comes, 
(3)  second  part  of  internal  pudic  artery,  (4)  external  vena  comes,  and 
(5)  nerve  to  obturator  internus  muscle. 

Deep  Nerves.  Superior  Gluteal  Nerve. — This  nerve  arises  from  the 
sacral  plexus,  more  particularly  from  the  dorsal  divisions  of  the 
descending  branch  of  the  fourth  lumbar,  the  fifth  lumbar,  and  the 
first  sacral  nerves.  It  passes  through  the  upper  compartment  of 
the  great  sacro-sciatic  foramen,  above  the  pyriformis,  with  the 
gluteal  artery,  and  then  beneath  the  gluteus  medius,  where  it 
divides  into  a  small  upper  and  large  lower  branch.  The  upper 
branch  accompanies  the  corresponding  division  of  the  deep  part  of 
the  gluteal  artery  along  the  upper  border  of  the  gluteus  minimus,  and 
it  supplies  the  gluteus  medius.  The  lower  branch,  passes  outwards 
over  the  centre  of  the  gluteus  minimus  with  the  lower  division  of  the 
deep  part  of  the  gluteal  artery.  It  supplies  the  gluteus  medius 
and  gluteus  minimus,  and  terminates  by  supplying  the  tensor 
fasciae  femoris. 

Inferior  Gluteal  Nerve. — This  nerve  arises  from  the  sacral  plexus, 
more  particularly  from  the  dorsal  divisions  of  the  fifth  lumbar,  and 
first  and  second  sacral  nerves.  It  passes  through  the  lower  com- 
partment of  the  great  sacro-sciatic  foramen,  below  the  pyriformis, 
in  close  contact  with  the  small  sciatic  nerve.  It  then  divides 
into  several  branches  which  enter  the  deep  surface  of  the  gluteus 
maximus  in  its  lower  third. 

Nerve  to  Obturator  Internus. — This  nerve  arises  from  the  sacral 
plexus,  more  particularly  from  the  ventral  divisions  of  the  fifth 
lumbar,  and  first  and  second  sacral  nerves.  It  passes  through  the 
lower  compartment  of  the  great  sacro-sciatic  foramen,  below  the 
pyriformis,  internal  to  the  great  sciatic  nerve  ;  over  the  posterior  sur- 
face of  the  spine  of  the  ischium,  where  it  lies  to  the  outer  side  of  the 
internal  jmdic  vessels  ;  and  through  the  small  sacro-sciatic  foramen 
to  the  intrai)elvic  part  of  the  obturator  internus.     At  the  lower 


4IO  A  MANUAL  OF  ANATOMY 

border  of  the  pyriformis  it  gives  a  branch  to  the  gemellus  superior, 
which  enters  that  muscle  on  its  deep  surface  near  the  upper  border, 
close  to  the  origin. 

Nerve  to  Quadratus  Femoris. — This  nerve  arises  from  the  sacral 
plexus,  more  particularly  from  the  ventral  divisions  of  the  descend- 
ing branch  of  the  fourth  lumbar,  the  fifth  lumbar,  and  the  first  sacral 
nerves.  It  passes  through  the  lower  compartment  of  the  great 
sacro- sciatic  foramen,  below  the  pyriformis,  where  it  lies  in  close 
contact  with  the  deep  surface  of  the  great  sciatic  nerve.  It  then 
passes,  in  succession,  beneath  the  gemellus  superior,  obturator 
internus,  gemellus  inferior,  and  quadratus  femoris,  entering  the 
last  muscle  on  its  anterior  or  deep  surface  near  the  upper  border, 
close  to  the  origin.  As  it  passes  beneath  the  gemellus  inferior,  it 
parts  with  its  branch  to  that  muscle,  which  enters  its  deep  surface 
near  the  upper  border,  close  to  the  origin. 

The  nerve  to  the  quadratus  femoris  also  supplies,  as  a  rule,  an 
articular  branch  to  the  back  of  the  hip-joint. 

Lymphatics. — The  superficial  lymphatics  of  the  gluteal  region 
terminate  in  the  inguinal  glands  (superior  or  oblique  superficial 
inguinal  glands).  The  deep  lymphatics  enter  the  pelvis,  and 
terminate  in  the  internal  iliac  glands. 

For  the  great  and  small  sacro-sciatic  ligaments  see  the  description 
of  the  pelvis  in  Abdomen  Section. 

THE  THIGH 

Back  of  the  Thigh  and  Popliteal  Space. 

Landmarks. — The  hamstring  muscles  give  rise  to  a  prominence 
along  the  back  of  the  thigh,  but  they  cannot  be  individually 
recognised  until  they  reach  the  popliteal  space.  The  great  sciatic 
nerve  is  deeply  placed,  being  under  cover  of  the  long  or  ischial 
head  of  the  biceps  femoris,  but  its  course  may  be  indicated  by 
drawing  a  line  from  the  centre  of  the  back  of  the  knee-joint  to  a 
point  between  the  great  trochanter  and  the  tuber  ischii,  rather 
nearer  the  latter  than  the  former.  The  upper  two-thirds  of  this 
line  correspond  with  the  great  sciatic  nerve,  and  the  lower  third 
with  the  internal  popliteal  nerve. 

The  situation  of  the  popliteal  space  behind  the  knee-joint  is 
indicated  by  a  depression  when  the  joint  is  flexed.  The  strong 
tendon  of  the  biceps  femoris  can  be  felt  on  the  outer  side,  as  it 
descends  to  reach  the  head  of  the  fibula,  and  in  front  of  it  the 
long  external  lateral  ligament  of  the  knee-joint  can  be  distinguished 
by  its  tense,  cord-like  feel.  Anterior  to  this  ligament  the  lower 
part  of  the  ilio-tibial  band  of  the  fascia  lata  may  be  felt.  The 
external  popliteal  nerve  is  close  to  the  inner  side  of  the  biceps 
tendon.  Lower  down  it  can  be  felt  just  below  the  head  of  the  fibula. 
On  the  inner  side  of  the  popliteal  space,  over  the  back  of  the  inner 


THE  LOWER  LIMB  411 

condyle,  three  tendons  may  be  felt.  The  most  superficial  one  is 
that  of  the  semitendinosus,  which,  though  firm,  is  narrow,  and  is 
traceable  for  some  distance  above  the  knee-joint.  Underneath  it 
is  the  tendon  of  the  semimembranosus,  and,  internal  to  this,  is  the 
slender  tendon  of  the  gracilis.  The  course  of  the  popliteal  artery 
practically  coincides  with  the  middle  line  of  the  popliteal  space, 
but  the  vessel  can  only  be  felt  when  the  joint  is  well  flexed.  During 
this  manipulation  the  popliteal  lymphatic  glands,  if  enlarged,  may 
be  detected. 

Back  of  the  Thigh. — There  is  nothing  noteworthy  in  the  super- 
ficial fascia.  The  deep  fascia  will  be  described  in  connection  with 
the  fascia  lata. 

Small  Sciatic  Nerve. — This  nerve  arises  from  the  sacral  plexus, 
more  particularly  from  the  back  of  the  first,  second,  and  third  sacral 
nerves.  It  emerges  through  the  lower  compartment  of  the  great 
sacro-sciatic  foramen,  below  the  pyriformis.  It  then  passes  down- 
wards between  the  great  trochanter  and  tuber  ischii,  resting  upon 
the  superficial  surface  of  the  great  sciatic  nerve,  and  being  under 
cover  of  the  lower  part  of  the  gluteus  maximus.  After  escaping 
from  beneath  this  muscle,  it  descends  in  the  middle  line  super- 
ficial to  the  hamstring  muscles,  and  beneath  the  deep  fascia  cover- 
ing them,  and,  passing  over  the  popliteal  space,  it  pierces  the 
deep  fascia  at  the  back  of  the  knee-jomt.  It  then  enters  the  back 
of  the  leg,  and  descends  as  low  as  about  the  centre  of  the  calf, 
in  company  with  the  external  or  short  saphenous  vein.  The 
nerve  is  entirely  sensory. 

Branches. — The  branches  are  gluteal  cutaneous,  long  pudendal 
nerve  of  Soemmering,  femoral  cutaneous,  and  sural  cutaneous. 

The  gluteal  cutaneous  branches  are  three  or  four  in  number, 
and  take  a  recurrent  course,  winding  round  the  lower  border 
of  the  gluteus  maximus,  and  supplying  the  integument  over  its 
lower  and  outer  part.  The  long  pudendal  nerve  of  Soemmering 
arises  at  the  lower  border  of  the  gluteus  maximus,  and  winds 
inwards  towards  the  anterior  part  of  the  perineum,  lying  a 
little  below  the  tuber  ischii  and  crossing  behind  the  origins 
of  the  hamstring  muscles  from  that  prominence.  It  then  pierces 
the  fascia  lata  fully  i  inch  in  front  of  the  tuber  ischii,  and, 
passing  over  the  ischio-pubic  ramus  and  through  Colles'  fascia, 
it  courses  forwards  and  inwards,  in  company  with  the  two 
su])erficial  perineal  nerves  and  the  superficial  perineal  artery, 
to  the  scrotum  in  the  male  and  the  labium  majus  in  the  female. 
In  the  anterior  part  of  the  perineum  it  communicates  with  the 
two  superficial  perineal  nerves,  and  with  them  forms  the  three 
long  scrotal  (or  labial)  nerves.  Its  branches  are  femoral  cutaneotis, 
to  the  upper  and  inner  part  of  the  thigh  on  its  posterior  aspect ;  and 
scrotal  or  labial,  to  the  scrotum  or  labium  majus,  according  to  the 
sex.  The  femoral  cutaneous  branches  of  the  small  sciatic  supply 
the  integument  ol  tlie  liack  of  the  thigh  as  low  as  the  knee-joint. 
The  sural  cutaneous  branches  arc  the  terminal  branches  of  the  nerve. 


412  A   MANUAL  OF  ANATOMY 

They  supply  the  integument  of  the  back  of  the  leg  as  low  as  about 
the  centre  of  the  calf,  and  communicate  with  branches  of  the 
ramus  communicans  tibialis  from  the  internal  popliteal. 

Muscles. — The  muscles  of  the  back  of  the  thigh  are  called  the 
hamstring  muscles,  and  are  three  in  number,  namely,  biceps 
femoris,  semitendinosus,  and  semimembranosus. 

Biceps  Femoris  or  Biceps  Flexor  Cruris — Origin. — The  muscle  arises 
by  two  heads — long  or  ischial,  and  short  or  femoral,  (i)  Long  or 
Ischial  Head. — This  arises,  in  conjunction  with  the  semitendinosus, 
from  the  lower  and  inner  impression  on  the  posterior  surface  of  the 
tuber  ischii.  (2)  Short  or  Femoral  Head. — This  arises  from  (i)  the 
outer  lip  of  the  linea  aspera,  (2)  the  upper  two-thirds  of  the  external 
supracondylar  ridge,  and  (3)  the  external  intermuscular  septum. 

Insertion. — The  upper  surface  of  the  head  of  the  fibula  in  front  of 
the  styloid  process,  by  means  of  a  round  tendon  which  sends  an 
expansion  downwards  to  the  deep  fascia  covering  the  peroneus 
longus.  A  few  fibres  are  also  inserted  into  the  external  tuberosity 
of  the  tibia. 

The  long  external  lateral  ligament  of  the  knee-joint  passes 
through  the  tendon  of  insertion,  and  divides  it  into  two  parts,  from 
which  the  ligament  is  separated  by  the  bursa  wrapped  around  it. 
The  two  divisions  of  the  tendon  are  anterior  and  posterior,  the 
anterior,  which  is  the  stronger,  being  inserted  into  the  external 
tuberosity  of  the  tibia,  as  well  as  into  the  head  of  the  fibula.  The 
expansion  to  the  deep  fascia  of  the  leg  is  derived  from  the  posterior 
division  of  the  tendon. 

Nerve-svipply. — Great  sciatic  nerve.  The  long  or  ischial  head 
receives  branches  from  the  internal  popliteal  part  of  the  nerve,  and 
the  short  or  femoral  head  from  the  external  popliteal  part. 

Action. — Acting  from  its  origin  the  muscle  is  an  extensor  of  the 
hip-joint  and  a  flexor  of  the  leg  upon  the  thigh,  and,  having  flexed 
the  knee-joint,  it  acts  as  an  external  rotator  of  the  leg.  The  long 
or  ischial  head  alone  extends  the  hip-joint.  Acting  from  its  inser- 
tion the  muscle,  by  means  of  its  long  or  ischial  head,  is  an  extensor 
of  the  pelvis  upon  the  thigh.  In  virtue  of  its  double  insertion  into 
the  head  of  the  fibula  and  external  tuberosity  of  the  tibia,  the  biceps 
femoris  contributes  materially  to  the  strength  of  the  superior  tibio- 
fibular joint  by  bracing  the  bones  together. 

In  rare  cases  the  biceps  femoris  has  a  third  head  of  origin,  which 
may  arise  from  the  tuber  ischii,  linea  aspera,  or  internal  supra- 
condylar ridge. 

Semitendinosus — Origin. — The  lower  and  inner  impression  on  the 
posterior  surface  of  the  tuber  ischii,  in  conjunction  with  the  long  or 
ischial  head  of  the  biceps  femoris. 

Insertion. — ^The  upper  part  of  the  internal  surface  of  the  shaft  of 
the  tibia,  behind  the  sartorius  and  below  the  gracilis.  From  the 
tendon  of  insertion  an  expansion  is  given  to  the  deep  fascia  of  the  leg. 

Nerve-supply. — Great  sciatic  nerve.  The  branches  come  from  the 
internal  popliteal  part  of  the  nerve. 


THE  LOWER  LIMB  413 

Action. — Acting  from  its  origin  the  muscle  is  an  extensor  of  the 
hip- joint  and  a  flexor  of  the  leg  upon  the  thigh,  and,  having  flexed 
the  knee-joint,  it  acts  as  an  internal  rotator  of  the  leg.  Acting  from 
its  insertion  it  is  an  extensor  of  the  pelvis  upon  the  thigh.  The  semi- 
tendinosus  is  intimately  connected  with  the  long  or  ischial  head  of 
the  biceps  femoris  in  the  upper  fifth  of  the  thigh,  and  its  belly  is 
crossed  at  its  centre  by  an  oblique  tendinous  intersection.  In  "the 
lower  third  of  the  thigh  the  muscle  has  a  long,  narrow,  round 
tendon,  which  broadens  out  at  its  insertion,  and  crosses  the  internal 
lateral  ligament  of  the  knee-joint.  A  bursa  intervenes  between  it 
and  that  ligament,  and  also  between  it  and  the  tendon  of  the 
sartorius. 

Semimembranosus — Origin. — By  means  of  a  broad,  flat  tendon 
from  the  upper  and  outer  impression  on  the  posterior  surface  of  the 
tuber  ischii. 

Insertion. — The  insertion  is  threefold,  as  follows  :  (i)  the  chief 
insertion  is  by  means  of  a  strong  tendon  into  the  horizontal  groove 
on  the  posterior  surface  of  the  internal  tuberosity  of  the  tibia  ; 
(2)  by  an  expansion  which  passes  upwards  and  outwards  to  the  upper 
and  back  part  of  the  external  condyle  of  the  femur,  and  which  forms 
a  large  part  of  the  posterior  ligament  of  the  knee-joint,  known  as 
the  ligamentum  posticum  Winslowii ;  (3)  by  a  broad  expansion, 
which  passes  downwards  and  outwards  to  the  oblique  or  popliteal 
line  on  the  posterior  surface  of  the  shaft  of  the  tibia.  This  ex- 
pansion covers  the  popliteus  muscle,  and  is  called  the  popliteal 
fascia. 

Nerve-supply. — Great  sciatic  nerve.  The  branches  come  from 
the  internal  popliteal  part  of  the  nerve. 

Action. — Acting  from  its  origin  the  muscle  is  an  extensor  of  the 
hip-joint  and  a  flexor  of  the  leg  upon  the  thigh,  and,  having  flexed 
the  knee-joint,  it  acts  as  an  internal  rotator  of  the  leg.  Acting 
from  its  insertion  it  is  an  extensor  of  the  pelvis  upon  the  thigh. . 

The  strong  tendon  of  origin  is  prolonged  downwards  for  some 
distance  upon  the  outer  side  of  the  muscle,  and  the  chief  tendon  of 
insertion  is  prolonged  upwards  for  some  distance  upon  its  inner  side 
The  belly  of  the  muscle  is  composed  of  short,  oblique  fasciculi,  an 
arrangement  which  gives  it  great  power  of  action,  but  a  limited 
range  of  movement.  The  chief  tendon  of  insertion  is  under  cover 
of  the  posterior  border  of  the  internal  lateral  ligament  of  the  knee- 
joint.  Previous  to  this  it  is  se])arated  from  the  internal  head  of  the 
gastrocnemius  by  the  popliteal  bursa,  which  frequently  communi- 
cates with  the  synovial  membrane  of  the  knee-joint  through  an 
ojjcning  often  present  in  the  posterior  ligament.  The  chief  tendon 
of  insertion  is  also  separated  by  a  bursa  from  the  upper  lip  of  the 
groove  on  the  posterior  surface  of  the  internal  tuberosity  of  the 
tibia. 

The  hamstring  muscles  descend  in  close  contact  through  the 
upper  three-fourths  of  the  thigh,  being  held  together  by  the  fascia 
lata.     When,    however,    they   reach   the   lower   fourth,    they  part 


414  A   MANUAL  OF  ANATOMY 

company,  the  biceps  femoris  passing  downwards  and  outwards,  and 
the  semitendinosus  and  semimembranosus  downwards  and  inwards  ; 
and  so  the  pophteal  space  begins  to  open  out. 

Great  Sciatic  Nerve. — ^This  nerve  arises  from  the  sacral  plexus, 
more  particularly  from  the  descending  branch  of  the  fourth  lumbar, 
the  fifth  lumbar,  and  the  iirst,  second,  and  upper  branch  of  the 
third  sacral  nerves.  It  emerges  from  the  pelvis  through  the  lower 
compartment  of  the  great  sacro-sciatic  foramen,  below  the  P5n.i- 
formis,  and  descends  between  the  great  trochanter  and  tuber  ischii, 
being  somewhat  nearer  the  latter  than  the  former.  It  then  passes 
down  the  middle  line  of  the  back  of  the  thigh,  under  cover  of 
the  long  or  ischial  head  of  the  biceps  femoris,  and,  about  the 
junction  of  the  middle  and  lower  thirds,  it  terminates  by  dividing 
into  internal  and  external  popliteal  nerves. 

The  great  sciatic  nerve  is  about  |  inch  broad.  Its  course  may  be 
indicated  as  follows  :  draw  a  line  from  the  centre  of  the  back  of  the 
knee-joint  to  a  point  between  the  great  trochanter  and  tuber  ischii, 
rather  nearer  the  latter  than  the  former.  The  upper  two-thirds 
of  this  line  correspond  with  the  great  sciatic  nerve,  and  the  lower 
third  with  the  internal  popliteal  nerve. 

Chief  Relations.  Superficial  or  Posterior. — Gluteus  maximus,  small 
sciatic  nerve,  and  long  or  ischial  head  of  the  biceps  femoris.  Deep 
or  Anterior. — From  above  downwards  the  nerve  is  in  contact  with 
the  following  structures  :  the  ischium,  the  nerve  to  the  quadratus 
femoris,  gemellus  superior,  obturator  internus,  gemellus  inferior, 
quadratus  femoris,  and  posterior  surface  of  adductor  magnus. 
Internal. — Semimembranosus. 

Branches. — ^The  branches  are  muscular  and  terminal. 

The  muscular  branches  arise  in  the  upper  part  of  the  thigh, 
with  the  exception  of  the  branch  to  the  short  head  of  the  biceps 
femoris,  which  arises  about  the  centre.  They  supply  the  ham- 
string muscles,  and  also  that  part  of  the  adductor  magnus  which 
descends  from  the  tuber  ischii  to  the  adductor  tubercle  of  the 
femur.  The  branch  to  this  part  of  the  adductor  magnus  arises 
in  common  with  the  nerve  to  the  semimembranosus.  The  branch 
to  the  short  head  of  the  biceps  femoris  is  derived  from  the  external 
popliteal  part  of  the  great  sciatic  nerve,  but  all  the  other  muscular 
branches  come  from  the  internal  popliteal  part. 

The  terminal  branches  are  the  mternal  and  external  popliteal 
nerves.  They  arise  about  the  junction  of  the  middle  and  lower 
thirds  of  the  thigh,  and  will  be  described  in  connection  with  the 
popliteal  space. 

The  great  sciatic  nerve  supplies  an  articular  branch  to  the  hip- 
joint  in  those  cases  where  the  nerve  to  the  quadratus  femoris  fails 
to  do  so. 

Blood-suj)ply. — ^The  nerve  is  supplied  by  the  arteria  comes 
nervi  ischiadici  from  the  sciatic,  and  the  perforating  branches  of 
the  arteria  profunda  femoris. 

The  great  sciatic  nerve  is  not  infrequently  replaced  by  the  external 


THE  LOWER  LIMB  4^5 

and    internal    popliteal    nerves.     Under    these    circumstances    the 
external  popliteal  nerve  often  pierces  the  pyriformis. 

Popliteal  Space. — The  popliteal  space  or  ham*  is  situated  behind 
the  knee-joint,  whence  it  extends  upwards  to  the  junction  of  the 
upper  three-fourths  and  lower  fourth  of  the  thigh,  and  down- 
wards to  the  junction  of  the  upper  sixth  and  lower  live-sixths  of 
the  leg.     In  shape  the  space  resembles  a  diamond. 

Boundaries.  External — {a)  Above  the  Knee-joint. — Biceps  femoris. 
[b)  Below  the  Knee-joint. — External  head  of  the  gastrocnemius,  and 
plantaris. 

Internal — (a)  Above  the  Knee-joint. — Semitendinosus,  semimem- 
branosus, gracilis,  sartorius,  and  tendon  of  the  adductor  magnus, 
in  the  order  named  from  behind  forwards,  (b)  Below  the  Knee- 
joint. — Internal  head  of  the  gastrocnemius. 

The  superior  median  angle  of  the  space  corresponds  with  the 
divergence  of  the  hamstring  muscles,  the  inferior  median  angle 
by  the  approximation  of  the  external  and  internal  heads  of  the 
gastrocnemius,  the  external  angle  by  the  meeting  between  the 
biceps  femoris  and  external  head  of  the  gastrocnemius,  and  the 
internal  angle  by  the  meeting  between  the  semimembranosus  and 
internal  head  of  the  gastrocnemius. 

The  roof  is  formed  by  the  integument.  It  contains  the  small 
sciatic  nerve,  and,  in  its  lower  part,  the  terminal  portion  of  the 
external  or  short  saphenous  vein. 

The  floor  is  formed,  from  above  downwards,  by  the  popliteal 
surface  or  trigone  of  the  femur,  the  posterior  ligament  of  the  knee- 
joint,  and  the  popliteus  muscle,  covered  by  the  popliteal  fascia. 

Contents. — The  contents  are  the  popliteal  artery  and  its  branches, 
the  pophteal  vein  and  its  tributaries  (including  the  termination  of 
the  external  or  short  saphenous  vein),  the  internal  popliteal  nerve 
and  its  branches,  the  external  popliteal  nerve  and  some  of  its 
branches,  the  geniculate  branch  of  the  obturator  nerve  (inconstant), 
lymphatic  glands,  and  a  large  amount  of  fat. 

Popliteal  Artery. — This  vessel  is  the  continuation  of  the  femoral 
artery.  It  extends  from  the  posterior  margin  of  the  femoral 
opening,  which  is  in  connection  with  the  adductor  magnus,  to  the 
lower  border  of  the  popliteus  muscle,  where  it  divides  into  anterior 
and  posterior  tibial  arteries.  The  division  takes  place  on  a  level 
with  the  lower  border  of  the  tubercle  of  the  tibia,  and  fully 
if  inches  below  the  level  of  the  upper  surface  of  the  head  of  that 
bone.  The  vessel  at  first  passes  downwards  and  outwards  until  it 
reaches  the  middle  line  of  the  limb.  It  then  takes  a  straight  course 
downwards  between  the  condyles  of  the  femur,  and  finally  it  sinks 

*  The  word  ham  is  derived  from  a  Teutonic  verb  signifying  '  to  l)e  curved 
or  crooked,'  and  it  has  been  apphed  to  the  popliteal  space  because  that  space 
is  situated  behind  the  '  crook,'  '  curve,'  or  bend  of  the  knee.  By  a  later 
extension  of  the  word  ham  it  came  to  be  applied  to  the  whole  of  the  back  of 
the  thigh — hence  the  name  hamstring,  which  is  given  to  the  muscles  of  that 
region. 


4i6 


A   MANUAL  OF  ANATOMY 


beneath  the  approximation  of  the  external  and  internal  heads  of 
the  gastrocnemius. 

General  Relations.  Superficial  or  Posterior. — Skin,  superficial  and 
deep  fasciae,  small  sciatic  nerve,  terminal  part  of  the  external  or 
short  saphenous  vein,  fat,  semimembranosus  for  about  i  inch  after 
the  artery  enters  the  space,  approximation  of  the  external  and 
internal  heads  of  the  gastrocnemius,  and  the  plantaris,  which 
crosses  the  artery  from  without  inwards.  Deep  or  Anterior. — Fat, 
popliteal  surface  or  trigone  of  the  femur,  posterior  ligament  of 
the  knee-joint,  and  popliteus  muscle,  covered  by  the  popliteal  fascia. 


Crureus 

Internal  Popliteal  Nerse 
Popliteal  Vein 

Popliteal  Arterj  — 

Biceps- 
Superior  Ext.  Articular  Aitery- 
External  Popliteal  Nerve- 


External  Head  of  Gastrocnemius-- - 

E,\ternal  Popliteal  Nerve — 

Ramus  Communicans  Fibularis 

Lateral  Cutaneous  Branch  of — -/'■'- 
External  Popliteal  Nerve 
Middle  Cutaneous  Sural  Artery 


Small  Sciatic  Nerve 
(cut) 


Semimembranosus 

Gracilis 
Semitendinosus 


Internal  Popliteal  Nerve 

Internal  Head  of 
Gastrocnemius 
Sartorius 


Ramus  Communicans 
Tibialis 


Short  Saphenous  Vein 
(cut) 


Fig.  217. — The  Popliteal  Space  (Superficial  Dissection) 


Special  Relations. — In  the  upper  part  of  the  space  the  popliteal 
vein  is  close  behind,  and  on  the  outer  side  of,  the  artery,  and  the 
internal  popliteal  nerve  is  close  behind,  and  on  the  outer  side  of,  the 
vein,  so  that  they  overlap  one  another.  In  the  middle  of  the  space 
the  popliteal  vein  is  entirely  behind  the  artery,  and  the  internal 
popliteal  nerve  is  directly  behind  the  vein.  In  the  lower  part 
of  the  space  the  popliteal  vein  is  close  behind,  and  on  the  inner  side 
of,  the  artery,  and  the  internal  popliteal  nerve  is  close  behind,  and 
on  the  inner  side  of,  the  vein,  a  relation  which  is  the  reverse  of  that 
in  the  upper  part  of  the  space.  The  geniculate  branch  of  the  obtu- 
rator nerve  (when  present),  having  pierced  the  adductor  magnus 


THE  LOWER  LIMB  417 

close  above  the  femoral  opening,  descends  at  first  upon  the  inner 
side  of  the  popliteal  artery,  and  then  in  front  of  it  as  low  as  the 
origin  of  the  central  or  azygos  artery,  where  the  nerve  leaves  the 
main  vessel  and  passes,  with  that  branch,  through  the  posterior 
ligament  of  the  knee-joint  to  the  interior  of  the  articulation. 

Branches. — The  branches  are  (i)  muscular  and  cutaneous,  and 
(2)  articular. 

The  muscular  and  cutaneous  branches  are  divided  into  a  superior 
and  an  inferior  set. 

The  superior  set  are  purely  muscular,  and  are  distributed 
to  the  lower  parts  of  the  hamstring  muscles.  They  anastomose 
with  the  lower  two  perforating  branches  of  the  arteria  profunda 
femoris. 

The  inferior  or  sural  set  are  partly  muscular  and  partly 
cutaneous.  The  muscular  branches  supply  both  heads  of  the 
gastrocnemius  and  the  plantaris.  The  cutaneous  branches  are 
three  in  number,  and  supply  the  integument  over  the  upper  half 
of  the  calf.  The  middle  cutaneous  branch  lies  in  the  groove  between 
the  two  heads  of  the  gastrocnemius  with  the  external  or  short 
saphenous  vein.  This  branch  is  sometimes  of  large  size,  and  in 
these  cases,  under  the  name  of  the  external  saphenous  artery,  it 
descends  to  the  back  of  the  external  malleolus. 

The  articular  branches  are  five  in  number — two  superior,  external 
and  internal,  one  central  or  azygos,  and  two  inferior,  external  and 
internal. 

The  superior  external  articular  artery  courses  outwards  close 
above  the  external  condyle  of  the  femur,  passing  beneath  the 
biceps  femoris  and  through  the  external  intermuscular  septum  into 
the  crureus  muscle,  where  it  breaks  up  into  branches.  These 
anastomose  with  the  following  arteries  :  (i)  descending  branch  01 
the  external  circumflex  ;  (2)  inferior  external  articular  ;  (3)  deep 
branch  of  the  anastomotica  magna  ;  (4)  superior  internal  articular  ; 
and  (5)  fourth  or  lowest  perforating  branch  of  the  arteria  profunda 
femoris. 

The  superior  internal  articular  artery  courses  inwards  close 
above  the  internal  condyle  of  the  femur,  and,  having  passed 
beneath  the  tendon  of  the  adductor  magnus,  it  enters  the  vastus 
internus,  where  it  divides  into  branches.  These  anastomose  with 
the  following  arteries :  (i)  inferior  internal  articular ;  (2)  deep 
branch  of  the  anastomotica  magna  ;  and  (3)  superior  external 
articular. 

The  central  or  azygos  articular  artery,  if  a  separate  branch, 
arises  from  the  front  of  the  main  artery,  but  it  is  often  a  branch 
of  the  superior  external  articular.  It  passes  through  the  posterior 
ligament  of  the  knee-joint  to  supply  the  synovial  memljrane  and 
ligaments  within  the  joint. 

The  inferior  external  articular  artery  courses  horizontally  out- 
wards beneath  the  tendon  of  the  biceps  femoris  and  the  long 
external  lateral  ligament  of  the  knee-joint  to  the  outer  side  of  the 

27 


4i8  A   MANUAL  OF  ANATOMY 

articulation,  where  it  divides  into  branclies.  These  anastomose  with 
the  following  arteries  :  (i)  superior  external  articular  ;  (2)  inferior 
internal  articular  ;  (3)  anterior  tibial  recurrent ;  and  (4)  posterior 
tibial  recurrent  (inconstant). 

The  inferior  internal  articular  artery  courses  at  first  obliquely 
downwards  and  inwards  along  the  upper  border  of  the  popliteus 
muscle,  and  then  passes  inwards  below  the  level  of  the  internal 
tuberosity  of  the  tibia,  where  it  lies  beneath  the  internal  lateral 
ligament  of  the  knee-joint.  On  reaching  the  inner  side  of  the 
articulation,  it  divides  into  branches  which  anastomose  with  the 
following  arteries :  (i)  superficial  branch  of  the  anastomotica 
magna  ;  (2)  superior  internal  articular  ;  (3)  inferior  external  articu- 
lar ;  (4)  anterior  tibial  recurrent ;  and  (5)  posterior  tibial  recurrent 
(inconstant). 

Varieties  of  Popliteal  Artery. — i.  The  vessel  may  divide  into  its  anterior 
and  posterior  tibial  branches  at  the  upper  border  of  the  popliteus  muscle. 

2.  The  terminal  branches  may  be  three  in  number  instead  of  two,  the 
additional  branch  being  the  peroneal  artery. 

3.  In  very  rare  cases  the  popliteal  artery  divides  high  up  into  two  branches 
of  equal  size,  which  subsequently  unite  prior  to  the  noniial  termination  of  the 
vessel. 

Popliteal  Vein. — This  vessel  commences  at  the  lower  border  of  the 
popliteus  muscle,  where  it  is  formed  by  the  union  of  the  venae 
comites  of  the  anterior  and  posterior  tibial  arteries,  and  it  termi- 
nates at  the  posterior  margin  of  the  femoral  opening,  which  is  in 
connection  with  the  adductor  magnus,  where  it  becomes  the  femoral 
vein.  The  relations  of  the  vessel  have  already  been  described.  Its 
tributaries  correspond  with  the  branches  of  the  popliteal  artery, 
with  the  addition  of  the  external  or  short  saphenous  vein. 

Internal  Popliteal  (Tibial)  Nerve. — This  nerve  is  one  of  the  ter- 
minal branches  of  the  great  sciatic,  and  it  derives  its  fibres  from 
the  ventral  divisions  of  the  descending  branch  of  the  fourth  lumbar, 
the  fifth  lumbar,  the  first  and  second  sacral,  and  the  upper  branch 
of  the  third  sacral  nerves.  It  extends  from  the  superior  angle  of 
the  popliteal  space  to  the  lower  border  of  the  popliteus  muscle, 
where  it  becomes  the  posterior  tibial  nerve.  The  relations  of  this 
nerve  have  been  given  in  connection  with  the  popliteal  artery. 

Branches. — The  branches  are  articular,  cutaneous,  and  muscular. 

The  articular  branches  are  three  in  number  (sometimes  two), 
as  follows  :  superior  (inconstant),  accompanying  the  superior 
internal  articular  artery  ;  central  or  azygos,  going  with  the  corre- 
sponding artery  ;  and  inferior,  accompanying  the  inferior  internal 
articular  artery. 

The  cutaneous  branch  is  called  the  ramus  communicans  tibialis. 
It  descends  in  the  middle  line  beneath  the  deep  fascia  as  far 
as  the  centre  of  the  calf.  Here  it  pierces  the  deep  fascia,  and 
shortly  afterwards  it  is  joined  by  the  ramus  communicans  fibularis 
from  the  external  popliteal.  In  this  manner  the  external  or  short 
saphenous  nerve  is  formed. 


THE  LOWER  LIMB 


419 


Femoral  Head 

of  Biceps 

Ext.  Popliteal 

Nerve 


Vastus  Internus 


Superior  Internal 
Articular  Nerve 

Superior  Internal 
•\rticular  Artery 


Int.  Head  of 
Gastrocnemius 

Semimem- 
branosus 
Semitendinosus 

Sartorius 
Gracilis 


Inferior  Internal 
\rticular  Artery 


ernal  Popliteal  Nerve 


Fig.  218.— The  ['oi'liteal  Space  (Deep  Dissection). 


27- 


420  A   MANUAL  OF  ANATOMY 

The  muscular  (sural)  branches  are  usually  five  in  number, 
which  are  distributed  as  follows  :  one  to  the  external  head  of 
the  gastrocnemius,  one  to  the  plantaris  (which  sometimes  comes 
from  the  preceding),  one  to  the  internal  head  of  the  gastroc- 
nemius, one  to  the  soleus,  and  one  to  the  popliteus.  The  nerve  to 
the  popliteus  descends  over  the  popliteal  fascia,  lying  to  the  outer 
side  of  the  popliteal  vessels.  On  arriving  at  the  lower  border  of 
the  popliteus,  it  turns  round  that  border  and  enters  the  deep  surface 
of  the  muscle.  This  nerve,  besides  supplying  the  popliteus,  furnishes 
the  following  branches  :  articular  to  the  superior  tibio-fibular  j  oint ; 
medullary,  which  enters  the  large  nutrient  or  medullary  foramen 
on  the  back  of  the  tibia  ;  vascular  to  the  anterior  and  posterior 
tibial  arteries  ;  and  interosseous.  The  interosseous  branch  is  a  long 
nerve  which  descends  in  the  interosseous  membrane  to  terminate  in 
the  inferior  tibio-fibular  joint. 

External  Popliteal  or  Peroneal  (Fibular)  Nerve. — This  nerve  is 
the  other  terminal  branch  of  the  great  sciatic,  and  it  derives  its 
fibres  from  the  dorsal  divisions  of  the  descending  branch  of  the 
fourth  lumbar,  the  fifth  lumbar,  and  the  first  and  second  sacral 
nerves.  It  commences  at  the  superior  angle  of  the  popliteal  space, 
and  descends  obliquely  downwards  and  outwards  as  low  as  the 
back  of  the  neck  of  the  fibula,  where  it  passes  forwards  between 
the  bone  and  the  peroneus  longus,  to  end  on  the  outer  side  of 
the  fibular  neck  in  its  terminal  branches.  The  nerve  lies  at  first 
close  to  the  inner  border  of  the  biceps  femoris,  and  then  it  rests 
upon  the  back  of  the  external  head  of  the  gastrocnemius,  between 
which  and  the  biceps  tendon  it  may  be  regarded  as  lying. 

Branches. — ^The  branches  are  articular,  cutaneous,  and  terminal. 

The  articular  branches  are  three  in  number,  as  follows  :  superior, 
accompanying  the  superior  external  articular  artery ;  inferior, 
going  with  the  inferior  external  articular  artery,  which  it  reaches 
as  the  vessel  is  about  to  pass  beneath  the  biceps  tendon  ;  and 
recurrent  articular,  accompanying  the  anterior  tibial  recurrent 
artery. 

The  cutaneous  branches  are  two  in  number,  as  follows  :  lateral 
cutaneous  branch,  which  supplies  the  integument  of  the  outer 
side  of  the  leg  over  about  its  upper  two- thirds,  as  well  as  the 
adjacent  integument  of  the  sural  region  ;  and  ramus  communicans 
fibularis,  which  passes  downwards  and  inwards  over  the  external 
head  of  the  gastrocnemius  and  beneath  the  deep  fascia  to  the  centre 
of  the  calf,  where  it  pierces  the  deep  fascia  and  shortly  afterwards 
joins  the  ramus  communicans  tibialis,  to  form  the  external  or  short 
saphenous  nerve. 

The  terminal  branches  are  three  in  number,  as  follows :  recurrent 
articular,  already  referred  to  ;  anterior  tibial  (see  p.  481)  ;  and 
musculo-cutaneous  (see  p.  475). 

For  the  geniculate  branch  of  the  obturator  nerve,  see  p.  447. 

Popliteal  Lymphatic  Glands. — These  are  usually  four  in  number, 
and   lie    in    close   contact   with    the   popliteal    artery,    one    being 


THE  LOWER  LIMB  421 

superficial  to  the  vessel,  one  beneath  it,  and  the  remaining  two  being 
disposed  laterally.  They  receive  their  afferent  lymphatics  from  the 
following  sources :  (i)  sole  of  the  foot ;  (2)  deep  part  of  the  back  of 
the  leg  :  (3)  some  of  the  superficial  lymphatics  accompanying  the  ex- 
ternal or  short  saphenous  vein  ;  and  (4)  the  two  efferent  lymphatics 
which  proceed  from  the  anterior  tibial  lymphatic  gland  on  the  front 
of  the  interosseous  membrane  at  its  upper  part.  The  course  of 
these  two  efferent  lymphatics  is  backwards  above  the  interosseous 
membrane,  or  through  the  superior  hiatus  in  it. 

The  efferent  lymphatics  of  the  popHteal  glands  ascend  to  become 
the  afferent  lymphatics  of  the  deep  femoral  glands,  which  lie  in  con- 
tact with  the  femoral  vein  near  Poupart's  ligament. 

Front  and  Inner  Side  of  the  Thigh. 

Landmarks.— r/ngA.— The  anterior  superior  spinous  process  of  the 

ilium  is  situated  at  the  anterior  extremity  of  the  iliac  crest,  and  can 
readily  be  felt.  It  is  the  point  from  which  the  measurement  of 
the  lower  limb  is  taken.  It  is  also  a  guide  to  the  great  trochanter 
of  the  femur,  that  prominence  being  situated  about  4  inches  below 
the  spine,  and  about  4  inches  behind  a  line  let  fall  vertically  from 
it.  The  crest  of  the  ilium  extends  backwards  in  a  curved  manner 
from  the  anterior  superior  spinous  process.  Poupart's  ligament 
passes  between  the  anterior  superior  iliac  spine  and  the  pubic 
spine.  It  can  be  felt  as  a  tense,  firm  band,  especially  when  the 
thigh  is  extended,  abducted,  and  rotated  outwards.  Immediately 
below  it  the  inguinal  lymphatic  glands  may  be  felt.  Poupart's 
ligament,  when  traced  inwards,  conducts  the  finger  to  the  pubic 
spine,  which  is  situated  at  the  lower  and  inner  part  of  the  anterior 
abdominal  wall  about  i|  inches  outside  the  upper  part  of  the  sym- 
physis pubis.  It  is  sometimes  a  sharp-pointed  process,  and  then  it 
can  readily  be  felt  beneath  the  integument.  In  most  bodies,  how- 
ever, it  takes  the  form  of  a  more  or  less  indistinct  tubercle,  and, 
especially  in  corpulent  bodies,  it  cannot  be  felt.  In  such  cases  the 
scrotal  integument  may  be  invaginated  with  the  finger  so  as  to 
raise  the  adipose  tissue  from  over  the  spine.  If  it  cannot  be  felt  in 
this  way,  the  thigh  should  be  well  abducted  to  render  prominent  the 
adductor  longus  muscle,  the  tendon  of  origin  of  which  will  serve  as  a 
guide  to  the  spine,  which  lies  above  and  to  the  outer  side  of  it.  The 
pubic  spine  is  the  guide  to  the  following  openings  :  the  external 
abdominal  ring,  which  lies  immediately  above  and  to  the  outer  side 
of  it  ;  the  crural  or  femoral  ring,  which  is  situated  fully  i  inch 
external  to  the  spine  in  a  line  drawn  outwards  from  it  across  the 
front  of  the  thigh  ;  and  the  saphenous  opening,  which  is  situated 
below,  and  a,  little  external  to,  it. 

The  pubic  crest  extends  inwards  for  about  i  inch  from  the 
pubic  sjiine,  and  terminates  in  the  pubic  angle  above  the  sym- 
physial  surface  of  the  os  pubis.  The  crest  may  be  felt  if  the  scrotal 
integument  is  invaginated  and  the  little  finger  passed  into  the  ex- 


422  A  MANUAL  OF  ANATOMY 

ternal  abdominal  ring,  of  wliich  the  crest  forms  the  base.  The  angle 
cannot  usually  be  felt.  The  ischio-pubic  ramus  can  be  felt  extending 
from  the  tuber  ischii  at  the  back  of  the  limb  to  the  lower  part  of  the 
symphysis  pubis.  The  saphenous  opening  is  situated  below  and 
external  to  the  pubic  spine,  and  it  extends  downwards  for  about 
i^  inches  below  the  inner  third  of  Poupart's  ligament.  At  the 
lower  extremity  of  the  opening  the  superficial  femoral  or  saphenous 
lymphatic  glands  may  be  felt.  The  most  prominent  part  of  the 
head  of  the  femur  will  be  felt  immediately  below  Poupart's  liga- 
ment, at  a  point  just  external  to  its  centre. 

The  great  trochanter  is  situated  about  4  inches  below  the  anterior 
superior  iliac  spine,  and  about  4  inches  behind  a  line  let  fall  vertically 
from  it.  Its  outline  is  more  or  less  obscured  by  the  muscles  which 
cover  it,  but  the  following  guides  may  serve  to  localize  the  pro- 
minence : 

Holden's  Guide. — ^The  top  of  the  great  trochanter  is  pretty  nearly 
on  a  level  with  the  pubic  spine  in  the  recumbent  posture. 

Nelaton's  Line. — This  is  a  line  drawn  from  the  anterior  superior 
iliac  spine  to  the  most  prominent  part  of  the  tuber  ischii.  It  co- 
incides with  the  top  of  the  great  trochanter,  and  runs  through  the 
centre  of  the  acetabulum. 

Bryant's  Test- Line. — The  subject  being  in  the  horizontal  position,  a  triangle 
(ilio-femoral)  is  constructed  in  the  following  manner :  draw  two  lines  from  the 
anterior  superior  spine  of  the  ilium,  one  being  vertical  and  traversing  the  outside 
of  the  hip  to  the  horizontal  plane  of  the  body,  and  the  other  impinging  on  the 
tip  of  the  great  trochanter.  Then  construct  the  base  by  drawing  a  line  from, 
and  at  right  angles  to,  the  vertical  line  to  the  trochanter.  The  base  represents 
Bryant's  test-line  for  shortening  of  the  neck  of  the  femur.  '  Any  shortening  of 
this  line,  on  comparing  it  with  the  same  taken  on  the  uninjured  side,  indicates 
with  precision  a  shortening  of  the  neck  of  the  thigh-bone.' 

The  position  of  Scarpa's  triangle  is  indicated  by  a  slight  depression 
which  exists  below  Poupart's  ligament.  The  outline  of  the  adductor 
longus  muscle  is  easily  seen  when  the  limb  is  firmly  abducted.  If 
the  prominence  thereby  produced  is  followed  upwards,  the  narrow 
round  tendon  of  origin  of  the  muscle  is  readily  felt  at  a  point  on 
the  body  of  the  os  pubis  below  and  internal  to  the  pubic  spine. 
The  rectus  femoris  gives  rise  to  a  median  vertical  prominence  on 
the  front  of  the  thigh.  The  well-marked  prominence  over  the  lower 
fourth  of  the  thigh  on  its  inner  aspect  is  due  to  the  vastus  internus 
muscle.  When  the  knee  is  flexed,  the  narrow  round  tendon  of  the 
adductor  magnus  can  be  felt  as  it  descends,  posterior  to  the  vastus 
internus,  to  reach  the  adductor  tubercle  of  the  femur. 

Knee. — ^The  outline  of  the  patella  is  readily  felt  along  with  that 
of  the  ligamentum  patellae,  which  passes  from  the  lower  pointed 
end  of  the  patella  to  the  tubercle  of  the  tibia. 

The  internal  condyle  of  the  femur  forms  a  large  prominence  looking 
inwards.  On  its  inner  surface  the  blunt  internal  tuberosity  is  easily 
felt.  At  its  upper  and  back  part  the  adductor  tubercle  can  be  felt, 
when  the  knee-joint  is  flexed,  with  the  narrow  round  tendon  of  the 
adductor  magnus  taking  insertion  into  it.     The  upper  border  of  the 


THE  LOWER  LIMB  423 

patellar  surface  of  the  femur  may  be  felt  when  the  knee-joint  is 
flexed,  but  it  is  somewhat  obscured  by  the  tendon  of  the  quadriceps 
extensor  cruris.  It  is  oblique  in  direction,  and  rises  higher  externally 
than  internally.  The  adductor  tubercle  is  on  the  same  level  as  the 
outer  part  of  the  upper  border  of  the  patellar  surface.  A  line 
connecting  these  two  points,  and  at  the  same  time  cutting  the  ad- 
ductor tubercle  into  two,  indicates  the  line  of  junction  of  the  lower 
epiphysis  of  the  femur  with  the  shaft  at  the  twentieth  year.  The 
external  condyle  of  the  femur,  though  not  very  prominent,  may 
be  felt.  The  external  tuberosity  of  the  tibia  forms  a  marked  pro- 
minence at  the  outer  and  anterior  part  of  the  knee-joint,  and  it  here 
presents  a  tubercle,  or  ridge,  for  the  ilio-tibial  band  of  the  fascia 
lata.  The  head  of  the  fibula  is  easily  felt  below  and  behind  the 
external  tuberosity  of  the  tibia.  The  tubercle  of  the  tibia  is  felt  at 
the  upper  end  of  the  sharp  anterior  border  or  crest  of  the  bone. 
Its  upper  border  is  on  the  same  level  as  the  upper  part  of  the  head 
of  the  fibula.  It  is  to  be  noted  that  the  internal  tuberosity  of  the 
tibia  has  a  slight  inclination  backwards  as  well  as  inwards. 

The  lower  limit  of  the  synovial  membrane  of  the  knee-joint 
corresponds  with  the  level  of  the  tubercle,  or  ridge,  on  the  anterior 
and  outer  part  of  the  external  tuberosity  of  the  tibia  for  the  attach- 
ment of  the  ilio-tibial  band  of  the  fascia  lata.  If  this  tubercle 
cannot  be  felt,  a  transverse  line  just  above  the  head  of  the  fibula 
indicates  the  lower  limit  of  the  membrane.  In  this  direction  the 
membrane  clothes  the  deep  or  posterior  surface  of  the  ligamentum 
patellae  in  its  upper  half.  Behind  the  lower  end  of  this  ligament 
there  is  a  bursa  separating  it  from  the  upper  smooth  part  of  the 
tubercle  of  the  tibia.  Superiorly  the  synovial  membrane  extends 
upwards  above  the  patella  in  the  form  of  a  large  pouch  upon  the 
front  of  the  femur  for  about  2  inches  above  the  upper  border  of 
the  patellar  surface  of  the  bone.  This  pouch  lies  beneath  the  tendon 
of  the  quadriceps  extensor  cruris,  and  communicates  with  a  bursa 
which  is  situated  immediately  above  it,  and  which  extends  upwards 
for  about  another  inch  beneath  the  tendon. 

In  extension  of  the  knee-joint  the  patella  is  situated  above  the 
level  of  the  condyles  of  the  femur.  In  flexion  it  lies  over  the  inter- 
condylar fossa.  In  extreme  flexion  the  patella  articulates  chiefly 
with  the  semilunar  impression  on  the  outer  part  of  the  tibial  surface 
of  the  internal  condyle  of  the  femur,  close  to  the  intercondylar  fossa. 
The  particular  part  of  the  patella  which  so  articulates  is  the  inner 
vertical  zone  on  its  posterior  surface,  immediately  adjoining  its 
internal  border.  In  flexion  of  the  joint  there  is  a  depression  on 
either  side  of  the  ligamentum  patellae,  and  also  on  either  side  of  the 
jmtella  itself,  the  latter  depression  being  greater  on  the  inner  than 
on  the  outer  side.  In  this  position  of  the  joint  the  anterior  margin 
of  each  tibial  tuberosity  is  readily  felt,  and,  above  each,  there  is  a 
hollow  which  sejmrates  it  from  the  corres])onding  femoral  condyle. 
In  extension  of  the  joint  the  dej)ression  on  either  side  of  the  patella 
is  also  manifest,  being,  as  in  flexion,  greater  on  its  inner  side.     The 


424  A   MANUAL  OF  ANATOMY 

depression  on  either  side  of  the  Hgamentum  patellse,  however,  is  not 
present,  this  being  due  to  the  lateral  dispersion  of  the  fat  which 
normally  lies  underneath  the  ligamentum  patellae. 

Cutaneous  Nerves.  Crural  Branch  of  Genito-crural  Nerve. — 
The  genito-crural  nerve  is  a  branch  of  the  lumbar  plexus,  its  fibres 
being  derived  from  the  first  lumbar  and  the  ventral  division  of  the 
second  lumbar  nerves.  Its  crural  branch  emerges  beneath  Poupart's 
ligament  immediately  to  the  outer  side  of  the  femoral  artery,  and 
within  the  crural  sheath.  Having  supplied  a  twig  to  the  coats 
of  that  vessel,  it  pierces  the  sheath  and  the  fascia  lata,  to  be  dis- 
tributed to  the  integument  over  Scarpa's  triangle. 

Inguinal  Nerve  (Ilio-inguinal). — This  is  a  branch  of  the  lumbar 
plexus,  its  fibres  being  derived  from  the  first  lumbar  nerve.  It 
emerges  from  the  inguinal  canal  through  the  external  abdominal 
ring,  where  it  lies  directly  to  the  outer  side  of  the  spermatic  cord, 
or  round  ligament  of  the  uterus,  according  to  the  sex.  It  then 
pierces  the  intercolumnar  fascia,  and  is  distributed  to  the  integu- 
ment of  the  inner  side  of  the  thigh  in  the  upper  third,  and  to  the 
adjacent  integument  of  the  scrotum  in  the  male  and  the  labium 
majus  in  the  female. 

External  Cutaneous  Nerve. — This  is  a  branch  of  the  lumbar 
plexus,  its  fibres  being  derived  from  the  dorsal  divisions  of  the 
second  and  third  lumbar  nerves.  It  emerges  beneath  the  outer 
end  of  Poupart's  ligament,  and  shortly  afterwards  divides  into  a 
small  posterior  and  a  large  anterior  division.  The  posterior  division 
is  distributed  to  the  integument  of  the  outer  side  of  the  thigh  in 
the  upper  fourth,  and  also  to  the  integument  of  the  outer  and  lower 
part  of  the  gluteal  region.  The  anterior  division  is  at  first  contained 
in  a  tube  of  the  fascia  lata  for  about  4  inches,  and  then  it  enters 
the  integument  of  the  outer  side  of  the  thigh  which  it  supplies, 
reaching  in  some  cases  as  low  as  the  patella,  and  taking  part  in 
the  patellar  plexus. 

Middle  Cutaneous  Nerve.  —  This  is  a  branch  of  the  anterior 
division  of  the  anterior  crural  nerve.  It  pierces  the  fascia  lata  in 
two  divisions,  outer  and  inner,  about  4  inches  below  Poupart's 
ligament.  The  outer  division  usually  passes  through  the  upper 
part  of  the  sartorius,  and  then  descends  with  the  inner  division 
to  supply  the  integument  of  the  front  of  the  thigh  in  the  lower 
two-thirds.  The  two  divisions  extend  as  low  as  the  patella,  where 
they  take  part  in  the  patellar  plexus. 

Internal  Cutaneous  Nerve. — This  is  a  branch  of  the  anterior 
division  of  the  anterior  crural  nerve.  It  crosses  over  the  femoral 
artery  from  without  inwards  near  the  apex  of  Scarpa's  triangle, 
either  as  one  nerve,  or  in  its  two  final  divisions,  anterior  and  posterior. 
These  two  divisions  now  descend  on  the  inner  side  of  the  thigh 
beneath  the  fascia  lata,  and  along  the  line  of  the  long  saphenous 
vein.  At  the  junction  of  the  middle  and  lower  thirds  of  the  thigh 
the  anterior  division  pierces  the  fascia  lata,  and  descends  near  the 
tendon  of  the  adductor  magnus  to  the  inner  side  of  the  knee-joint, 


THE  LOWER  LIMB  425 

supplying  the  integument  of  the  inner  side  of  the  thigh  in  the 
lower  third.  It  finally  turns  outwards  over  the  patella,  and  enters 
into  the  patellar  plexus.  The  posterior  division  descends  along  the 
posterior  border  of  the  sartorius,  and  keeps  beneath  the  fascia  lata 
until  it  reaches  the  level  of  the  internal  condyle  of  the  femur.  Here 
it  pierces  the  fascia  lata,  and  descends  to  the  inner  side  of  the  leg, 
lying  posterior  to  the  long  saphenous  nerve,  and  supplying  the 
integument  as  low  as  the  centre.  The  internal  cutaneous  nerve, 
whilst  in  Scarpa's  triangle,  gives  off  two  or  three  cutaneous  branches, 
which,  having  pierced  the  fascia  lata,  cross  the  femoral  artery 
and  are  distributed  to  the  integument  of  the  inner  side  of  the 
thigh  in  the  middle  third,  along  the  course  of  the  long  saphenous 
vein.  The  posterior  division  of  the  nerve  gives  off  a  branch  to  the 
subsartorial  plexus  about  the  centre  of  the  thigh  on  its  inner  aspect. 

Internal  or  Long  Saphenous  Nerve. — This  is  a  branch  of  the  pos- 
terior division  of  the  anterior  crural  nerve,  and  is  deeply  placed 
as  far  as  the  knee-joint.  In  the  lower  two-thirds  of  Scarpa's 
triangle  it  lies  close  to  the  outer  side  of  the  femoral  artery,  and  in 
Hunter's  canal  it  gets  in  front  of  that  vessel.  It  leaves  Hunter's 
canal  at  its  lower  end  by  piercing  the  aponeurotic  roof,  in  company 
with  the  superficial  branch  of  the  anastomotica  magna  artery,  and 
then  it  descends  beneath  the  sartorius  to  the  inner  side  of  the  knee- 
joint.  Here  it  pierces  the  fascia  lata  on  a  level  with  the  lower 
border  of  the  sartorius,  and  enters  the  inner  side  of  the  leg,  along 
which  it  courses,  usually  in  two  divisions,  in  company  with  the 
long  saphenous  vein,  the  larger  division  being  behind  that  vessel, 
and  the  smaller  in  front.  At  the  ankle-joint  the  larger  division 
passes  in  front  of  the  internal  malleolus,  and  then  along  the  inner 
border  of  the  foot  as  far  as  the  centre.  The  long  saphenous  nerve, 
in  passing  through  Hunter's  canal,  gives  off  a  branch  which  pierces 
the  aponeurotic  roof,  and  enters  into  the  subsartorial  plexus.  At 
the  level  of  the  internal  femoral  condyle  it  furnishes  its  patellar 
branch.  This  passes  through  the  sartorius  and  fascia  lata,  and  is 
distributed  to  the  integument  over  the  front  of  the  knee,  where 
it  takes  part  in  the  patellar  plexus. 

In  its  further  course  beyond  the  knee-joint  the  nerve  supplies 
branches  to  the  integument  of  the  inner  side  of  the  leg,  back  of  the 
leg  in  its  lower  and  inner  part,  internal  malleolus,  and  inner  side 
of  the  foot  as  far  as  the  centre.  In  the  upper  part  of  the  leg  it 
communicates  with  the  posterior  division  of  the  internal-  cutaneous 
nerve,  and  on  the  inner  side  of  the  foot  it  is  connected  with  the 
musculo-cutaneous. 

Obturator  Nerve. — The  anterior  division  of  the  obturator  nerve 
usually  furnishes  a  branch  which  pierces  the  fascia  lata  about  the 
centre  of  the  thigh,  between  the  posterior  border  of  the  sartorius 
and  the  anterior  border  of  the  gracilis,  to  be  distributed  to  the 
int(;gumf'nt  for  a  variable  distance. 

Patellar  Plexus. — This  free  interlacement  of  nerves  is  so  named 
because    it  is  situated  over   the   anterior  surface  of  the  patella. 


426 


A   MANUAL  OF  ANATOMY 


Obliquus  Externus  Abdominis 
Gluteus  Medius. 


Tensor  Fasciae  Femoris 

Psoas  Magnus 

Pectineus 

Sartorius- 

Adductor  Longus 
Gracilis 

Rectus  Femoris 

Ilio-tibial  Band 

Vastus  Externus- 
Vastus  Internus 


Ext.  Abdominal  Ring 


Ligamentum  Patella; 


Gastrocnemius 


Peroiieus  Longus 
Soleus 

Ext.  Longus  Digitorum 


Ext.  Proprius  Hallucis 

Tibialis  Amicus 

Peroneus  Tertius 

Anterior  Annular 

Ligament 

Fundiform  Ligament 

of  Retzius  ,,, 


-  Ext.  Cutaneous  Nerve 

_  Crural  Branch  of  Genito- 

crural  Nerve 
^  Inguinal  Nerve 

Saphenous  Opening 
-.  Mid.  Cutaneous  Nerve 


-  Int.  Saphenous  Vein 

—  Int.  Cutaneous  Nerve 
(Outline) 


-    Ant.  Branch  of  Interna! 
Cutaneous  Nerve 


Patellar  Plexus  of  Nerves 
Patellar  Branch  of  Internal 

Saphenous  Nerve 
Int.  Saphenous  Nerve 
Int.  Saphenous  Vein 
Post.  Branch  of  Internal 
Cutaneous  Nerve 


-  Cutaneous  Part  of  Musculo- 
cutaneous Nerve 

-.Calcaneo-plantar  Nerve 

-  Int.  .Saphenous  Nerve 
(Terminal  Part) 


Fig.  219. — MtJSCLES  and  Cutaneous  Nerves  of  the  Lower  Limb 
(Anterior  Aspect). 


THE  LOWER  LIMB  427 

The  nerves  which  take  part  in  it  are  as  follows  :  the  patellar 
branch  of  the  long  saphenous ;  both  divisions  of  the  middle 
cutaneous  :  the  anterior  division  of  the  internal  cutaneous  ;  and 
the  anterior  division  of  the  external  cutaneous  (which,  however, 
is  not  constant). 

Subsartorial  Plexus. — This  plexus  is  situated  in  the  middle  third 
of  the  thigh  on  its  internal  aspect,  and  lies  beneath  the  sartorius 
upon  the  aponeurotic  covering  of  Hunter's  canal.  The  nerves 
which  take  part  in  its  formation  are  as  follows  :  the  long  saphenous  ; 
the  posterior  division  of  the  internal  cutaneous  ;  and  the  superficial 
or  anterior  division  of  the  obturator.  The  branches  furnished  by 
this  plexus  are  distributed  to  the  integument  of  the  inner  side  of 
the  thigh  for  about  its  middle  third. 

Superficial  Fascia. — The  only  point  to  be  noted  in  connection 
with  the  superficial  fascia  is  that,  for  about  3  inches  below  Poupart's 
ligament,  it  is  divisible  into  two  layers — subcutaneous  and  deep. 
The  subcutaneous  layer  is  fatty,  and,  when  traced  upwards,  becomes 
continuous  with  the  fascia  of  Camper  on  the  anterior  abdominal 
wall.  The  deep  layer  is  a  very  delicate  membrane,  which  is  best 
seen  on  the  inner  side  of  and  beneath  the  long  saphenous  vein, 
as  that  vessel  lies  between  it  and  the  subcutaneous  layer.  It  can 
be  traced  upwards  to  a  line  about  \  inch  below  Poupart's  ligament, 
where  it  blends  with  the  fascia  lata.  In  passing  upwards  it  covers 
the  saphenous  opening,  to  the  outer  margin  of  which  it  is  closely 
bound  by  fibrous  bands,  more  especially  over  the  middle  third. 
The  part  of  this  layer  which  lies  over  the  saphenous  opening  is 
called  the  cribriform  fascia,  because  it  presents  numerous  foramina 
for  the  passage  of  the  following  structures  :  (i)  the  long  saphenous 
vein  ;  (2)  the  efferent  lymphatics  of  the  inguinal  and  superficial 
femoral  glands  ;  (3)  the  superior  external  pudic  artery  ;  and  (4)  the 
superficial  epigastric  and  superficial  circumflex  iliac  arteries.  The 
latter  two  vessels,  however,  sometimes  pierce  the  fascia  lata  forming 
the  outer  margin  of  the  saphenous  opening. 

Lymphatic  Glands. — The  glands  of  the  upper  part  of  the  front 
of  the  thigh  are  arranged  in  two  groups — superficial  and  deep. 

Superficial  Group. — The  glands  which  comprise  this  group  are 
arranged  in  two  sets — inguinal  and  superficial  femoral  or  saphenous. 

The  inguinal  glands  are  otherwise  called  the  superior  or  oblique 
superfi,cial  inguinal  glands.  They  are  situated  immediately  below 
Poupart's  ligament,  and  lie  underneath  the  subcutaneous  layer 
of  the  sujjerficial  fascia,  their  long  axes  being  oblique.  They 
are  usually  from  six  to  eight  in  number,  and  the  innermost  two 
or  three,  which  lie  internal  to  the  upper  part  of  the  saphenous 
opening  in  the  vicinity  of  the  pubic  spine,  are  spoken  of  as  the 
pubic  glands.  The  inguinal  glands  receive  their  alYerent  lymj)hatics 
from  the  following  sources  : 

1.  The  superficial  lymphatics  of  the  anterior  abdomiiial  wall  below  the 
level  of  the  umbilicus. 

2.  The  superficial  lymphatics  of  the  gluteal  region. 


428 


A  MANUAL  OF  ANATOMY 


3.  The  outer  and  back  part  of  the  thigh 
(superficial). 

4.  The  upper  and  inner  part  of  the  thigh 
(superficial). 

5.  The  scrotum  in  the  male  (except  its  back 
part),  and  the  external  genital  organs  in  the 
female. 

6.  The  superficial  lymphatics  of  the  penis, 
including  those  of  the  glans  penis,  some  of 
those  of  the  membranous  portion,  and  all  those 
of  the  spongy  portion,  of  the  urethra,. 

7.  The  superficial  lymphatics  of  the  peri- 
neum, the  lower  part  of  the  anal  canal,  and 
the  anus. 

8.  The  lower  third  of  the  vagina,  and  the 
female  urethra. 


The  efferent  lymphatics  of  the  inguinal 
glands  pierce  the  cribriform  fascia  and 
anterior  wall  of  the  crural  sheath,  and 
terminate  in  two  ways.  Some  of  them 
become  the  afferent  lymphatics  of  the 
deep  femoral  glands,  whilst  others  enter 
the  abdominal  cavity,  where  they  be- 
come the  afferent  lymphatics  of  the 
external  iliac  glands. 

Blood-supply. — The  inguinal  glands 
derive  their  arterial  supply  from  the 
superficial  circumflex  iliac,  superficial 
epigastric,  and  superior  or  superficial 
external  pudic  branches  of  the  common 
femoral  artery. 

The  superficial  femoral  or  saphenous 
glands  are  otherwise  called  the  inferior 
or  vertical  superficial  ingiiinal  glands. 
They  are  situated  at  the  lower  end 
of  the  saphenous  opening,  where  they 
lie,  with  their  long  axes  vertical,  on 
either  side  of  the  terminal  part  of  the 
internal  or  long  saphenous  vein,  under- 
neath the  subcutaneous  layer  of  the 
superficial  fascia.  They  are  usually 
from  four  to  six  in  number,  and  they 
receive  their  afferent  lymphatics  from 
the  following  sources  : 

1.  The  superficial  lymphatics  of  the  foot  and 
leg,  except  a  few  of  those  which  accompany  the 
external  or  short  saphenous  vein,  these  latter 
terminating  in  the  pophteal  glands. 

2.  The  superficial  lymphatics  of  the    thigh, 

Fig.   220. The   Superficial    except  those  from  (a)  the  outer  and  back  part, 

Lymphatics  of  the  Lower     and    (b)    the    upper    and    inner    part,    which 

LxMB,  terminate  in  the  inguinal  glands. 


THE  LOWER  LIMB  429 

The  efferent  Ij'mphatics  of  the  superficial  femoral  or  saphenous 
glands  pierce  the  cribriform  fascia,  and  terminate  in  a  manner 
similar  to  those  of  the  inguinal  glands. 

Blood-supply. — These  glands  derive  their  arterial  supply  from 
two  or  three  saphenous  branches  of  the  superficial  femoral  artery. 

Deep  Group. — These  are  called  the  deep  femoral  glands  (deep 
inguinal  glands).  They  are  from  three  to  four  in  number,  and 
are  situated  within  the  crural  sheath.  One  of  them  lies  in  the 
crural  canal  at  its  upper  end,  being  attached  to  the  inferior  convex 
surface  of  the  septum  crurale.  The  others  are  situated  in  the 
middle  compartment  of  the  crural  sheath,  where  they  lie  on  the 
inner  side  of  the  femoral  vein.  The  deep  femoral  glands  receive 
their  afferent  l3-mphatics  from  the  following  sources  : 

1.  The  inguinal  glands. 

2.  The  superficial  femoral  or  saphenous  glands. 

3.  The  deep  lymphatics  of  the  knee  and  thigh. 

4.  The  popliteal  glands. 

The  efferent  lymphatics  of  the  deep  femoral  glands  enter  the  abdo- 
minal cavity,  w'here  they  become  the  afferent  lymphatics  of  the 
external  iliac  glands. 

Blood-supply. — The  deep  femoral  glands  derive  their  arterial 
supply  from  the  superior  or  superficial  external  pudic  branch  of  the 
common  femoral  artery. 

Internal  or  Long  Saphenous  Vein. — This  vessel  arises  from  the 
inner  end  of  the  venous  arch  on  the  dorsum  of  the  foot.  It  passes 
in  front  of  the  internal  malleolus  and  along  the  inner  side  of  the  leg, 
where  it  lies  about  a  finger's  breadth  from  the  internal  border  of 
the  tibia.  It  then  courses  along  the  inner  side  of  the  knee-joint, 
being  situated  behind  the  most  prominent  part  of  the  internal 
condyle  of  the  femur,  and  so  it  enters  the  thigh.  Thereafter  it  ascends 
along  the  inner  side  of  the  thigh  superficial  to  the  sartorius,  until 
it  reaches  the  upper  third  of  that  division  of  the  limb.  Here  it 
turns  to  the  front  of  the  thigh,  and  in  its  subsequent  course  lies 
at  the  junction  of  the  inner  fourth  and  outer  three-fourths.  On 
reaching  a  point  i^  inches  below  Poupart's  ligament  it  pierces  the 
cribriform  fascia  and  anterior  wall  of  the  crural  sheath,  and 
terminates  in  the  femoral  vein.  Throughout  its  whole  course 
the  vein  is  superficial  to  the  deep  fascia.  It  receives  many 
tributaries  from  the  front  and  back  of  the  leg  and  thigh,  and  it 
communicates  at  frequent  intervals  with  the  venae  comites  of  the 
anterior  and  posterior  tibial  arteries,  these  communicating  branches 
being  intermuscular.  Two  tributaries  in  the  upper  part  of  the 
thigh  are  specially  noteworthy  from  their  size  and  constancy.  One, 
collecting  the  blood  from  the  front  of  the  thigh,  is  called  the  external 
femoral  cutaneous,  or  anterior  saphenous,  vein.  The  other  returns 
the  blood  from  the  inner  and  back  parts  of  the  thigh,  and  is  called 
the  internal  femoral  cutaneous,  or  posterior  saphenous,  vein.  These 
two   tributaries   terminate   in   the  long  saphenous  vein   near   the 


430  A  MANUAL  OF  ANATOMY 

saphenous  opening.  It  is  to  be  noted  that  the  external  femoral 
cutaneous  or  anterior  saphenous  vein  lies  over  the  sartorius  muscle 
at  the  apex  of  Scarpa's  triangle,  where  it  is  liable  to  be  cut  in 
operating  in  this  situation.  Before  piercing  the  cribriform  fascia 
the  internal  or  long  saphenous  vein  receives  as  final  tributaries  the 
following  veins  :  the  superficial  circumflex  iliac  ;  the  superficial 
epigastric ;  the  superior  or  superficial  external  pudic  ;  and  the 
inferior  or  deep  external  pudic.  The  long  saphenous  vein  has 
usually  about  fifteen  valves.  One  of  these  is  found  in  the  vein 
just  before  it  pierces  the  cribriform  fascia,  and  another  at  its 
opening  into  the  femoral  vein. 

The  guide  to  the  vein  in  the  femoral  part  of  its  course 
is  a  line  drawn  from  a  point  immediately  behind  the  most 
prominent  part  of  the  internal  condyle  of  the  femur  to  a  point 
on  the  front  of  the  thigh  ij  inches  below  Poupart's  ligament,  at 
the  junction  of  the  inner  fourth  and  outer  three-fourths  of  the 
limb. 

The  vein  is  occasionally  double  in  the  femoral  part  of  its 
course.  This  condition  is  brought  about  by  the  vein  dividing 
into  two  branches  shortly  after  it  enters  the  thigh,  which  ascend 
close  together  and  unite  to  form  one  trunk  close  to  the  saphenous 
opening. 

Deep  Fascia  or  Fascia  Lata. — The  fascia  lata  is  a  very  strong 
fibrous  membrane  which  forms  a  continuous  tubular  sheath  swathing 
the  powerful  muscles  in  this  region.  Superiorly  it  is  attached  as 
follows  :  (i)  to  Poupart's  ligament  as  far  inwards  as  the  pubic 
spine  ;  (2)  to  the  outer  lip  of  the  iliac  crest,  where  it  covers  the 
anterior  two- thirds  of  the  gluteus  medius  ;  (3)  to  the  posterior 
lamina  of  the  lumbar  aponeurosis  ;  (4)  to  the  back  of  the  lower  end 
of  the  sacrum  and  coccyx  ;  (5)  to  the  lower  border  of  the  great 
sacro-sciatic  ligament ;  (6)  to  the  tuber  ischii ;  (7)  to  the  ischio- 
pubic  ramus  ;  (8)  to  the  anterior  or  femoral  surface  of  the  body  of 
the  OS  pubis  close  to  the  symphysis  ;  and  (9)  to  the  anterior  lip  of 
the  pubic  crest  as  far  outwards  as  the  pubic  spine.  Inferiorly,  in 
the  region  of  the  knee,  the  fascia  lata  is  disposed  as  follows  :  (i)  on 
the  outer  side  it  is  attached  to  the  head  of  the  fibula  and  external 
tuberosity  of  the  tibia ;  (2)  anteriorly  it  is  attached  to  the  lateral 
borders  of  the  patella,  in  which  latter  situations  it  forms  the  larger 
portions  of  the  so-called  lateral  patellar  ligaments ;  from  its 
attachments  to  the  lateral  borders  of  the  patella  an  expansion  is 
sent  over  that  bone  and  downwards  to  the  head  of  the  tibia,  which 
confines  the  prepatellar  bursa  ;  (3)  posteriorly  it  is  continued  un- 
interruptedly into  the  back  of  the  leg,  covering  the  popliteal  space 
as  it  descends,  and  becoming  continuous  with  the  deep  fascia ; 
(4)  internally  it  is  continued  into  the  inner  side  of  the  leg,  taking 
a  limited  attachment  to  the  internal  tuberosity  of  the  tibia,  and 
becoming  continuous  with  the  deep  fascia. 

The  fibres  of  the  fascia  lata  interlace  freely,  some  of  them 
being  circular  and  others  longitudinal.     It  is  pierced  by  a  large 


THE  LOWER  LIMB 


431 


number  of  minute  foramina  for  the 
passage  of  bloodvessels  and  nerves. 
The  fascia  is  strongest  upon  the 
outer  side  of  the  thigh,  where  it 
gives  insertion  superiorly  to  a  large 
part  of  the  gluteus  maximus,  and 
lower  down  to  the  tensor  fasciae 
femoris.  It  is  also  strong  over  the 
popliteal  space  and  prepatellar  region, 
receiving  in  the  former  situation 
accessions  of  fibres  from  the  ham- 
string tendons,  and,  in  the  latter, 
similar  accessions  from  the  tendons  of 
the  muscles  which  form  the  quadri- 
ceps extensor  cruris.  Upon  the  inner 
side  of  the  thigh  the  fascia  is  very 
thin. 

The  portion  upon  the  outer  side  of 
the  thigh,  between  the  fore  part  of 
the  iliac  crest  and  the  anterior  part 
of  the  external  tuberosity  of  the  tibia 
and  outer  border  of  the  patella,  is 
spoken  of  as  the  ilio-tibial  band.  At 
the  insertion  of  the  tensor  fascise 
femoris  it  gives  off  a  deep  lamina 
which  passes  upwards  on  the  deep  sur- 
face of  the  muscle  to  be  attached  to  the 
bottom  of  the  groove  on  the  dorsum 
of  the  ilium  above  the  acetabulum, 
where  the  posterior  or  reflected  head 
of  the  rectus  femoris  takes  its  origin. 
This  deep  lamina  is  intimately  con- 
nected with  the  capsular  ligament  of 
the  hip-joint  and  the  tendon  of  the 
gluteus  minimus. 

The  fascia  lata  on  the  front  of  the 
thigh  divides  at  a  point  i^  inches 
below  the  inner  third  of  Poupart's 
ligament  into  two  lamina,  iliac  and 
pubic.  The  iliac  lamina  j)asses  up- 
wards to  be  attached  to  Poupart's 
ligament,  lying  superficial  to  the  outer 
portion  of  the  anterior  wall  of  the 
crural  sheath.  The  pubic  lamina  is 
on  a  deeper  or  more  posterior  plane 
than  the  iliac,  and  passes  upwards 
upon  the  flat  j)ectineus  muscle  to 
be  attached  to  the  pectineal  portion 
of  the  ilio-jjectineal  liii'-  and  anterior 


Fig.    221. — The    Internal 

Saphenous    Vein    and    its 

Tkibutakies. 


432  A   MANUAL  OF  ANATOMY 

lip  of  the  pubic  crest.  This  pubic  lamina,  when  followed  out- 
wards, passes  behind  the  crural  sheath  and  ends  by  blending  with 
its  posterior  wall.  It  will  thus  be  seen  that  the  iliac  lamina  is 
superficial  or  anterior  to  the  femoral  vessels  enclosed  in  the  crural 
sheath,  and  that  the  pubic  lamina  is  on  a  plane  deeper  than,  or 
posterior  to,  the  femoral  vessels. 

Processes  of  the  Fascia  Lata. — ^These  processes,  which  for  the  most 
part  are  indicated  on  the  surface  by  white  lines,  pass  between  the 
muscles,  forming  intermuscular  septa,  and  taking  part  in  the 
muscular  sheaths.  Three  of  them  are  specially  noteworthy,  and 
are  called  external,  internal,  and  posterior.  The  external  inter- 
muscular septum  is  a  deep  expansion  from  the  ilio- tibial  band, 
and  it  is  attached  to  the  outer  lip  of  the  linea  aspera  and 
external  supracondylar  ridge  of  the  femur  in  its  whole  extent. 
It  separates  the  vastus  externus  and  crureus  in  front  from  the 
femoral  head  of  the  biceps  behind,  and  it  gives  partial  origin 
to  these  muscles.  The  internal  intermuscular  septum  is  a  delicate 
process,  which  is  attached  to  the  inner  lip  of  the  linea  aspera, 
especially  in  its  lower  part.  Over  the  internal  supracondylar  ridge 
its  place  is  taken  by  an  expansion  from  the  tendon  of  the  adductor 
magnus.  This  septum  separates  the  vastus  internus  in  front  from 
the  adductor  longus  and  adductor  magnus  behind.  The  posterior 
intermuscular  septum  is  a  very  delicate  process  which  is  attached 
to  the  summit  of  the  linea  aspera.  It  is  situated  behind  the 
adductor  magnus,  which  it  separates  from  the  femoral  head  of  the 
biceps. 

Saphenous  Opening. — This  is  an  opening  in  the  fascia  lata  for 
the  passage  of  the  long  saphenous  vein,  and  it  is  of  importance 
surgically  inasmuch  as  a  femoral  hernia  may  protrude  through 
it.  It  is  situated  on  the  front  of  the  thigh  below  and  outside 
the  pubic  spine,  just  below  the  inner  third  of  Poupart's  liga- 
ment. It  is  not  so  much  an  opening  as  an  oval  depression  in 
the  fascia  lata,  formed  by  the  division  of  that  fascia  into  its  iliac 
and  pubic  laminse,  the  iliac  lamina  passing  upwards  superficial  to 
the  outer  part  of  the  anterior  wall  of  the  crural  sheath,  and  the  pubic 
lamina  passing  upwards  on  a  plane  posterior  to  the  posterior  wall 
of  the  crural  sheath,  with  which  it  becomes  continuous.  The 
average  length  of  the  opening  is  i^  inches,  and  its  breadth  is  from 
■|-  to  f  inch.  The  lower  border  of  the  opening  is  called  the  inferior 
€Ornu,  and  over  this  the  long  saphenous  vein  passes.  It  is  firm, 
sharp,  and  crescentic,  with  the  concavity  directed  upwards.  The 
inner  part,  formed  by  the  pubic  lamina  of  the  fascia  lata,  is  for  the 
most  part  fiat,  the  fascia  being  here  spread  out  upon  the  pectineus 
muscle,  whence  it  passes  outwards  to  blend  with  the  posterior  wall 
of  the  crural  sheath.  Over  the  lower  fourth,  however,  the  opening 
has  a  distinct  inner  border,  which  is  continuous  with  the  inferior 
cornu.  The  outer  border,  formed  by  the  iliac  lamina  of  the  fascia 
lata,  is  on  a  plane  superficial  to  the  outer  part  of  the  anterior  wall 
of  the  crural  sheath,  to  which  it  is  bound  by  fibrous  bands.     In- 


THE  LOWER  LIMB 


433 


feriorly  this  border  is  continuous  with  the  inferior  cornu.  Superiorly 
it  curves  inwards  over  the  anterior  wall  of  the  crural  sheath.  The 
whole  border  is  concave  or  semilunar,  the  concavity  being  directed 
inwards  and  slightly  downwards.  The  upper  border  is  the  portion 
in  front  of  the  anterior  wall  of  the  crural  sheath,  and  it  lies  immedi- 
ately below  Poupart's  ligament.     It  is  called  the  superior  cornu. 

Superficial  Circumflex  Iliac  Art' 
Superficial  Circumflex  II 

Superficial  Epigastric  \  c^>,p1 

Femoral  Vein 

Falciform  Process  of  Burns     ^  \V 
and  Superior  Cornu        ^ 

Internal  Saphenous  Veniv 

Superior  External  Pudic  Ve: 


Inferior  Cornu  of  Saphenous  Opening- 
Posterior  Saphenous  Vein  — 
Anterior  Saphenous  Vein  _ 


Internal  Saphenous  Veil 
(In  this  case  double) 


Fig.  222. — The  Left  Internal  Saphenous  Vein  in  the  Thigh,  with  its 
Tributaries,  and  the  Saphenous  Opening. 

It  is  triangular,  and  is  continuous  with  the  outer  border.  Superiorly 
it  is  attached  to  the  inner  part  of  Poupart's  ligament,  extending 
inwards  as  far  as  the  pubic  spine,  and  a  few  of  its  fibres  join  the 
antero-inf(;rior  or  femoral  surface  of  Giml:)ernat's  ligament.  The 
inner  portion  of  the  superior  cornu  is  internal  to  the  femoral  vein, 
and  lies  in  front  of  the  crural  canal.     It  is  this  portion,  inside  the 

28 


434  A   MANUAL  OF  ANATOMY 

femoral  vein,  which  has  been  called  the  falciform  process  of  Burns 
(John),*  or  the  femoral  ligament  of  Hey.  The  importance  of  this 
process  or  ligament  is  that  it  impresses  upon  a  femoral  hernia  its 
final  change  in  direction,  inasmuch  as  it  causes  the  protrusion  to 
turn  upwards  over  Poupart's  ligament  upon  the  anterior  abdominal 
wall,  or  upwards  and  outwards  towards  the  anterior  superior  iliac 
spine. 

The  saphenous  opening  is  covered  by  the  cribriform  fascia,  which 
is  more  intimately  attached  to  the  outer  border  than  elsewhere. 

Parts  concerned  in  Femoral  Hernia. 

Poupart's  Ligament  or  the  Superficial  Crural  Arcli. — This  is  the 
thickened  lower  border  of  the  aponeurosis  of  the  external  oblique 
muscle.  It  is  folded  upon  itself  in  a  backward  direction,  and  is 
attached  externally  to  the  anterior  superior  iliac  spine  and  internally 
to  the  pubic  spine. 

Gimbernat's  Ligament. — This  is  the  reflection  of  Poupart's 
ligament  from  the  pubic  spine  along  the  ilio-pectineal  line  for  i  inch. 
It  is  triangular,  and  presents  a  free  base  which  is  sharp,  wiry,  and 
concave,  and  is  situated  immediately  to  the  inner  side  of  the  crural 
or  femoral  ring. 

Deep  Crural  Arch. — This  is  a  thickening  of  the  fascia  trans- 
versalis,  due  to  an  accession  of  fibres  as  it  is  prolonged  downwards 
beneath  Poupart's  ligament.  It  extends  from  the  centre  of  that 
ligament  on  its  deep  aspect  to  the  pectineal  portion  of  the  ilio- 
pectineal  line,  where  it  is  attached  behind  Gimbernat's  ligament 
near  its  base. 

Falciform  Process  of  Burns. — This  has  just  been  described  in 
connection  with  the  superior  cornu  of  the  saphenous  opening. 

Crural  or  Femoral  Sheath. — This  sheath  extends  from  Poupart's 
ligament  to  a  point  about  i^  inches  below  it,  where  it  blends  with 
the  special  sheath  of  the  femoral  vessels.  The  outer  wall  is  straight, 
but  the  inner  is  oblique,  being  sloped  downwards  and  outwards. 
In  shape  the  sheath  resembles  a  funnel,  from  which  circumstance 
the  term  infundihuliform  has  been  applied  to  it.  The  anterior  wall 
is  formed  by  the  fascia  transversalis,  and  the  posterior  wall  by  the 
fascia  iliaca,  both  of  which  fasciae  are  prolonged  downwards  beneath 
Poupart's  ligament.  The  outer  wall  is  formed  by  the  union  of  these 
two  fasciae  close  to  the  outer  side  of  the  femoral  artery.  The 
inner  wall  is  formed  by  their  union  at  a  point  J  inch  to  the  inner 
side  of  the  femoral  vein. 

Within  the  sheath  there  are  two  septa,  external  and  internal,  both 
of  which  extend  from  the  anterior  to  the  posterior  wall,  the  external 
septum  being  close  to  the  outer  side  of  the  femoral  vein,  and  the 
internal  septum  close  to  its  inner  side.  By  means  of  these  two  septa 
the  interior  of  the  sheath  is  divided  into  three  distinct  compart- 

*  Edinburgh  Medical  and  Surgical  Journal,  July  i,  1806,  p.  269. 


THE  LOWER  LIMB  435 

ments — outer,  middle,  and  inner.  The  outer  compartment  contains 
the  common  femoral  artery  and  the  crural  branch  of  the  genito- 
crural  nerve  for  a  short  distance  at  its  upper  part,  where  the 
nerve  lies  immediately  external  to  the  artery.  The  middle  com- 
partment contains  the  femoral  vein  and  three  of  the  deep  femoral 
glands.  The  inner  compartment  is  called  the  crural  or  femoral 
canal,  and  it  contains  one  of  the  deep  femoral  glands  and  a  certain 
amount  of  adipose  tissue,  the  gland  lying  at  the  upper  end  of  the 
canal. 

Crural  or  Femoral  Canal. — This  is  the  inner  compartment  of 
the  crural  sheath,  and  it  is  ^  inch  in  length.  Its  upper  end  forms 
the  crural  or  femoral  ring,  and  is  on  a  level  with  the  base  of  Gim- 
bernat's  ligament.  Its  lower  end  is  just  below  the  superior  cornu 
of  the  saphenous  opening.  The  boundaries  of  the  canal  are  as 
follows  :  the  anterior  wall  is  formed  by  the  fascia  transversalis  ;  the 
posterior  wall  by  the  fascia  iliaca  ;  the  inner  wall  by  the  junction  of 
the  fascia  transversalis  and  fascia  iliaca  ;  and  the  outer  wall  by  the 
internal  septum  within  the  sheath. 

Crural  or  Femoral  Ring. — This  is  by  no  means  a  patent 
opening,  but  is  bridged  over  by  the  subperitoneal  areolar  tissue 
of  the  abdominal  wall.  The  septum  thus  formed  between  the 
crural  canal  and  abdominal  cavity  is  called  the  septum  crurale 
(fascia  of  Cloquet).  It  protrudes  slightly  into  the  canal,  and  the 
l^TTiphatic  gland  which  lies  at  the  upper  end  of  the  canal  is  attached 
to  its  under  convex  surface.  When  the  septum  crurale  has  been 
removed  from  the  crural  ring,  the  aperture  presents  an  oval 
shape,  with  the  long  measurement  lying  transversely,  in  which 
direction  it  measures  |  inch.  It  readily  admits  the  little  finger, 
and  it  is  somewhat  larger  in  the  female  than  in  the  male.  The 
situation  of  the  ring  is  close  to  the  outer  side  of  the  base  of 
Gimbernat's  ligament,  and  its  position  may  be  ascertained  in  one 
of  two  ways. 

(i)  Draw  a  line  from  the  pubic  spine  horizontally  outwards  across 
the  front  of  the  thigh,  and  take  a  point  in  this  line  fully  i  inch  to  the 
outer  side  of  the  pubic  spine. 

(2)  Find  the  central  point  between  the  anterior  superior  iliac 
spine  and  the  symphysis  pubis  ;  then  take  a  point  on  Poupart's 
ligament  rather  more  than  ^  inch  to  the  inner  side  of  this  central 
point. 

Boundaries— ^M^mor. — The  inner  part  of  Poupart's  ligament, 
and  the  deep  crural  arch.  Posterior. — The  pubic  lamina  of  the 
fascia  lata,  joined  by  Cooper's  ligament  ;*  the  pectineus  muscle  ; 
and  the  superior  pubic  ramus.     Internal. — The  base  of  Gimbernat's 

*  The  pubic  ligament  of  Cooper  is  a  strong  bundle  of  fibres  extending 
between  the  iho-]jectineal  eiiii  icnce  and  the  pubic  spine,  between  which 
points  it  is  attaclied  to  the  pectineal  portion  of  the  ilio-pectincal  line.  It 
has  the  pectineal  border  of  Gimbernat's  ligament  immediately  behind  it, 
and  is  closely  incorporated  with  the  pubic  lamina  of  the  fascia  lata,  where 
that  is  attached  to  the  pectineal  portion  of  the  ilio-pectineal  line. 

28—2 


436  A   MANUAL  OF  ANATOMY 

ligament.  External. — ^The  upper  extremity  of  the  internal  septum 
within  the  crural  sheath. 

Normal  Relation  of  Bloodvessels  to  the  Crural  Ring — Anterior. — 
The  pubic  branch  of  the  deep  epigastric  artery,  as  it  courses 
inwards  behind  the  inner  half  of  Poupart's  ligament.  Super o- 
anterior. — ^The  vessels  of  the  spermatic  cord  in  the  male,  or  of  the 
round  ligament  of  the  uterus  in  the  female.  Sup ero- external. — The 
deep  epigastric  vessels.  External. — ^The  femoral  vein,  becoming 
the  external  iliac  vein,  and  separated  from  the  ring  by  the  upper 
extremity  of  the  internal  septum  within  the  crural  sheath. 

There  are  normally  no  vessels  behind  the  ring,  nor  internal  to 
it.  Under  no  circumstances  are  there  ever  any  vessels  behind  it, 
but  in  certain  cases  there  may  be  a  vessel  on  its  inner  side,  namely, 
an  abnormal  obturator  artery. 

Abnormal  or  Aberrant  Obturator  Artery. — The  obturator  artery  normally 
arises  from  the  anterior  division  of  the  internal  iliac,  and  under  these  circum- 
stances it  has  no  relation  to  the  crural  ring.  In  about  30  per  cent,  of  cases, 
however,  the  obturator  arises  from  the  deep  epigastric  artery  near  its  com- 
mencement. This  origin  is  more  common  in  the  female  than  in  the  male, 
and  is  rarely  bilateral.  In  most  of  these  cases  the  aberrant  obturator  passes 
backwards  close  to  the  inner  side  of  the  commencement  of  the  external  iliac 
vein,  and  therefore  upon  the  outer  side  of  the  crural  ring.  In  a  few  cases 
the  aberrant  vessel  passes  backwards  across  the  centre  of  the  crural  ring. 
In  very  rare  cases  it  passes  inwards  behind  Poupart's  ligament,  and  then 
arches  backwards  either  close  to  the  base  of  Gimbernat's  ligament,  or  a  line 
or  two  inwards  from  it,  and  therefore  upon  the  inner  side  of  the  crural  ring. 
If  a  femoral  hernia  should  occur  under  these  latter  circumstances,  the  aberrant 
obturator  artery  would  lie  upon  the  inner  side  of  the  neck  of  the  sac,  and  it 
would  thus  be  endangered  in  the  operation  for  the  relief  of  the  strangulation. 
This  very  rare  position  of  an  aberrant  obturator  artery  is  more  frequent  in 
the  male  than  in  the  female,  and,  according  to  Lawrence,  it  occurred  once  in  a 
hundred  cases. 

The  origin  of  an  aberrant  obturator  artery  from  the  deep  epigastric  is  due 
to  a  more  or  less  complete  obliteration  of  a  normal  obturator  at  its  origin, 
and  an  enlargement  of  the  normal  anastomosis  which  takes  place  between 
the  pubic  branches  of  the  deep  epigastric  and  obturator  arteries  behind  the 
body  of  the  os  pubis. 

Femoral  Hernia. — This  is  a  protrusion  of  an  abdominal  viscus,  or  part  of  a 
viscus,  through  the  crural  or  femoral  ring.  The  course  of  the  hernia  is  as 
follows  :  entering  the  crural  ring  by  elongating  the  septum  crurale,  it  descends 
through  the  crural  canal,  on  reaching  the  lower  end  of  which  it  is  placed  in 
the  upper  part  of  the  saphenous  opening,  immediately  below  the  falciform 
process  of  Burns  or  femoral  ligament  of  Hey.  This  structure  now 
impresses  upon  the  hernia  the  following  change  in  its  course :  the  front 
part  of  the  hernia  being  arrested  in  its  downward  course  by  that  structure, 
the  posterior  part,  which  is  free,  comes  down,  and,  passing  forwards,  turns 
upwards  upon  the  anterior  abdominal  wall,  or  upwards  and  outwards 
along  Poupart's  ligament.  The  course  of  a  femoral  hernia,  when  com- 
plete, is  thus  at  first  downwards  through  the  crural  ring  and  crural  canal, 
then  forwards  through  the  upper  part  of  the  saphenous  opening,  and  finally 
either  upwards  or  upwards  and  outwards. 

Coverings  of  a  Femoral  Hernia. — The  coverings,  from  within  outwards,  are 
as  follows  : 

1.  Peritoneum,  which  forms  the  sac. 

2.  Septum  crurale. 


Deep  Circumflex  Iliac  Artery 
Internal  Abdominal  Ring  j 


Deep  Epiga'itric  Artery 


External  Iliac  Vein 


Gimbernat's  Ligament 


Abnormal  Obturator 
Artery 


-External  Iliac  Artery 


I  Obturator  Nerve 

Obturator  Canal 


Fig.  222A. — Diagrams  of  Abnormal  Obturator  Artery. 
(The  red  X  indicates  the  position  of  the  Crural  or  Femoral  Ring). 

[A  and  B  after  Gray]. 

A,  Artery  external  to  Crural  Ring  ;   B,  Artery  internal  to  Ring,  and  close  to 

Base  of  Gimbernat's  Ligament ;   C,  Artery  internal  to  Ring,  and  one  or  two 

lines  from  Base  of  Gimbernat's  Ligament. 


[To /ace  page  436. 


THE  LOWER  LIMB  437 

3.  Anterior  wall  of  the  crural  sheath,  or  fascia  transversalis. 

4.  Cribriform  fascia. 

5.  Subcutaneous  layer  of  superficial  fascia. 

6.  Skin. 

The  septum  crurale  is  usually  inseparably  united  with  the  anterior  wall 
of  the  crural  sheath,  thus  forming  the  fascia  propria  of  Cooper.  The  neck 
of  the  sac  is  on  a  level  with  the  base  of  Gimbernat's  ligament,  which  is  the  most 
common  cause  of  strangulation. 

Prepatellar  Bursa. — This  bursa,  which  is  of  large  size,  is  situated 
on  the  anterior  surface  of  the  patella,  beneath  a  fascial  expansion 
derived  from  the  fascia  lata  along  its  attachments  to  the  lateral 
borders  of  the  bone.  When  it  becomes  inflamed  the  condition  is 
known  as  housemaid' s  knee. 

Anterior  Femoral  Muscles.  Sartorius — Origin. — (i)  The  anterior 
superior  iliac  spine,  and  (2)  the  upper  part  of  the  anterior  inter- 
spinous  notch  of  the  ilium. 

Insertion. — The  internal  surface  of  the  shaft  of  the  tibia  immedi- 
ately behind  the  tubercle.  From  the  tendon  of  insertion  two 
expansions  are  given  off— one  from  the  upper  border  to  the 
capsule  of  the  knee-joint,  and  another  from  the  lower  border  to 
the  deep  fascia  of  the  leg. 

Nerve-supply. — The  anterior  division  of  the  anterior  crural  nerve, 
the  branches  from  which,  arising  in  common  with  the  middle 
cutaneous  nerve,  enter  the  muscle  near  the  apex  of  Scarpa's  triangle. 

Action. — Acting  from  its  origin  the  muscle  is  (i)  a  flexor  of  the 
knee-joint,  and  an  internal  rotator  of  the  leg  ;  and  (2)  a  flexor  of 
the  hip-joint,  and  an  external  rotator  and  abductor  of  the  thigh. 
Acting  from  its  insertion  it  is  a  flexor  of  the  pelvis  upon  the  thigh. 

The  sartorius  is  a  long  ribbon-like  muscle,  the  fascicuh  of  which 
are  the  longest  of  any  muscle  in  the  body.  The  rnuscle,  therefore, 
has  a  wide  range  of  movement,  but  comparatively  little  power. 
It  is  at  first  directed  downwards  and  inwards  over  the  front  of  the 
thigh,  where  it  forms,  by  its  inner  border,  the  outer  boundary  of 
Scarpa's  triangle.  Having  crossed  the  superficial  femoral  artery 
at  a  point  about  3^  inches  below  Poupart's  ligament,  the  muscle 
passes  vertically  downwards  as  far  as  the  internal  condyle  of  the 
femur.  Beyond  this  point,  it  curves  forwards  to  its  insertion, 
where  it  covers  the  subjacent  tendons  of  the  gracilis  and  semi- 
tendinosus,  from  which  it  is  separated  by  a  bursa.  This  bursa  is  a 
prolongation  of  that  which  lies  between  the  internal  lateral  ligament 
of  the  knee-joint  and  the  more  superficially  placed  tendons  of  the 
gracilis  and  semitendinosus.  The  muscle,  in  its  lower  part,  is  usually 
pierced  by  the  patellar  branch  of  the  long  saphenous  nerve. 

The  two  most  important  relations  of  the  sartorius  are  as  follows  : 
(i)  it  crosses  the  sujjcrficial  femoral  artery  from  without  inwards 
at  a  jKjint  about  3i  inches  below  Poupart's  ligament  ;  and  (2)  it 
covers  the  superficial  femoral  artery  in  Hunter's  canal. 

Tensor  Fasciae  Femoris.— Akh(jugh  this  muscle  is  on  the  same 
plane  as  the  gluteus  maximus,  it  may  be  described  in  this  place. 


438  A   MANUAL  OF  ANATOMY 

Origin. — (i)  The  outer  lip  of  the  crest  of  the  ihum  for  i|  inches 
at  its  anterior  part ;  (2)  the  dorsum  iHi  for  J  inch  close  to  the 
upper  part  of  the  anterior  interspinous  notch  ;  and  (3)  the  fascia 
lata  covering  the  muscle. 

Insertion. — ^The  angle  of  division  of  the  ilio-tibial  band  of  the 
fascia  lata  into  a  superficial  and  deep  lamina,  at  the  junction  of  the 
upper  fourth  and  lower  three-fourths  of  the  thigh. 

Nerve- supply. — The  lower  division  of  the  superior  gluteal  nerve 
from  the  sacral  plexus,  the  branch  of  which  enters  the  muscle  on 
its  deep  surface. 

Action. — (i)  Abductor  and  internal  rotator  of  the  thigh  ;  and 
(2)  extensor  of  the  knee-joint.  The  muscle,  in  association  with 
the  gluteus  maximus,  takes  part  in  the  completion  of  extension  of 
the  knee-joint,  and  in  the  maintenance  of  extension  through  means 
of  the  ilio-tibial  band,  as  in  standing. 

The  tensor  fasciee  femoris  is  a  fiat,  strap-like  muscle,  the  direc- 
tion of  which  is  downwards,  with  a  slight  inclination  outwards 
and  backwards. 

Ilio-Psoas. — The  femoral  portion  of  this  muscle  is  alone  described 
in  this  place.  For  a  full  description  of  the  psoas  magnus  and 
iliacus,  see  Abdomen  Section.  The  ilio-psoas  is  inserted  into  the 
small  trochanter  of  the  femur,  the  outer  fibres  of  the  iliacus  taking 
insertion  into  the  triangular  surface  which  is  situated  below  and  in 
front  of  the  small  trochanter,  between  it  and  the  spiral  line. 

The  outer  portion  of  the  muscle,  which  is  fleshy,  represents  the 
iliacus,  and  the  inner  portion,  which  is  tendinous,  represents  the 
psoas  magnus.  Lying  deeply  between  the  two  is  the  anterior 
crural  nerve  ;  the  femoral  artery,  enclosed  within  the  crural  sheath, 
rests  upon  the  psoas  magnus  ;  and  the  femoral  vein,  similarly 
enclosed,  lies  between  the  psoas  magnus  and  pectineus.  The  ilio- 
psoas covers  the  front  of  the  capsular  ligament  of  the  hip- joint, 
a  bursa  intervening  between  the  psoas  portion  and  the  ligament. 

Pectineus — Origin. — (i)  The  pectineal  portion  of  the  ilio-pectineal 
line  of  the  os  pubis  ;  (2)  the  adjacent  portion  of  the  upper  or  pec- 
tineal surface  of  the  superior  pubic  ramus  ;  and  (3)  the  pubic 
lamina  of  the  fascia  lata,  as  it  covers  the  muscle  in  this  situation. 

Insertion. — The  upper  third  of  the  line  which  leads  from  the  back 
of  the  small  trochanter  of  the  femur  to  the  inner  lip  of  the  linea 
aspera. 

Nerve-supply. — The  anterior  division  of  the  anterior  crural  nerve, 
the  branch  from  which  passes  inwards  behind  the  crural  sheath,  and 
enters  the  superficial  surface  of  the  muscle  close  to  its  outer  border. 
The  pectineus  sometimes  receives  an  additional  nerve  from  the 
anterior  division  of  the  obturator,  or  from  the  accessory  obturator 
(when  present),  which  enters  the  deep  surface  of  the  muscle. 

Action. — (i)  Flexion  of  the  hip- joint,  and  (2)  adduction  and 
external  rotation  of  the  thigh,  as,  for  example,  in  crossing  one  leg 
over  the  other. 

The  pectineus  is  a  flat,  four-sided  muscle,  which  is  directed  down- 


THE  LOWER  LIMB 


439 


wards,  outwards,  and  backwards.  The  surfaces  at  first  look 
forwards  and  backwards,  but,  towards  its  insertion,  the  muscle 
undergoes  a  slight  twist,  and  its  surfaces  are  then  external  and 
internal.  Its  deep  surface  is  related  to  the  capsular  ligament  of 
the  hip-joint,  the  anterior  division  of  the  obturator  nerve,  and  the 
adductor  brevis. 

Quadriceps  Extensor  Cruris.— This  is  a  composite  muscle,  which 
consists  of  the  rectus  femoris,  vastus  externus,  crureus,  and  vastus 
internus.     The   rectus   femoris   arises   from   the   os   innominatum, 


5"i'ii"|'"f''aM 


Quadratus  Luniborum 


Pyriformis 


Twelfth-Rib 


Psoas  Parvus 


Psoas  Magnus 


Iliacus 


Small  Sacro-sciatic 
Lisrament 


. Great  Sacro-sciatic 

Ligament 


Obturator  Externus 

Fig.  223. — The  Psoas,  Iliacus,  and  Quadratus  I.umborum  Muscles. 

whilst  the  other  three  muscles  take  origin  from  the  femur,  the  crureus 
being  situated  between  the  vastus  externus  and  vastus  internus. 

I.  Rectus  Femoris — Origin. — By  two  strong  tendinous  heads — 
anterior  or  straight,  and  posterior  or  reflected.  The  anterior  or 
straight  head  arises  from  the  anterior  inferior  iliac  spine.  The 
posterior  or  reflected  head  arises  from  the  groove  on  the  anterior 
jjart  of  the  dorsum  ilii  immediately  above  the  brim  of  the  aceta- 
bulum, where  it  is  under  cover  of  the  gluteus  minimus.  The  two 
heads  unite  at  an  angle  of  about  50  degrees. 


440  A  MANUAL  OF  ANATOMY 

Insertion. — The  anterior  part  of  the  upper  border  of  the  patella 
by  a  fiat  tendon,  which  is  free  from  fleshy  fibres  in  its  lower 
3  inches. 

Nerve-supply. — The  posterior  division  of  the  anterior  crural  nerve, 
the  branch  from  which  furnishes  an  offset  to  the  hip-joint. 

Action. — (i)  The  muscle  is  a  powerful  extensor  of  the  knee-joint ; 
and  (2)  it  is  a  flexor  of  the  hip-joint.  In  extending  the  knee-joint 
the  rectus  femoris  acts  entirely  from  its  anterior  or  straight  head 
when  the  hip- joint  is  extended  ;  but,  when  the  hip- joint  is  flexed, 
the  muscle  in  extending  the  knee-joint  acts  from  its  posterior  or 
reflected  head. 

The  fibres  which  form  the  fleshy  belly  are  very  short,  and,  spring- 
ing in  a  bipenniform  manner  from  the  common  tendon  of  origin, 
they  pass  obliquely  to  end  upon  the  tendon  of  insertion  as  low 
as  a  point  3  inches  above  the  patella.  This  arrangement  gives  the 
muscle  great  power  of  action,  but  limited  range  of  movement. 
Superiorly  the  muscle  is  related  to  the  capsular  ligament  of  the 
hip- joint. 

2.  Vastus  Externus — Origin. — (i)  The  upper  third  of  the  anterior 
intertrochanteric  line  of  the  femur  ;  (2)  the  anterior  and  inferior 
borders  of  the  great  trochanter  ;  (3)  the  outer  side  of  the  gluteal 
ridge  ;  (4)  the  outer  lip  of  the  linea  aspera  in  its  upper  half  ;  (5)  the 
adjacent  portion  of  the  shaft  of  the  femur  ;  and  (6)  the  upper  part 
of  the  external  intermuscular  septum. 

Insertion. — (i)  The  outer  half  of  the  upper  border  of  the  patella 
posterior  to  the  rectus  femoris  ;  (2)  the  upper  third  of  the  outer 
border  of  the  patella  ;  and  (3)  very  slightly  into  the  outer  border 
of  the  tendon  of  the  rectus  femoris. 

Nerve-supply. — The  posterior  division  of  the  anterior  crural 
nerve,  the  branch  from  which  furnishes  an  offset  to  the  knee-joint. 

The  vastus  externus  at  its  origin  is  aponeurotic,  and  the  aponeurosis 
spreads  downwards  upon  the  superficial  surface  of  the  muscle 
for  a  considerable  distance.  The  fibres  are  directed  downwards  and 
forwards  or  inwards.     The  anterior  border  is  free. 

3.  Crureus — Origin. — (i)  The  lower  two-thirds  of  the  anterior 
intertrochanteric  line  ;  (2)  the  anterior  and  external  surfaces  of  the 
shaft  of  the  femur  over  about  their  upper  three-fourths ;  (3)  the 
outer  lip  of  the  linea  aspera  in  its  lower  half  ;  (4)  the  upper  two- 
thirds  of  the  external  supracondylar  ridge,  as  well  as  the  immediately 
adjacent  portion  of  the  bone  ;  and  (5)  the  contiguous  part  of  the 
external  intermuscular  septum. 

Insertion. — The  inner  half  of  the  upper  border  of  the  patella 
behind  the  rectus  femoris,  where  it  has  many  of  the  fibres  of  the 
vastus  internus  associated  with  it. 

Nerve-supply. — The  posterior  division  of  the  anterior  crural 
nerve,  the  branches  from  which  are  two  or  three  in  number.  The 
most  internal  of  these  branches  furnishes  an  offset  to  the  knee- 
joint,  which  in  its  course  supplies  the  subcrureus  muscle. 

The  direction  of  the  fibres  of  the  crureus  is  chiefly  downwards, 


THE  LOWER  LIMB 


441 


except  in  the  lower  and  outer  part  of  the  muscle,  where  they  pass 
forwards. 

4.  Vastus  Internus — Origin. — (i)  The  part  of  the  spiral  line  of  the 
femur  which  extends  from  the  inferior  cervical  tubercle  to  the  inner 


Ligamentum  Teres 

Capsular  Ligament 

Ilio-Psoas \y-  Ik]     '    j'L'm Anterior  Intertrochanteric  Line 


Crureus, 

Bare  Area  of  Femur_ 
Vastus  Internus.- 


_1 Vastus  Externus 


Tendon  of  Rectus  Femoris 


Fig.  224. — Dissection  of  the  Quadriceps  Extensor 
Cruris  Muscle. 

lip  of  the  linea  aspera  ;  (2)  the  inner  lip  of  the  linea  aspera  in  its 
whole  extent ;  (3)  the  internal  intermuscular  septum  ;  and  (4)  the 
front  of  the  tendon  of  the  addvictor  magnus  ahnost  as  low  as  the 
adductor  tubercle. 

Insertion. — (i)  The  inner  half  of  the  ujjper  border  of  the  patella, 


442  A   MANUAL  OF  ANATOMY 

in  close  association  with  the  crureus  ;  (2)  the  upper  half  of  the  inner 
border  of  the  patella  ;  and  (3)  very  slightly  into  the  inner  border  of 
the  tendon  of  the  rectus  femoris. 

Nerve-supply. — ^The  posterior  division  of  the  anterior  crural  nerve 
by  a  branch  called  the  nerve  to  the  vastus  internus.  This  nerve 
descends  in  close  contact  with,  and  on  the  outer  side  of,  the  long 
saphenous  nerve,  and  with  that  nerve  it  traverses  the  upper  half 
of  Hunter's  canal.     It  furnishes  a  large  offset  to  the  knee-joint. 

The  direction  of  the  fibres  of  the  muscle  is  downwards  and  for- 
wards or  outwards. 

Whilst  the  vastus  externus  is  easily  separable  from  the  crureus, 
the  vastus  internus  and  crureus  appear  at  first  sight  to  be  one 
muscle.  A  cellular  interval,  however,  can  be  traced  directly 
upwards  from  the  inner  border  of  the  patella  to  the  inferior  cervical 
tubercle  of  the  femur,  along  the  course  of  which  the  two  muscles  can 
be  distinctly  separated.  When  this  separation  has  been  effected, 
a  characteristic  elongated  strip  of  the  femur  is  laid  bare  upon  the 
inner  side  of  the  shaft,  which  is  free  from  muscular  fibres. 

Suprapatellar  Tendon. — This  is  the  common  tendon  in  which  the 
four  muscles  constituting  the  quadriceps  extensor  cruris  terminate. 
The  part  of  it  which  belongs  to  the  rectus  femoris  is  inserted  into  the 
anterior  part  of  the  upper  border  of  the  patella,  whence  an  expansion 
of  fibres  descends  over  the  front  of  that  bone  to  blend  with  the  fibres 
of  the  ligamentum  patellae.  The  tendon  of  the  crureus  is  behind 
that  of  the  rectus  femoris,  where  it  has  many  of  the  fibres  of  the 
vastus  internus  associated  with  it,  the  rest  of  the  last-named  muscle 
terminating  partly  upon  the  upper  half  of  the  inner  border  of  the 
patella,  and  partly  upon  the  inner  border  of  the  tendon  of  the  rectus 
femoris.  The  vastus  externus  is  partly  behind  the  rectus  tendon, 
and  in  part  it  joins  the  outer  border  of  that  tendon,  and  terminates 
upon  the  upper  third  of  the  outer  border  of  the  patella.  Beneath 
the  suprapatellar  tendon  there  is  a  bursa,  called  the  suprapatellar 
bursa.  It  is  continuous  with  the  pouch  which  the  synovial  mem- 
brane of  the  knee-joint  sends  upwards  above  the  patellar  surface 
of  the  femur. 

Action  of  the  Vasti  and  Crureus. — These  three  muscles  act  as 
powerful  extensors  of  the  knee-joint,  the  lowest  fibres  of  the  vastus 
internus  at  the  same  time  drawing  the  patella  inwards. 

Subcrureus. — ^This  muscle  is  in  reality  the  lowest  and  deepest 
portion  of  the  crureus.  Viewing  it  as  an  independent  muscle,  it 
arises  in  two  bundles  from  the  front  of  the  femur  about  4  inches 
above  the  patellar  surface,  and  it  is  inserted  into  the  suprapatellar 
bursa,  which  is  continuous  with  the  upward  prolongation  of  the 
synovial  membrane  of  the  knee-joint  above  the  patellar  surface  of 
the  femur. 

Nerve-supply. — The  articular  branch  to  the  knee-joint  which 
comes  from  the  innermost  muscular  branch  to  the  crureus. 

Action. — The  subcrureus  is  a  tensor  of  the  synovial  membrane  of 
the  knee-joint. 


THE  LOWER  LIMB  443 

Ligamentum  Patellae  (infrapatellar  tendon). — This  ligament  is 
realh"  a  continuation  of  the  common  tendon  of  the  quadriceps 
extensor  cruris,  the  patella  being  originally  a  sesamoid  cartilage 
developed  in  that  tendon.  It  is  a  very  strong,  flat,  broad  ligament, 
about  2  inches  in  length.  It  is  attached  superiorly  to  the  blunt 
apex  and  adjacent  margins  of  the  lower  part  of  the  patella,  and 
inferiorly  to  the  lower  rough  half  of  the  tubercle  of  the  tibia,  a 
bursa  intervening  between  the  tendon  and  the  upper  smooth  half  of 
that  tubercle. 

Anterior  Crural  Nerve. — This  is  the  largest  branch  of  the  lumbar 
plexus,  its  fibres  being  derived  from  the  dorsal  divisions  of  the 
second,  third,  and  fourth  lumbar  nerves.  In  the  abdomen  the 
nerve  lies  deeply  between  the  psoas  magnus  and  iliacus  muscles, 
and  in  this  position  it  passes  into  the  thigh  beneath  Poupart's 
ligament.  In  the  upper  part  of  Scarpa's  triangle  it  continues  to  lie 
deeply  between  these  two  muscles,  being  outside  the  crural  sheath 
and  about  \  inch  to  the  outer  side  of  the  common  femoral  artery. 
In  this  situation  the  nerve  becomes  broad  and  flat,  and,  at  a  point 
about  f  inch  below  Poupart's  ligament,  it  breaks  up  into  two 
divisions.  One  of  these  is  called  the  superficial  or  anterior  division, 
and  it  is  partly  muscular  and  partly  cutaneous  ;  the  other  is  called 
the  deep  or  posterior  division,  and  it  is  principally  muscular  and 
articular,  only  one  cutaneous  nerve,  namely,  the  long  saphenous, 
arising  from  it. 

Branches. — These  are  conveniently  divided  into  intra-abdominal 
and  extra-abdominal  or  femoral. 

The  intra-abdominal  branches  arise  from  the  trunk  of  the 
nerve,  and  are  as  follows  :  muscular,  three  or  four  in  number,  to 
the  iliacus  ;  and  an  arterial  branch  to  the  coats  of  the  femoral 
artery. 

The  extra-abdominal  or  femoral  branches  arise  from  the  two 
terminal  divisions  of  the  nerve  in  Scarpa's  triangle. 

The  branches  of  the  superficial  or  anterior  division  are  muscular 
to  the  sartorius  and  pectineus,  and  cutaneous,  namely,  middle 
cutaneous  and  internal  cutaneous,  to  the  integument  of  the  front 
and  inner  side  of  the  thigh,  and  of  the  inner  side  of  the  leg  in 
its  upper  half. 

The  branches  of  the  deep  or  posterior  division  are  muscular  to 
the  rectus  femoris,  vastus  externus,  vastus  internus,  crureus,  and 
subcrureus  ;  articular  to  the  hip-joint  and  knee-joint  (see  nerve- 
supply  of  quadricej)s  extensor  cruris)  ;  and  the  long  saphenous 
nerve,  already  described. 

Internal  Femoral  Muscles.  Gracilis  (adductor  gracilis)— Or/gm.— 
(I)  The  anterior  or  femoral  surface  of  the  body  of  the  os  pubis  in  its 
lower  half,  close  to  the  symj)hysis ;  and  (2)  the  front  of  the  descend- 
ing pubic  ramus  close  to  its  inner  border. 

Insertion. — The  upper  part  of  the  inner  surface  of  the  shaft 
of  the  tibia,  above  the  semitendinosus,  and  under  cover  of  the 
sartorius. 


444  A   MANUAL  OF  ANATOMY 

Nerve-supf>ly. — The  anterior  or  superficial  division  of  the  obturator 
nerve. 

Action. — The  muscle  is  an  adductor  of  the  thigh,  and  a  flexor  of 
the  knee-joint.  Having  flexed  the  knee-joint,  it  acts  as  an  internal 
rotator  of  the  leg. 

The  gracilis  is  flat  and  strap-like  in  the  upper  third  of  the  thigh. 
In  the  middle  third  it  becomes  thick  and  narrow,  and  it  gradually 
tapers  into  a  long,  narrow,  round  tendon  which  expands  towards 
its  insertion.  The  surfaces  are  directed  inwards  and  outwards,  the 
borders  looking  forwards  and  backwards.  In  the  lower  third  of 
the  thigh  the  tendon  has  the  sartorius  in  front  of  it,  and  the  semi- 
tendinosus  behind  it,  and  it  is  separated  from  the  internal  lateral 
ligament  of  the  knee-joint  by  a  bursa. 

Adductor  Longus — Origin. — The  upper  and  inner  part  of  the 
anterior  or  femoral  surface  of  the  body  of  the  os  pubis,  immediately 
below  and  external  to  the  pubic  angle. 

Insertion. — ^The  inner  lip  of  the  linea  aspera  of  the  femur. 

Nerve-supply. — The  anterior  or  superficial  division  of  the  obturator 
nerve. 

Action. — The  muscle  is  an  adductor  and  external  rotator  of  the 
thigh,  and  a  flexor  of  the  hip- joint. 

The  adductor  longus  is  a  flat,  triangular  muscle,  the  direction  of 
which  is  downwards,  outwards,  and  backwards.  It  lies  to  the  inner 
side  of  the  pectineus,  and  rests  upon  the  adductor  brevis,  the 
anterior  or  superficial  division  of  the  obturator  nerve,  and  the 
adductor  magnus.  The  superficial  femoral  artery  is  superficial  to 
it,  and  the  arteria  profunda  femoris  beneath  it. 

Adductor  Brevis — Origin. — (i)  The  anterior  or  femoral  surface  of 
the  body  of  the  os  pubis  for  rather  less  than  its  lower  half,  immedi- 
ately external  to  the  gracilis  ;  and  (2)  the  front  of  the  descending 
pubic  ramus,  where  it  is  likewise  external  to  the  gracilis. 

Insertion. — The  line  leading  from  the  back  of  the  small  trochanter 
to  the  inner  lip  of  the  linea  aspera. 

Nerve-supply. — The  anterior  or  superficial  division  of  the  obturator 
nerve  (occasionally  the  posterior  division). 

Action. — The  muscle  is  an  adductor  and  external  rotator  of  the 
thigh,  and  a  flexor  of  the  hip- joint. 

The  adductor  brevis  is  quadrilateral,  and  is  directed  downwards, 
outwards,  and  backwards.  It  lies  behind  the  pectineus  and  ad- 
ductor longus,  and  upon  the  adductor  magnus.  The  anterior  or 
superficial  division  of  the  obturator  nerve  is  in  front  of  it, 
and  the  posterior  or  deep  division  behind  it.  It  is  pierced  by 
the  first  two  perforating  branches  of  the  arteria  profunda 
femoris. 

Adductor  Magnus — Origin. — (i)  The  anterior  or  femoral  surface 
of  the  body  of  the  os  pubis  in  its  lower  fourth,  between  the  adductor 
brevis  internally  and  the  obturator  externus  externally  ;  (2)  the 
front  of  the  ischio-pubic  ramus  ;  and  (3)  the  inferior  portion  of  the 
postero-inferior  surface  of  the  tuber  ischii. 


THE  LOWER  LIMB 


445 


Insertion. — (i)  The  inner  side  of  the  gluteal  ridge  of  the  femur  : 
(2)  the  inner  lip  of  the  linea  aspera,  and  the  upper  part  of  the  internal 
supracondylar  ridge  for  fully  i  inch  ;  and  (3)  the  adductor  tubercle, 
by  means  of  a  narrow,  round  tendon  which  gives  a  fibrous  expansion 
to  the  internal  supracondylar  ridge  below  the  femoral  groove. 

Nerve-supply. — The  posterior  or  deep  division  of  the  obturator 
nerve.  The  postero-inferior  part  of  the  muscle,  representing  the 
fibres  which  arise  from  the  tuber  ischii,  is  supplied  by  the  branch  of 
the  great  sciatic  nerve  to  the  semimembranosus. 

Action. — The  muscle  is  a  powerful  adductor  of  the  thigh.  The 
part  inserted  into  the  shaft  of  the  femur  also  acts  as  an  external 
rotator  of  the  thigh,  and  the  part  extending  from  the  tuber  ischii  to 
the  adductor  tubercle  as  an  extensor  of  the  hip-joint. 

The  adductor  magnus  is  triangular  or  fan-shaped.     The  upper- 
most   fibres    are    hori- 
zontal ;    the    succeeding 
fibres  are  oblique;  and  f/   AWiiW^ 

those  which  arise  from  ''    /?\v,l 

the  tuber  ischii  are  al- 
most vertical.  The  part 
of  the  muscle  which  is 
inserted  into  the  inner  vastus 
side  of  the  gluteal  ridge  intemus 
usually  forms  a  distinct 
portion,  which  is  tri- 
angular in  shape,  and 
is  sometimes  called  the 
adductor  minimus.  The 
insertion  of  the  muscle 
into  the  shaft  of  the 
femur  is  interrupted  by 
four  tendinous  arches, 
which  give  passage  to 
the  perforating  branches 
of  the  arteria  profunda 
femoris.  Between  the 
tendon  which  descends 
to  the  adductor  tubercle 

and  the  part  of  the  muscle  which  is  inserted  into  the  up})er 
end  of  the  internal  supracondylar  ridge  there  is  an  aperture, 
called  the  femoral  opening,  for  the  passage  of  the  superficial 
femoral  vessels.  It  is  triangular,  with  the  apex  rounded  ofif, 
and  is  tendinous  in  front,  but  fleshy  behind.  It  is  of  larger  size 
than  is  necessary  for  the  ]:)assage  of  the  vessels,  being  so  adapted 
that  the  vessels  are  not  in  any  way  interfered  with  during  the 
action  of  the  muscle.  The  muscle  supports  the  adductor  brevis, 
adductor  longus,  and  ])osterior  or  deep  division  of  the  obturator 
nerve.  Its  j)osterior  surface  is  related  to  the  hamstring  muscles 
and  the  great  sciatic  nerve. 


Patella  . 


Tibia 


Fig.   225. 


Sartorius 

.  Gracilis 
.  Semimembranosus 

-Semitendinosus 


Gastrocnemius 


-The  Tendons  of  the  Inner  Side 
OF  THE  Knee. 


446 


A  MANUAL  OF  ANATOMY 


The  adductor  muscles  come  into  action  in  riding  upon  horseback,  enabling 
the  rider  to  grasp  the  saddle  with  his  thighs,  and  they  are  hence  called  '  the 
rider's  muscles.'  In  this  act  the  adductor  longus  is  specially  subjected  to 
strain,  and  its  narrow  round  tendon  of  origin  is  occasionally  ruptured.  At 
the  seat  of  rupture  ossification  sometimes  takes  place,  thus  giving  rise  to  the 
so-called  '  rider's  bone.' 

Obturator  Externus— Ong'm.— (i)  The  external  surface  of  the 
obturator  membrane  over  its  inner  half ;  (2)  the  adjacent  portion  of 


Obturator  Externus 
Quadratus  Femoris 


Adductor  Brevis 


Pectineus 


Adductor  Longus 


Adductor  Magnus 


Femoral  Opening ' 


Tendon  of  Adductor  Magnus 


Fig.  226. 


-The  Right  Internal  Femoral  Muscles  (Anterior  View). 
I,  2,  3,  4,  Openings  for  the  Perforating  Arteries. 


the  anterior  or  femoral  surface  of  the  body  of  the  os  pubis  ;  and 
(3)  the  front  of  the  ischio-pubic  ramus  close  to  the  obturator  fora- 
men. 

Insertion. — The  digital  or  trochanteric  fossa  of  the  femur. 

Nerve-sufply. — ^The  deep  or  posterior  division  of  the  obturator 
nerve  as  it  passes  through  the  upper  part  of  the  muscle. 

Action. — The  muscle  is  an  external  rotator  and  adductor  of  the 
thigh. 


THE  LOWER  LIMB  447 

The  obturator  externus  is  somewhat  triangular,  and  is  directed 
at  first  outwards,  and  then  backwards  and  upwards.  Its  round 
tendon  of  insertion  is  closely  applied  to  the  back  of  the  neck  of  the 
femur,  which  it  slightly  grooves  in  its  lower  or  extracapsular  part. 
The  superficial  or  anterior  division  of  the  obturator  nerve  passes 
over  the  upper  border  of  the  muscle,  and  the  deep  or  posterior 
division  pierces  the  upper  part  of  it.  The  muscle  is  in  close  contact 
with  the  lower  and  back  part  of  the  capsular  ligament  of  the  hip- 
joint,  a  bursa  being  usually  interposed. 

Obturator  Nerve. — This  nerve  is  a  branch  of  the  lumbar  plexus, 
and  generally  arises  by  three  roots  from  the  ventral  divisions  of  the 
second,  third,  and  fourth  lumbar  nerves,  but  the  root  from  the  second 
may  be  absent.  For  a  description  of  the  nerve  within  the  abdo- 
men and  pelvis,  see  these  sections.  It  escapes  from  the  pelvic 
cavity  by  passing  through  the  obturator  canal,  in  which  it  breaks 
up  into  two  divisions — superficial  or  anterior,  and  deep  or  posterior. 
The  superficial  or  anterior  division  passes  over  the  upper  border  of 
the  obturator  externus,  and  then  descends  in  front  of  the  adductor 
brevis,  but  behind  the  pectineus  and  adductor  longus.  This  division 
communicates  with  the  accessory  obturator  nerve  (when  present). 
The  deep  or  posterior  division  pierces  the  upper  part  of  the  obturator 
externus,  and  then  passes  behind  the  adductor  brevis  and  in  front 
of  the  adductor  magnus. 

Branches — Superficial  or  Anterior  Division. — The  branches  of 
this  division  are  as  follows  :  articular  to  the  hip- joint,  which 
arises  in  the  obturator  canal,  and  enters  the  joint  through  the 
cotyloid  foramen  ;  muscular  to  the  gracilis,  adductor  longus, 
adductor  brevis  as  a  rule,  and  occasionally  to  the  pectineus ; 
arterial  to  the  coats  of  the  femoral  artery ;  and  cutaneous. 
This  last  branch  commences  at  the  lower  border  of  the  adductor 
longus,  and,  after  a  short  course  downwards,  it  pierces  the  fascia 
lata  between  the  posterior  border  of  the  sartorius  and  the  anterior 
border  of  the  gracilis,  to  be  distributed  to  the  integument  of 
the  inner  side  of  the  thigh  for  a  variable  extent  about  the  centre. 
Before  this  branch  pierces  the  fascia  lata  it  gives  one  or  two  twigs 
which  communicate  with  branches  of  the  long  saphenous  and  the 
posterior  division  of  the  internal  cutaneous  beneath  the  sartorius, 
to  form  the  subsartorial  plexus. 

Deep  or  Posterior  Division. — This  division  furnishes  the  follow- 
ing branches  :  muscular  to  the  obturator  externus,  adductor 
magnus,  and  adductor  brevis  (provided  the  latter  is  not  supplied 
by  the  superficial  or  anterior  division)  ;  and  articular  to  the  knee- 
joint,  called  the  geniculate  branch.  This  latter  branch  descends  upon 
the  adductor  magnus,  which  it  subsequently  ])ierces  close  above 
the  femoral  opening,  and  so  reaches  the  popliteal  artery.  It  accom- 
j>anies  that  artery,  lying  at  first  on  its  inner  side  and  then  in  front  of 
it,  as  low  as  the  origin  of  the  central  or  azygos  branch.  Here  the 
nerve  leaves  the  main  artery,  and  passes  with  its  central  or  azygos 
branch  through  the   jjosterior   ligament  of   the  knee-joint  to   the 


448  A   MANUAL  OF  ANATOMY 

interior  of  the  articulation.  The  geniculate  nerve  is  frequently 
absent. 

Accessory  Obturator  Nerve.— This  nerve  is  present  in  about  30  per 
cent,  of  bodies.  It  is  comparatively  small  in  size,  and  arises  by 
two  roots  from  the  anterior  primary  divisions  of  the  third  and 
fourth  lumbar  nerves,  the  roots  being  interposed  between  those  of 
the  anterior  crural  and  obturator  nerves.  It  descends  along  the 
inner  border  of  the  psoas  magnus,  close  to  the  brim  of  the  pelvis, 
underneath  the  external  iliac  vessels.  It  then  passes  over  the 
superior  pubic  ramus,  where  it  passes  beneath  the  pectineus,  and 
so  emerges  on  to  the  thigh  beneath  Poupart's  ligament.  Under 
cover  of  the  pectineus  it  divides  into  the  following  three  branches  : 
(i)  articular  to  the  hip-joint ;  (2)  muscular  to  the  deep  surface  of 
the  pectineus  ;  and  (3)  a  reinforcing  branch  to  join  the  superficial 
or  anterior  division  of  the  main  obturator  nerve. 

Scarpa's  Triangle. — ^This  triangle  is  situated  on  the  front  of  the 
thigh  below  Poupart's  ligament.  The  base,  which  is  directed 
upwards,  is  formed  by  Poupart's  ligament.  The  outer  boundary 
is  formed  by  the  inner  border  of  the  sartorius  in  its  upper  fourth, 
and  the  inner  boundary  is  constructed  by  the  internal  border  of 
the  adductor  longus  in  its  upper  part.  The  apex  is  about  3-^  inches 
below  Poupart's  ligament,  and  is  formed  by  the  overlapping  which 
there  takes  place  between  the  superficially  placed  sartorius  and  the 
more  deeply  placed  adductor  longus.  The  roof  is  formed  by  the 
skin,  two  layers  of  the  superficial  fascia,  and  fascia  lata.  The 
following  structures  also  lie  in  the  roof  :  the  crural  branch  of 
the  genito- crural  nerve  ;  the  inguinal  and  superficial  femoral  or 
saphenous  glands  ;  the  cutaneous  branches  of  the  common  femoral 
artery  (except  the  inferior  external  pudic),  with  their  correspond- 
ing veins  ;  the  saphenous  opening  ;  and  the  terminal  part  of  the 
long  saphenous  vein,  with  the  anterior  and  posterior  saphenous 
veins  joining  it.  The  floor  contains  the  following  muscles,  in 
order  from  within  outwards  :  adductor  longus  ;  pectineus  ;  psoas 
magnus  ;  and  ihacus  (the  latter  two  being  here  united  to  form 
one  muscle,  called  the  iho-psoas).  Occasionally  a  small  part  of 
the  adductor  brevis  is  seen  between  the  adductor  longus  and 
pectineus,  and,  when  this  is  so,  the  superficial  or  anterior  division 
of  the  obturator  nerve  may  be  seen  in  part. 

Contents. — ^The  contents  are  as  follows  :  the  common  femoral 
artery  and  its  branches  ;  the  first  part  of  the  superficial  femoral 
artery  and  its  branches  ;  the  upper  part  of  the  femoral  vein  and 
its  tributaries  ;  and  the  anterior  crural  nerve,  with  its  divisions 
and  their  branches. 

Hunter's  Canal.* — ^This  is  a  somewhat  triangular,  musculo- 
aponeurotic  canal,  which  occupies  the  middle  two-fourths  of  the 
thigh  on  its  inner  aspect. 

*  The  canal  has  received  this  complimentary  name  because  John  Hunter  was 
the  first  surgeon  who  tied  the  superficial  femoral  artery  in  this  part  of  its  course 
for  popliteal  aneurism  in  the  year  1785. 


THE  LOWER  LIMB 


449 


Crural  Branch  of  Genito-crural  Nerve 

Superficial  Epigastric  Artery 


Obliquus  Externus  Abdominis  _  _  i_vvA^       V.  > 


E\t  Cutaneous  Ner\e 
Sup  Circumflex  line  Art 
Tensor  FaiCiae  temoris 

Iliacu^ 


Ant   Crural  Nei\e 


Femoral  \  em 

Mid   Cutani-ous 

Ner\e 

L.  Saphenous  Vein 

Sarlonus 


(  ommon  I  cmoral  Artery 

Hypogastric  Branch 

of  Ilio-hypogastric 

Nerve 


Sup.  Ext.  Pudic 
Artery 


^  Spermatic  Cord 


Iiif  ^  \t   Pudic  Artery 
\dductor  1  ongus 


_  (.  utancous  Branch  of 
(^  Obturatoi  Nerve 

^     -lutein  l1  (  utaneou^  Nerve 


Vastus  Inti  i 

Fig.  227.— The  Front  of  thk  Thigh  (Scarpa's  Triangle). 


29 


450  A  MANUAL  OF  ANATOMY 

Boundaries — External. — The  vastus  internus,  closely  covering  the 
inner  surface  of  the  femur  as  far  back  as  the  inner  lip  of  the  linea 
aspera.  Internal  and  Posterior. — ^The  adductor  longus  and  subse- 
quently the  adductor  magnus,  both  of  which  extend  back  to  the 
inner  lip  of  the  linea  aspera,  where  they  meet  the  vastus  internus  and 
so  form  the  apex  of  the  triangle.  Anterior  or  Superficial. — ^This 
boundary  is  commonly  called  the  roof  of  the  canal.  It  represents 
the  base  of  the  triangle,  and  is  formed  by  an  aponeurotic  expansion 
which  extends  from  the  adductor  longus  and  adductor  magnus  on 
the  inner  side  to  the  vastus  internus  on  the  outer  side.  Superficial 
to  this  expansion  in  its  whole  length  is  the  middle  portion  of  the 
sartorius,  and  the  subsartorial  plexus  of  nerves  lies  between  the 
two  in  the  middle  third  of  the  thigh.  The  aponeurosis  is  com- 
paratively weak  over  the  upper  half  of  the  canal,  but  over  the  lower 
half  it  is  strong,  and,  below,  it  is  continuous  with  the  anterior 
margin  of  the  femoral  opening  in  connection  with  the  adductor 
magnus. 

Contents. — ^These  are  as  follows :  the  superficial  femoral  artery  in 
the  second  part  of  its  course,  and  its  branches  ;  the  first  portion 
of  the  femoral  vein,  and  its  tributaries  ;  the  long  saphenous  nerve  ; 
and  the  nerve  to  the  vastus  internus  muscle  in  the  upper  half  of  the 
canal. 

Femoral  Artery. — This  vessel  extends  from  the  lower  border  of 
Poupart's  ligament  to  the  posterior  margin  of  the  femoral  opening, 
which  is  in  connection  with  the  adductor  magnus.  It  is  the  direct 
continuation  of  the  external  iliac  artery,  and  at  its  termination 
becomes  the  popliteal.  It  occupies  the  upper  three-fourths  of  the 
thigh,  and  its  direction  is  downwards  and  inwards.  The  course  of 
the  vessel  is  indicated  in  the  following  manner  :  the  thigh  being 
partially  flexed  upon  the  abdomen,  and  at  the  same  time  slightly 
abducted  and  rotated  outwards,  draw  a  line  from  a  point  midway 
between  the  anterior  superior  iliac  spine  and  the  symphysis  pubis 
to  the  adductor  tubercle  of  the  femur,  or,  if  this  tubercle  cannot  be 
felt,  to  the  internal  tuberosity  on  the  inner  surface  of  the  internal 
condyle.  This  line  over  its  upper  three-fourths  represents  the 
course  of  the  vessel. 

At  a  point  about  3-^  inches  below  Poupart's  ligament  the  sartorius 
takes  up  a  position  over  the  artery,  and  from  this  point  onwards 
that  muscle  continues  to  lie  over  the  vessel.  For  at  least  the  first 
i|-  inches  of  its  course  the  vessel  corresponds  in  size  with  the 
external  iliac  artery.  When,  however,  it  reaches  a  point  from  i-^ 
inches  to  2  inches  below  Poupart's  ligament  it  gives  off  a  large 
branch,  called  the  arteria  profunda  femoris,  after  which  it  under- 
goes a  sudden  diminution  m  size.  The  part  of  the  vessel  between 
Poupart's  ligament  and  the  origin  of  the  arteria  profunda  femoris 
is  known  as  the  common  femoral  ;  the  part  beyond  the  origin  of 
that  large  branch  is  called  the  superficial  femoral ;  and  the  arteria 
profunda  femoris  is  spoken  of  as  the  deep  femoral  ;  that  is  to  say, 
the  common  femoral  artery  is  regarded  as  dividing  into  superficial 


THE  LOWER  LIMB  451 

femoral  and  deep  femoral  at  a  point  from  i^  inches  to  2  inches  below 
Poupart's  ligament.  For  convenience  of  description,  the  femoral 
artery  (meaning  thereby  the  whole  of  the  leading  artery  of  the 
thigh)  is  divided  into  two  parts — first  and  second — the  first  part 
lying  in  Scarpa's  triangle,  and  the  second  part  occupying  Hunter's 
canal. 

First  Part. — The  first  part  of  the  femoral  artery  extends  from  the 
lower  border  of  Poupart's  ligament  to  the  apex  of  Scarpa's  triangle, 
within  which  triangle  it  lies. 

Relations — Superficial  or  Anterior. — The  skin  ;  superficial  fascia 
in  two  layers  ;  fascia  lata  ;  anterior  wall  of  the  crural  sheath  for 
the  first  i|  inches,  and  subsequently  the  anterior  wall  of  the  special 
sheath  ;  internal  cutaneous  nerve  crossing  the  vessel  from  without 
inwards,  either  as  one  nerve  or  in  its  two  divisions,  just  above  the 
apex  of  Scarpa's  triangle  and  outside  the  special  sheath  ;  two  or 
three  cutaneous  branches  of  the  internal  cutaneous  nerve  on  their 
way  to  the  inner  side  of  the  thigh  ;  superficial  circumflex  iliac  vein 
near  Poupart's  ligament ;  and  external  cutaneous  femoral  or 
anterior  saphenous  vein  just  above  the  apex  of  Scarpa's  triangle. 

Deep  or  Posterior. — The  posterior  wall  of  the  crural  sheath  for 
the  first  i^  inches,  and  subsequently  the  femoral  vein  ;  branch  of 
the  anterior  crural  nerve  passing  inwards  to  the  pectineus  muscle, 
and  lying  close  behind  the  crural  sheath  ;  psoas  magnus  in  the  upper 
part  and  pectineus  in  the  lower  part,  the  artery  being  separated 
from  the  latter  muscle  by  the  femoral  vein  and  profunda  femoris 
vessels,  the  femoral  vein  being  nearest  to  the  artery. 

External. — ^The  crural  branch  of  the  genito-crural  nerve  for  a 
short  distance  below  Poupart's  ligament,  where  the  nerve  is  within 
the  crural  sheath  ;  anterior  crural  nerve  for  about  |  inch  below 
Poupart's  ligament,  and  separated  from  the  artery  by  an  interval 
of  about  \  inch  ;  long  saphenous  nerve  and  nerve  to  the  vastus 
internus  muscle,  the  former  being  nearest  to  the  artery,  and  both 
being  outside  the  special  sheath  ;  and  the  arteria  profunda  femoris 
for  about  |  inch  at  its  commencement. 

Internal.— ¥ov  about  2  inches  below  Poupart's  ligament  the 
femoral  vein  lies  to  the  inner  side  of  the  artery,  with  the  intervention 
of  the  external  septum  of  the  crural  sheath.  Thereafter  the  vein 
gradually  leaves  the  inner  side  of  the  artery  to  take  up  its  position 
behind  it,  towards  the  apex  of  Scarpa's  triangle. 

The  femoral  artery  immediately  below  Poupart's  ligament  is 
anterior  to  the  inner  part  of  the  head  of  the  femur,  but  in  the 
rest  of  its  course  the  vessel  is  situated  on  the  inner  side  of  that 
bone. 

Second  Part. — The  second  part  of  the  artery  (superficial  femoral) 
extends  from  the  ajx'x  of  Scarpa's  triangle  to  tlie  posterior  margin 
of  the  femoral  ojjening  in  connection  with  the  adductor  magnus, 
where  it  becomes  the  jjopliteal.  In  this  part  of  its  course  the 
superficial  femoral  lies  in  Hunter's  canal,  and  passes  over  the 
adductor  longus,  whilst  the  deep  femoral  is  behind  that  muscle. 

29 — 2 


452  A   MANUAL  OF  ANATOMY 

Relations — Superficial  or  Anterior. — The  skin  ;  superficial  fascia  ; 
long  saphenous  vein  ;  fascia  lata  ;  sartorius  ;  subsartorial  plexus  of 
nerves  ;  the  aponeurotic  covering  of  Hunter's  canal ;  and  the  long 
saphenous  nerve  in  the  act  of  crossing  the  vessel  from  its  outer  to 
its  inner  side.  External. — The  vastus  internus,  covering  the 
inner  surface  of  the  femur  ;  and  the  long  saphenous  nerve  and  the 
nerve  to  the  vastus  internus,  both  in  the  upper  half  of  the  canal. 
Internal. — At  first  the  adductor  longus,  and  lower  down  the 
adductor  magnus,  both  of  which  muscles  also  lie  behind  the  artery. 
In  Hunter's  canal  the  femoral  vein  still  maintains  its  position  close 
behind  the  artery  until  the  lower  end  of  the  canal  is  reached,  when 
the  vein  inclines  a  little  to  the  outer  side  of  the  artery. 

The  superficial  femoral  artery  in  Scarpa's  triangle,  as  well  as  in 
Hunter's  canal,  is  surrounded  by  a  sheath,  which  also  contains  the 
femoral  vein. 

Branches  of  the  Femoral  Artery. — The  branches  are  as  follows  : 
superficial  epigastric ;  superficial  circumflex  iliac ;  superior  or 
superficial  external  pudic  ;  inferior  or  deep  external  pudic  ;  arteria 
profunda  femoris  or  deep  femoral  (all  from  the  common  femoral)  ; 
muscular  (from  the  superficial  femoral  in  Scarpa's  triangle  and  in 
tEunter's  canal)  ;  saphenous  (from  the  superficial  femoral  in 
Scarpa's  triangle)  ;  and  anastomotica  magna  (from  the  superficial 
femoral  in  Hunter's  canal). 

The  superficial  epigastric  artery  arises  from  the  common  femoral 
about  I  inch  below  Poupart's  ligament.  It  then  pierces  the  crural 
sheath  and  the  cribriform  fascia,  or  the  outer  border  of  the 
saphenous  opening,  after  which  it  turns  upwards  over  Poupart's 
ligament  a  little  to  the  inner  side  of  the  centre,  and  ramifies 
in  the  integument  of  the  anterior  abdorninal  wall  as  high  as  the 
umbilicus.  In  its  course  it  supplies  branches  to  the  inguinal  glands, 
and  anastomoses  with  branches  of  the  deep  epigastric  of  the  ex- 
ternal iliac. 

The  superficial  circumflex  iliac  artery  frequently  arises  in  common 
with  the  superficial  epigastric.  Having  pierced  the  crural  sheath 
and  the  outer  border  of  the  saphenous  opening,  it  passes  outwards 
below  the  outer  half  of  Poupart's  ligament  to  the  anterior  part 
of  the  iliac  crest,  where  it  ramifies  in  the  integument  of  that 
neighbourhood.  In  its  course  it  supplies  branches  to  the  iliacus, 
sartorius,  and  outer  inguinal  glands,  and  anastomoses  with  the 
deep  circumflex  iliac  of  the  external  iliac,  and  the  gluteal  of  the 
internal  iliac. 

The  superior  or  superficial  external  pudic  artery  arises  from 
the  common  femoral  about  |  inch  below  Poupart's  ligament. 
Having  pierced  the  crural  sheath  and  cribriform  fascia,  it  emerges 
through  the  saphenous  opening,  after  which  it  passes  inwards 
and  upwards  over  the  spermatic  cord,  or  round  ligament  of  the 
uterus,  according  to  the  sex,  to  be  distributed  to  the  integument 
of  the  suprapubic  region,  the  adjacent  portion  of  the  scrotum  in  the 
male,  and  the  labium  majus  in  the  female,  and  the  dorsum  of  the 


THE  LOWER  LIMB 


453 


Superficial  Epigastric  and 
Superficial  Circumflex  Iliac  Arteries 


Common  Femoral  Artery 
'    Femoral  Vein 


Sartonus 


Anterior  Crural  Nerve 
Iliacus 


Ext.  Circumflex  Arterv 


-Ji-Peclineus 


Adductor  Magnus 

Cutaneous  Branch  of 
Obturator  Nerve 


.Subsartorial  Plexus 

Long  Saphenous  Nerve 
Sartorius  (cut) 


Long  Saphenous  Vein 

(cut) 


Patellar  Branch  of  Long  Saphenous  Nerve 

Fig.  228.— The  Front  and  Innkr  Siue  of  T)iii  Thigh 
(The  Sartorius  has  been  in  great  part  removed). 


454  -A   MANUAL  OF  ANATOMY 

penis  by  a  branch  which  extends  as  far  as  the  prepuce  in  the  vicinity 
of  the  corona  glandis,  lying  in  its  course  external  to  the  dorsalis 
penis  artery.  The  vessel  in  its  course  gives  branches  to  the  inner 
inguinal  or  pubic  glands,  the  deep  femoral  glands,  and  the  cover- 
ings of  the  spermatic  cord  or  of  the  round  ligament  of  the  uterus. 
It  anastomoses  with  (i)  the  cremasteric  branch  of  the  deep  epigastric, 
in  crossing  the  spermatic  cord,  that  branch  being  represented  in  the 
female  by  the  artery  of  the  round  ligament  of  the  uterus  ;  (2)  its 
fellow  of  the  opposite  side  ;  (3)  the  inferior  or  deep  external  pudic  ; 
and  (4)  the  dorsalis  penis  artery,  which  is  a  branch  of  the  internal 
pudic  from  the  internal  iliac. 

The  inferior  or  deep  external  pudic  artery  arises  from  the 
common  femoral  a  little  lower  down  than  the  preceding.  Unlike 
the  superior  branch,  it  does  not  pass  through  the  saphenous 
opening,  but,  after  piercing  the  crural  sheath,  it  passes  inwards 
on  the  pectineus  and  adductor  longus,  under  cover  of  the  fascia 
lata.  Having  reached  the  inner  side  of  the  thigh,  it  pierces  the 
fascia  lata  to  be  distributed  to  the  side  of  the  scrotum  in  the 
male  and  the  labium  majus  in  the  female.  In  its  course  it  gives 
branches  to  the  muscles  upon  which  it  rests,  and  anastomoses  with 
(i)  the  superior  or  superficial '  external  pudic,  (2)  the  cremasteric, 
and  (3)  the  superficial  perineal,  vv^hich  is  a  branch  of  the  internal 
pudic. 

The  four  arteries  just  described  are  spoken  of  as  the  cutaneous 
arteries  of  the  groin. 

Arteria  Profunda  Femoris  or  Deep  Femoral  Artery. — ^This  im- 
portant vessel  is  one  of  the  terminal  branches  of  the  common 
femoral,  arising  from  the  outer  and  back  part  of  that  artery  at  a 
point  from  i^  inches  to  2  inches  below  Poupart's  ligament.  At  first 
it  lies  for  about  \  inch  on  the  outer  side  of  the  superficial  femoral, 
where  it  rests  upon  the  iliacus.  It  then  bends  sharply,  and  passes 
inwards  over  the  pectineus,  where  it  lies  immediately  behind 
the  superficial  femoral  vessels  and  its  own  vein,  the  latter  being 
nearest  to  it.  Thereafter  it  descends  behind  the  adductor  longus, 
resting,  in  succession,  upon  the  adductor  brevis  and  adductor  magnus, 
and,  having  become  comparatively  small,  it  terminates  in  the  fourth 
or  last  perforating  artery.  As  the  profunda  vessel  passes  behind 
the  adductor  longus,  it  is  separated  by  that  muscle  from  the  super- 
fi.cial  femoral  artery. 

Branches. — ^The  branches  are  as  follows  :  external  circumflex  ; 
internal  circumflex  ;  and  perforating,  which  are  four  in  number. 

The  external  circumflex  artery,  which  is  of  large  size,  arises  from 
the  arteria  profunda  femoris  close  to  its  origin.  Its  direction  is 
outwards  beneath  the  sartorius  and  rectus  femoris,  and  between 
the  nerves  arising  from  the  posterior  division  of  the  anterior  crural, 
supplying  in  this  part  of  its  course  branches  to  the  surround- 
ing muscles,  and  resting  upon  the  crureus.  It  terminates  by 
dividing  into  three  sets  of  branches — ascending,  transverse,  and 
descending. 


THE  LOWER   LIMB 


455 


Tensor  Fasciae  Femoris- 
Sartorius  (cut)--- 

Gluteus  Medius-' 
Rectus  Femoris  (cut)--- 

Ext.  Circumflex  Artery,, - 

Arteria  Profunda  Femori-  -" 

Vastus  Externu-  - 

Long  Descending  Branch  of-- 
Ext.  Circumflex  Artery- 
Adductor  Longus  (cut)- 

Vastus  lnternu>- 
Superficial  Femoral  Artery-     \] 


Deep  Branch  of 
Anastomotica  Magna  Artery  ^ 


Tendon  of  Rectus  Femori; 


.Psoas  Magnus 

Commencement  of  Common 
_,--''  Femoral  Artery 


_,Pectineus  (cut) 

'    Superf.  Div.  of  Obt.  Nerve 
Deep  Div.  of  Obt.  Ner\  e 
piercing  Obt.  Ext. 
-      \dductor  Longus 
Gracilis  (cut) 


Adductor  Brevis 


Adductor  Magnus 


\nastomotica  Magna  Artery 


Geniculate  Branch  of 

Obturator  Nerve 
Tendon  of  Adductor  Magnus 
'X/ygos  Artery 
Semimembranosus 
,Graci!is 
Semitendinosus 


Tendon  of  Sartorius 

Fig.  229. — The  Front  and  Inner  Side  of  the  Thigh 
(Deep  Dissection). 


4S6  A  MANUAL  OF  ANATOMY 

The  ascending  branch  passes  upwards  beneath  the  tensor  fasciae 
femoris  to  the  fore  part  of  the  gluteal  region.  Its  branches 
supply  the  tensor  fascise  femoris  and  the  anterior  portions  of 
the  gluteus  medius  and  gluteus  minimus.  It  also  supplies  an 
articular  branch  to  the  hip-joint,  which  reaches  the  articulation 
under  cover  of  the  rectus  femoris.  The  ascending  branch  anasto- 
moses with  the  gluteal  of  the  posterior  division  of  the  internal 
iliac,  and  the  deep  circumflex  iliac  of  the  external  iliac. 

The  transverse  branches  are  at  least  two  in  number.  They  enter 
the  vastus  externus,  in  which  they  wind  round  the  outer  part  of 
the  femur,  supplying  that  muscle  in  their  course.  One  of  them, 
piercing  the  femoral  insertion  of  the  gluteus  maximus,  reaches  the 
back  of  the  thigh,  where  it  anastomoses  with  the  first  perforating 
artery,  the  sciatic,  and  the  transverse  branch  of  the  internal  circum- 
flex, thus  forming  the  crucial  anastomosis. 

The  descending  branches  are  three  or  four  in  number.  They 
pass  downwards  with  the  nerve  to  the  vastus  externus,  lying 
along  the  anterior  border  of  that  muscle,  and  supplying  in  their 
course  the  rectus  femoris,  vastus  externus,  and  crureus.  One  of 
them  is  long,  and  descends  upon  the  vastus  externus  as  low  as  the 
knee-joint,  where,  piercing  that  muscle,  it  anastomoses  with  the 
superior  external  articular  of  the  popliteal,  the  fourth  or  lowest 
perforating  of  the  arteria  profunda  femoris,  the  deep  branch  of  the 
anastomotica  magna  of  the  superficial  femoral,  and  the  lowest 
muscular  branch  of  the  superficial  femoral.  The  other  descending 
branches  anastomose  in  the  crureus  with  the  lower  two  perforating 
arteries. 

The  internal  circumflex  artery  is  of  smaller  size  than  the 
external.  Arising  from  the  inner  and  back  part  of  the  arteria 
profunda  femoris,  opposite  the  origin  of  the  external  circumflex, 
it  passes  backwards  round  the  inner  side  of  the  femur  towards  the 
small  trochanter.  In  this  course  it  passes,  in  succession,  between 
the  pectineus  and  psoas  magnus,  and  between  the  adductor  brevis 
and  obturator  externus,  giving  off  branches  to  the  obturator 
externus  and  adductor  muscles.  On  reaching  the  interval  be- 
tween the  adductor  brevis  and  obturator  externus,  it  terminates 
in  two  branches  —  ascending  or  anterior,  and  transverse  or 
posterior. 

The  ascending  or  anterior  branch  passes  with  the  obturator 
externus  to  the  digital  fossa  of  the  femur,  where  it  anastomoses 
with  the  gluteal  and  sciatic  of  the  internal  iliac,  and  the  first 
perforating,  thus  forming  the  digital  anastomosis. 

The  transverse  or  posterior  branch  continues  the  course  of  the 
main  artery  backwards,  passing  between  the  upper  border  of  the 
adductor  magnus  and  lower  border  of  the  quadratus  femoris, 
in  which  situation  it  anastomoses  with  one  of  the  transverse 
branches  of  the  external  circumflex,  the  first  perforating,  and 
the  sciatic  of  the  internal  iliac,  thus  forming  the  crucial  anasto- 
mosis.     The  branches  which  the  internal  circumflex  gives  to  the 


THE  LOWER  LIMB  457 

obturator  externus  anastomose  in  that  muscle  with  the  obturator 
arterv.  which  is  a  branch  of  the  internal  iliac. 

The  perforating  arteries  are  four  in  number — first,  second,  third, 
and  fourth.  They  pass  backwards  round  the  inner  side  of  the 
femur,  and  under  the  tendinous  arches  of  the  adductor  magnus.  The 
first  and  second  arteries  pierce  the  adductor  brevis  and  adductor 
magnus,  whilst  the  third  and  fourth  pierce  the  adductor  magnus 
only.  On  reaching  the  back  of  the  thigh,  all  four  arteries  give 
off  the  following  branches  :  muscular,  to  the  hamstring  muscles  ; 
branches  to  the  great  sciatic  nerve ;  and  cutaneous,  to  the 
integument  of  the  outer  and  back  parts  of  the  thigh.  The  first 
perforating  also  gives  branches  to  the  lower  part  of  the  gluteus 
maximus,  and  the  second  (or  third)  furnishes  the  chief  nutrient  or 
medullary  artery  of  the  femur.  The  perforating  arteries,  now  much 
reduced  in  size,  wind  round  the  back  and  outer  side  of  the  femur. 
In  this  course  the  first  pierces  the  femoral  insertion  of  the  gluteus 
maximus,  and  the  second,  third,  and  fourth  pierce  the  femoral  head 
of  the  biceps  and  the  external  intermuscular  septum.  The  first  and 
second  terminate  in  the  vastus  externus,  and  the  third  and  fourth 
in  the  crureus,  all  four  anastomosing  with  branches  of  the  external 
circumflex,  the  fourth  also  taking  part  in  the  deep  geniculate  arterial 
rete.  At  the  back  of  the  thigh  the  perforating  arteries  anastomose 
freely  with  one  another.  The  first  perforating  also  anastomoses 
with  the  gluteal,  sciatic,  and  ascending  branch  of  the  internal 
circumflex  in  the  digital  fossa,  thus  forming  the  digital  anastomosis, 
and  with  the  sciatic  and  transverse  branches  of  the  internal  and 
external  circumflex  between  the  adductor  magnus  and  quadratus 
femoris  to  form  the  crucial  anastomosis.  The  lower  two  perforating 
arteries  anastomose  at  the  back  of  the  thigh  with  the  superior 
muscular  branches  of  the  popliteal.  The  branches  of  the  per- 
forating arteries  to  the  great  sciatic  nerve  anastomose  with  the 
comes  nervi  ischiadici  branch  of  the  sciatic. 

The  muscular  branches  of  the  superficial  femoral  artery  arise 
partly  in  Scarpa's  triangle  and  partly  in  Hunter's  canal.  The 
lowest  of  these  branches,  which  is  somewhat  large  and  very 
constant,  is  given  off  at  the  lower  end  of  Hunter's  canal.  It 
passes  outwards  behind  the  femur,  piercing  the  external  inter- 
muscular septum  and  the  femoral  head  of  the  biceps,  and  it  termi- 
nates in  the  crureus,  in  which  it  anastomoses  with  the  long 
descending  branch  of  the  external  circumflex,  the  fourth  perforating, 
and  the  su])erior  external  articular  of  the  popliteal. 

The  saphenous  branches  are  two  or  three  in  number,  and  arise 
from  the  superficial  femoral  in  Scarpa's  triangle.  They  supply 
the  superficial  femoral  or  saphenous  glands  and  the  structures 
around  the  terminal  i)art  of  the  long  saphenous  vein. 

The  arteria  anastomotica  magna  arises  from  the  superficial 
femoral  at  the  lower  end  of  Hunter's  canal,  and  at  once  divides 
into  a  sujjerficial  and  deej)  branch.  In  many  cases  these  branches 
arise  independently  from  the  main  vessel.     The  superficial  branch 


458  A   MANUAL  OF  ANATOMY 

pierces  the  aponeurotic  covering  of  Hunter's  canal,  and  descends 
in  company  with  the  long  saphenous  nerve  between  the  sartorius 
and  gracilis,  where  it  lies  beneath  the  fascia  lata.  It  subsequently 
pierces  that  fascia,  and  enters  the  leg  on  its  inner  aspect,  to  be 
distributed  to  the  integument  over  the  upper  third.  This  branch 
anastomoses  with  the  inferior  internal  articular  of  the  pop- 
liteal. The  deep  branch  at  once  enters  the  vastus  internus,  in 
which  it  descends  anterior  to  the  tendon  of  the  adductor  magnus. 
It  gives  branches  to  the  vastus  internus  and  crureus,  and  anasto- 
moses with  the  superior  internal  articular  of  the  popliteal.  It  also 
furnishes  a  cross  branch,  which  passes  outwards  in  front  of  the  femur 
above  the  patellar  surface  to  form  an  arch  with  a  branch  of  the 
superior  external  articular  of  the  popliteal.  Additional  anasto- 
moses are  formed  with  the  long  descending  branch  of  the  external 
circumflex,  and  the  lowest  perforating  branch  of  the  arteria  pro- 
funda femoris. 

Varieties  of  the  Femoral  Artery — I.  The  Trunk. — (i)  In  rare  cases  the 
femoral  artery  may  be  found  on  the  back  of  the  thigh  in  company  with  the 
great  sciatic  nerve.  In  such  cases  the  vessel  is  derived  from  the  internal  iliac, 
and  may  be  regarded  as  a  large  sciatic  artery.  Under  these  conditions  the 
external  iliac  artery  ends  as  the  arteria  profunda  femoris. 

(2)  Occasionally  the  superficial  femoral  artery  divides  just  below  the  origin 
of  the  arteria  profunda  femoris  into  two  branches  of  equal  size,  which  descend 
in  close  contact,  and  subsequently  unite  to  form  one  trunk  before  reaching 
the  femoral  opening  in  connection  with  the  adductor  magnus. 

II.  The  Branches — (i)  Arteria  Profunda  Femoris. — In  normal  cases  this 
artery  arises  from  the  common  femoral  from  i|^  to  2  inches  below  Poupart's 
ligament.  The  common  femoral  artery,  however,  may  divide  into  superficial 
femoral  and  deep  femoral  at  any  point  between  this  and  Poupart's  ligament. 
The  superficial  and  deep  femoral  arteries  may  even  spring  from  the  lower 
part  of  the  external  iUac  a  little  above  Poupart's  ligament,  in  which  case  two 
large  arteries  would  pass  out  beneath  that  ligament,  instead  of  one.  More 
rarely,  the  division  of  the  common  femoral  into  superficial  and  deep  femoral 
may  take  place  lower  down  than  the  normal  level,  even  as  low  as  4  inches  below 
Poupart's  ligament. 

(2)  External  Circumflex  Artery. — This  vessel  is  very  liable  to  variation. 
It  may  arise  from  the  common  femoral  instead  of  the  deep  femoral,  as  in  cases 
of  low  origin  of  the  latter  vessel,  or  it  may  arise  in  two  branches,  one  from 
the  deep  femoral  and  one  from  the  common  femoral,  or  both  from  the  deep 
femoral,  or  both  from  the  common  femoral. 

(3)  Internal  Circumflex  Artery. — This  vessel  is  not  so  hable  to  variation 
as  the  external  circumflex.  It  may  arise  along  with  the  external  circumflex  ; 
it  may  spring  from  the  common  femoral  ;  it  may  be  a  branch  of  the  deep 
epigastric  ;  or  it  may  be  derived  from  the  external  iliac. 

In  cases  of  low  origin  of  the  deep  femoral,  the  external  and  the  internal 
circumflex  arteries  usually  spring  from  the  common  femoral. 

(4)  Arteria  Anastomotica  Magna. — In  very  rare  cases  the  superficial  branch 
of  this  artery  assumes  considerable  length,  and,  under  the  name  of  the  internal 
saphenous  artery,  accompanies  the  internal  saphenous  vein  down  the  inner 
side  of  the  leg  as  far  as  the  internal  malleolus. 

Unusual  Branches. — The  deep  epigastric,  the  deep  circumflex  iliac,  or 
an  abnormal  obturator  artery,  may  arise  from  the  common  femoral  near 
Poupart's  ligament. 

Collateral  Circulation  after  Occlusion  of  the  Femoral  Artery. — i .  The  Common 
Femoral  Artery. — (a)  The  superficial  perineal  and  dorsalis  penis  arteries,  both 
from  the  internal  pudic  of  the  internal  iliac,  anastomose  with  the  superior  and 
inferior  external  pudics  of  the  common  femoral. 


THE  LOWER  LIMB  459 

(b)  The  cremasteric  from  the  deep  epigastric  of  the  external  iUac  anastomoses 
with  the  superior  external  pudic  of  the  common  femoral. 

(c)  The  obturator  of  the  internal  ihac  anastomoses  with  the  internal  circum- 
flex of  the  arteria  profunda  femoris. 

(d)  The  deep  circumflex  ihac  from  the  external  iliac  and  the  gluteal  from  the 
internal  ihac  anastomose  with  the  ascending  branch  of  the  external  circumflex 
from  the  arteria  profunda  femoris. 

(e)  The  sciatic  of  the  internal  iliac  anastomoses  with  the  transverse  branch 
of  the  internal  circumflex,  the  transverse  branch  of  the  external  circumflex, 
and  the  first  perforating  artery,  all  branches  of  the  arteria  profunda  femoris. 

(/)  The  sciatic  and  gluteal,  both  branches  of  the  internal  ihac,  anastomose  in 
the  digital  fossa  with  the  ascending  branch  of  the  internal  circumflex  of  the 
arteria  profunda  femoris. 

2.  The  Superficial  Femoral  Artery  below  the  Origin  of  the  Arteria  Profunda 
Femoris. — (a)  The  descending  branch  of  the  external  circumflex  of  the  arteria 
profunda  femoris  takes  part  in  the  deep  geniculate  arterial  rete. 

(b)  The  third  and  fourth  perforating  branches  of  the  arteria  profunda 
femoris  anastomose  at  the  back  of  the  thigh  with  the  superior  muscular 
branches  of  the  popliteal. 

(c)  The  fourth  perforating  artery  and  the  descending  branch  of  the  external 
circumflex,  both  from  the  arteria  profunda  femoris,  anastomose  with  the  lowest 
muscular  branch  of  the  superficial  femoral. 

A  continuous  anastomotic  chain  of  arteries  extends  from  the  gluteal  region 
down  the  back  of  the  thigh  to  the  region  of  the  knee,  and  it  is  formed  in  the 
following  manner  :  the  gluteal  anastomoses  with  the  sciatic,  the  sciatic  with 
the  external  and  internal  circumflex,  the  gluteal,  sciatic,  external  circumflex, 
and  internal  circumflex  with  the  perforating  branches  of  the  arteria  profunda 
femoris,  and  the  perforating  branches  of  the  arteria  profunda  femoris  with 
the  upper  muscular  and  articular  branches  of  the  popliteal.  This  chain  is  of 
special  importance  after  occlusion  of  the  common  femoral  artery,  and  the 
comes  nervi  ischiadici  branch  of  the  sciatic  is  particularly  liable  to  enlarge- 
ment. 

Femoral  Vein. — This  vessel  extends  from  the  posterior  margin  of 
the  femoral  opening,  which  is  in  connection  with  the  adductor 
magnus,  to  the  lower  border  of  Poupart's  ligament,  where  it 
becomes  the  external  iliac  vein.  In  the  lower  part  of  Hunter's 
canal  it  lies  close  behind  the  superficial  femoral  artery,  with  a 
slight  inclination  to  the  outer  side.  In  ascending,  however, 
it  soon  takes  up  a  position  behind  the  artery,  which  it  main- 
tains until  it  has  entered  Scarpa's  triangle.  The  vein  now  gradually 
inclines  to  the  inner  side  of  the  artery,  and  for  about  2  inches  below 
Poupart's  ligament  it  is  quite  to  its  inner  side,  but  on  the  same 
plane,  being  separated  from  the  artery  by  the  external  septum  of 
the  crural  sheath,  and  lying  here  between  the  pectineus  and  psoas 
magnus. 

"Tributaries. — ^These  are  as  follows :  the  venae  comites  of  the 
anastomotica  magna  artery  at  the  lower  end  of  Hunter's  canal; 
the  venae  comites  of  each  of  the  muscular  branches  of  the  super- 
ficial femoral  artery :  the  jirofunda  femoris  vein  at  a  point  about 
i|  inches  below  Poui)art's  ligament ;  and  the  long  saphenous 
vein  at  a  point  about  i\  inches  below  Poupart's  ligament,  and 
above  the  jjoint  where  the  profunda  vein  terminates.  The  long 
saphenous  vein  has  been  previously  reinforced  by  the  anterior 
saphenous  or  external  cutaneous  femoral,  the  posterior  sai)henous 
or  internal  cutaneous  femoral,  the  superficial  circumflex  iliac,  the 


46o 


A   MANUAL  OF  ANATOMY 


superficial  epigastric,  and  the  superior  and  inferior  external  pudic 
veins. 

The  profunda  femoris  vein  is  formed  by  the  ven^  comites 
which  accompany  each  of  the  branches  of  the  arteria  profunda 
femoris.     It  is  a  large  vessel,  and  is  provided  with  several  valves. 


Common  Iliac  Artery 

External  Iliac  Artery 

Internal  Iliac  Artery 


Femoral  Vein 

Poupart's  Ligament 

'    External  Abdominal 
Ring 


Crural  Branch  of 
Genito-crural  Nerve 

Psoas  Magnus 

Common  Origin  of  Superficial 
Epigastric  and  Superficial 
Circumflex  Iliac  Arteries 
Common  Femoral  Artery 

Internal  Saphenous  Vein.  WJ' 

Arteria  Profunda  Femoris 

External  Circumflex.- 
Artery 

W  ''//I 

II!  f^ 
III    '  ;_™._^ 


Obturator 
Membrane 


Fig.   230. — Deep  Dissection  of  Scarpa's  Triangle, 

The  femoral  vein  is  provided  with  five  pairs  of  valves.  Three  of 
these  are  situated  in  the  part  of  the  vessel  below  the  point  where 
it  receives  the  profunda  femoris  vein.  Of  the  other  two,  one  is 
placed  immediately  above  the  termination  of  the  profunda  femoris 
vein,  and  the  other  at  the  point  where  the  femoral  vein  ends  in  the 


THE  LOWER  LIMB  461 

external  iliac.     This  last  valve  is  known  as  the  ilio-femoral  valve 
of  Bennett. 

Varieties  of  the  Femoral  Vein. — i.  The  vein  is  sometimes  absent  from 
Hunter's  canal.  In  such  cases,  instead  of  passing  through  the  femoral 
opening  in  connection  with  the  adductor  magnus,  it  ascends  for  some  distance 
upon  the  posterior  surface  of  that  muscle,  which  it  subsequently  pierces,  and 
so  enters  Scarpa's  triangle. 

2.  The  vein  ma}'  be  double,  simulating  the  arrangement  known  as  venae 
comites,  in  which  case  the  femoral  artery  would  have  a  vein  on  either  side 
of  it,  with  communicating  branches  passing  between  the  two  at  frequent 
intervals  over  the  vessel. 

Obturator  Artery. — This  vessel  normally  arises  from  the  anterior 
division  of  the  internal  iliac,  and  for  the  most  part  is  placed 
on  the  outer  wall  of  the  pelvic  cavity.  The  artery,  having 
passed  through  the  obturator  canal,  divides  at  once  into  its  two 
terminal  branches,  internal  and  external.  These  descend  upon  the 
anterior  surface  of  the  obturator  membrane  under  cover  of  the 
obturator  externus,  the  internal  branch  coursing  along  the  inner 
margin,  and  the  external  along  the  outer  margin,  of  the  membrane. 
The  internal  branch  supplies  the  obturator  externus  and  adjacent 
adductor  muscles.  The  external  branch  divides  into  two  at  the  lower 
part  of  the  obturator  membrane.  One  of  these  divisions  passes 
inwards  and  anastomoses  with  the  internal  branch,  thus  completing 
an  arterial  loop  at  the  circumference  of  the  membrane.  The  other 
division  takes  an  outward  course  below  the  acetabulum  to  the 
region  of  the  tuber  ischii,  where  it  supplies  the  origins  of  the  ham- 
string muscles  and  anastomoses  with  the  sciatic  artery.  This  latter 
division  supplies  an  articular  branch  to  the  hip- joint,  which  passes 
beneath  the  transverse  ligament.  The  external  branch,  in  addi- 
tion to  the  foregoing  offsets,  supplies  the  obturator  externus,  in 
which  both  terminal  branches  anastomose  with  the  internal 
circumflex  of  the  arteria  profunda  femoris. 

The  obturator  vein  terminates  in  the  internal  iliac  vein. 


THE   HIP-JOINT. 

The  hip-joint  belongs  to  the  class  diarthrosis,  and  to  the  sub- 
division enarthrosis.  The  articular  surfaces  are  the  head  of  the 
femur  and  the  acetabulum  of  the  os  innominatum.  The  ligaments 
are  the  ca])sular  ligament,  with  its  accessory  parts,  the  ligamentum 
teres,  the  cotyloid  ligament,  and  the  transverse  ligament. 

The  capsular  ligament  is  of  great  strength,  and  completely 
surrounds  the  joint.  It  is  tight-fitting,  and  hardly  admits  of 
separation  taking  jjlace  between  the  articular  surfaces.  Its 
superior  attachments  are  as  follows  :  above  and  behind  it  is 
attached  to  the  os  innominatum  immediately  external  to  the  coty- 
loid ligament  and  about  three  lines  from  the  brim  of  the  acetabulum. 
In  front  it  is  attached  to  the  base  of   the  anterior  inferior  iliac 


462 


A   MANUAL  OF  ANATOMY 


spine  ;  the  outer  surface  of  the  cotyloid  hgament  ;  the  ilio- 
pectineal  eminence  ;  the  outer  extremity  of  the  obturator  crest 
of  the  superior  pubic  ramus  ;  and  the  adjacent  portion  of  the 
obturator  membrane.  Antero  -  inferiorly  (opposite  the  cotyloid 
notch)  it  is  attached  to  the  outer  surface  of  the  transverse  ligament. 
Inferiorly  it  is  attached  to  the  upper  part  of  the  groove  between 
the  acetabulum  and  the  tuber  ischii.  Its  inferior  attachments 
are  as  follows  :  superiorly  it  is  attached  to  the  anterior  part  of  the 
upper  border  of  the  great  trochanter  of  the  femur  and  the  superior 
cervical  tubercle.  Anteriorly  it  descends  as  low  as  the  anterior 
intertrochanteric  line,  into  which  it  is  firmly  implanted  as  low  as 
the  inferior  cervical  tubercle.  Inferiorly  and  internally  it  is 
attached  to  the  femur  about  |  inch  in  front  of  the  small  trochanter. 


Anterior  Inferior  Iliac  Spine 


Ilio-femoral  Band 
(Y  Ligament 
of  Bigelow; 


Anterior  ^        ,  ^, 

Intertrochanteric       VA    ' '^ 
Line  ^  , 


al  Band 


Obturator  Membrane 


Fig.  231. — The  Right  Hip-Joint  (Anterior  View). 


Posteriorly  it  is  attached  very  loosely  to  the  neck  of  the  femur  at 
the  junction  of  the  middle  and  lower  thirds. 

The  majority  of  the  fibres  of  the  ligament  are  disposed  longi- 
tudinally, but  some  are  circular.  The  circular  fibres  are  best 
marked  at  the  posterior  and  inferior  parts  of  the  capsule,  where 
they  form  a  band,  nearly  1  inch  in  depth,  called  the  zona  orbicularis. 
In  certain  situations  the  longitudinal  fibres  form  thickened  bands 
which  constitute  the  accessory  portions  of  the  capsule.  These 
accessory  bands,  usually  designated  as  special  ligaments,  are  as 
follows  :  ilio-femoral,  ilio-trochanteric,  ischio-capsular,  and  pubo- 
femoral. 

The  ilio-femoral  ligament  has  been  compared  to  an  inverted  Y, 
and  is  known  as  the  Y-shaped  ligament  of  Bigelow.  It  is  situated 
on  the  anterior  aspect  of  the  capsule,  and  is  attached  superiorly 


THE  LOWER  LIMB 


463 


to  the  inferior  aspect  of  the  anterior  inferior  ihac  spine  below 
the  origin  of  the  straight  head  of  the  rectus  femoris.  The  lateral 
fibres  as  they  descend  form  two  strong  bands,  outer  and  inner, 
which  diverge  very  slightly  from  each  other.  The  inner  band 
passes  almost  vertically  to  be  attached  to  the  lower  end  of 
the  anterior  intertrochanteric  line  of  the  femur  and  the  inferior 
cervical  tubercle.  The  outer  band,  shorter  than  the  inner,  passes 
obliquely  downwards  and  outwards  to  be  attached  to  the  upper 
end  of  the  anterior  intertrochanteric  line  and  the  superior  cervical 
tubercle.  The  central  fibres  are  attached  to  the  middle  portion  of 
the  anterior  intertrochanteric  line,  and  the  part  of  the  capsule 
covered  by  them  is  comparatively  weak. 

The  ilio-trochanteric  ligament  is  situated  immediately  external  to 
the  outer  part  of  the  ilio-femoral  ligament.    It  is  attached  superiorly 


Digital  Fossa 


-Great  Trochanter 


-  Zona  Orbicularis 


"~- Extracapsular  part  of 
Neck  of  Femur 


Tuber  Ischii 


Small  Trochanter 


Fig.   232. — The  Right  Hip-Joint  (Posterior  View). 

to  the  lower  and  anterior  ]:)art  of  the  dorsum  ilii  immediately  above 
the  acetabulum,  close  to  the  upper  attachment  of  the  ilio-femoral 
ligament,  and  inferiorly  to  the  great  trochanter  in  the  region  of 
the  su]:)erior  cervical  tubercle. 

The  ischio-capsular  ligament  is  a  thickened  band  which  extends 
from  the  upjjer  part  of  the  obturator  groove  (just  below  the 
acetabulum)  to  the  zona  orbicularis. 

The  pubo-femoral  ligament  is  the  weakest  of  the  three  accessory 
ligaments.  Its  fibres  are  attached  in  a  somewhat  scattered 
manner  to  the  ilio-pectineal  eminence,  the  outer  part  of  the 
obturator  crest,  and  the  adjacent  portion  of  the  obturator  membrane. 
From  these  points  the  fibres  converge  to  be  attached  to  the  anterior, 
inner,  and  lower  parts  of  the  capsular  ligament,  where  they  lie  close 
to  the  inner  band  of  the  ilio-femoral  ligament. 


A   MANUAL  OF  ANATOMY 


In  addition  to  the  accessory  ligaments,  the  capsule  receives  ex- 
pansions from  the  reflected  head  of  the  rectus  femoris  and  gluteus 
minimus.  When  the  hip-joint  is  opened  the  innermost  fibres  of 
the  capsular  ligament  are  seen  to  be  reflected  upwards  from  their 
femoral  attachments  upon  the  neck  of  the  femur  as  far  as  the 
margin  of  the  articular  cartilage  of  the  head.  The  longitudinal 
folds  thereby  produced  are  called  retinacida.  Three  of  these  are 
specially  well  marked,  two  being  situated  anteriorly,  and  corre- 
sponding in  position  with  the  outer  and  inner  bands  of  the  ilio- 
femoral ligament,  and  the  other  being  situated  at  the  upper  and 
back  part  of  the  neck. 

The  capsular  ligament  is  strongest  anteriorly  and  superiorly. 

The  thinnest  part  is  situated 
between  the  ilio-femoral  and 
pubo-femoral  ligaments.  In 
this  region  there  is  sonie- 
times  an  opening  in  the 
capsule  which  allows  the 
bursa  beneath  the  ilio-psoas 
to  communicate  with  the 
synovial  membrane  of  the 
joint.  The  capsule  is  also 
thin  where  it  is  attached  to 
the  posterior  surface  of  the 
neck  of  the  femur  and  to 
the  transverse  ligament.  It 
is  to  be  noted  that,  though 
the  anterior  surface  of  the 
neck  of  the  femur  is  entirely 
covered  by  the  capsular 
ligament,  and  is  therefore 
intracapsular,  the  posterior 
surface  of  the  neck  is  only 
intracapsular  in  its  upper 
two-thirds,  the  lower  third 
being  wholly  extracapsular. 
The  ligamentum  teres  is 
also  called  the  inter  articular  ligament.  Its  femoral  extremity, 
which  is  single  and  somewhat  flattened,  is  attached  to  the 
upper  part  of  the  rough  pit  on  the  head  of  the  femur  behind 
and  below  its  centre.  On  approaching  the  cotyloid  notch,  the 
ligament  becomes  expanded  and  divides  into  two  bands,  which 
are  attached  to  the  margins  of  the  notch  and  to  the  under  surface  of 
the  transverse  ligament.  The  direction  of  the  ligament  is  down- 
wards from  the  femur  to  the  cotyloid  notch,  and  it  rests  upon  the 
Haversian  gland  in  the  bottom  of  the  acetabulum.  It  is  invested 
by  the  synovial  membrane  of  the  hip- joint,  which  forms  a  tubular 
prolongation  around  it.  A  small  nutrient  artery  is  conducted  by 
the  ligament  to  the  head  of  the  femur. 


Fig.   233. — Interior  of  the  Left 
Hip-Joint. 

Head  of  Femur ;    2,   Ligamentum  Teres ; 
3,    Haversian    Gland;    4,    Cartilage    of 
5,  Cotyloid  Ligament. 


Acetabulum 


THE  LOWER  LIMB  465 

Two  views  may  be  stated  regarding  the  morphology  of  the  hgamentum 
teres. 

1.  It  may  be  regarded  as  a  part  of  the  capsule  of  the  hip-joint  which  has 
been  cut  off  by  the  outgrowth  of  the  articular  surface  of  the  head  of  the  femur 
(Keith). 

2.  It  may  be  regarded  as  the  separated  tendon  of  the  pectineus  muscle 
(Bland-Sutton). 

The  cotyloid  ligament  is  a  firm  annular  band  of  fibro-cartilage 
which  is  implanted  upon  the  brim  of  the  acetabulum,  thereby  deep- 
ening that  cavity  and  bridging  over  the  cotyloid  notch.  Its  fibres 
are  oblique  in  direction,  and  are  for  the  most  part  attached  to  the 
outer  and  inner  surfaces  of  the  brim,  but  opposite  the  cotyloid 
notch  they  are  attached  to  the  transverse  ligament.  The  outer 
surface  of  the  cotyloid  ligament  is  convex,  whilst  the  inner  surface 
is  concave  and  is  closely  applied  to  the  head  of  the  femur.  Both 
surfaces  are  covered  by  the  synovial  membrane.  The  ligament  is 
triangular,  the  base  being  implanted  on  the  brim  of  the  acetabulum, 
and  the  apex  representing  the  free  margin,  which  is  incurved  so  as 
to  grasp  the  head  of  the  femur. 

The  transverse  ligament  bridges  over  the  cotyloid  notch.  It  is 
somewhat  complex  in  structure,  being  composed  of  three  bundles 
of  fibres  intimately  blended  with  one  another.  The  superficial 
bundle  is  formed  by  that  part  of  the  cotyloid  ligament  which 
stretches  over  the  notch.  The  other  two  bundles  are  more 
deeply  placed,  and  are  arranged  as  two  decussating  bands  extending 
between  the  margins  of  the  notch,  and  blending  closely  with  the 
superficial  bundle.  The  transverse  ligament  does  not  completely 
fill  up  the  cotyloid  notch,  a  space  being  left  between  the  ligament 
and  the  bottom  of  the  notch  for  the  passage  of  articular  vessels  and 
nerves. 

The  synovial  membrane  covers  the  anterior  surface  of  the  neck 
of  the  femur  and  the  upper  two-thirds  of  the  posterior  surface, 
passing  over  the  retinacula  and  extending  as  high  as  the  margin 
of  the  cartilage  covering  the  head.  From  the  neck  it  is  reflected 
over  the  inner  surface  of  the  capsular  ligament,  which  it  com- 
pletely invests.  After  leaving  the  capsular  ligament  at  its 
acetabular  attachments  it  passes  over  the  cotyloid  ligament,  and 
covers  both  of  its  surfaces.  Thereafter  it  is  reflected  over  the 
Haversian  gland  in  the  bottom  of  the  acetabulum,  from  which  it  is 
prolonged  as  a  tubular  sheath  around  the  ligamentum  teres  as  far  as 
the  pit  on  the  head  of  the  femur.  In  those  cases  where  the  capsular 
ligament  presents  an  opening  between  the  ilio-femoral  and  pubo- 
femoral ligaments,  the  synovial  membrane  is  in  communication 
through  that  opening  with  the  bursa  beneath  the  ilio-psoas.  It  is 
to  be  noted  that  the  ligamentum  teres,  though  intracapsular,  is 
extrasynovial.  Further,  the  synovial  membrane  is  visible  from 
the  exterior  of  the  joint  at  the  lower  part  of  its  posterior  aspect, 
on  account  of  the  very  slight  attachment  of  the  caj^sular  ligament 
to  the  back  of  the  neck  of  tin;  femur. 

The  so-called  synovial  or  Haversian  gland  occupies  the  rough 

30 


466  A  MANUAL  OF  ANATOMY 

pit  in  the  bottom  of  the  acetabulum,  and  is  simply  a  collection 
of  adipose  tissue  covered  by  the  synovial  membrane.  The  liga- 
mentum  teres  rests  upon  it,  and  the  synovial  membrane  which 
covers  it  is  thicker  and  more  vascular  than  elsewhere.  It  serves 
as  a  cushion  for  the  head  of  the  femur. 

Muscular  Relations.  —  Commencing  at  the  inner  aspect  of  the 
capsular  ligament  and  passing  over  its  anterior,  outer,  and  posterior 
surfaces  to  its  lower  part,  the  muscles  in  contact  with  the  ligament 
are  as  follows  :  (i)  pectineus  on  the  inner  aspect  and  adjacent  part 
of  the  anterior  surface  ;  (2)  ilio-psoas  in  front  ;  (3)  the  two  heads 
of  the  rectus  femoris,  with  the  tendon  formed  by  their  union, 
and  the  gluteus  minimus  on  the  outer  and  upper  aspects  ;  (4)  pyri- 
formis,  gemellus  superior,  obturator  internus,  and  gemellus  inferior 
on  the  upper  and  posterior  aspects  ;  and  (5)  obturator  externus  on 
the  posterior  and  inferior  aspects.  Between  the  ilio-psoas  and  the 
ligament  there  is  a  bursa,  which  sometimes  communicates  with 
the  synovial  membrane  of  the  joint  through  an  opening  in  the 
capsule. 

Arterial  Supply. — The  hip- joint  receives  its  arterial  supply  from 
the  following  sources  : 

1.  The  transverse  branch  of  the  internal  circumflex. 

2.  The  ascending  branch  of  the  external  circumflex. 

3.  The  external  terminal  branch  of  the  obturator. 

4.  The  inferior  branch  of  the  deep  division  of  the  gluteal. 

5.  The  sciatic. 

Nerve-supply. — The  hip- joint  receives  its  nerves  from  the  following 
sources  : 

1.  The  nerve  to  the  rectus  femoris,  which  is  a  branch  of  the  pos- 
terior division  of  the  anterior  crural. 

2.  The  anterior  or  superficial  division  of  the  obturator  nerve,  or 
the  accessory  obturator  when  it  is  present. 

3.  The  nerve  to  the  quadratus  femoris,  or,  if  that  nerve  does  not 
supply  an  articular  branch,  the  great  sciatic. 

The  first  two  nerves  are  branches  of  the  lumbar  plexus,  and  the 
others  are  derived  from  the  sacral  plexus. 

Movements. — These  are  as  follows  :  flexion,  extension,  abduction,  adduc- 
tion, rotation,  and  circumduction. 

Flexion. — This  is  of  two  kinds — ventral  and  dorsal.  In  ventral  flexion 
the  thigh  is  drawn  upwards  towards  the  anterior  abdominal  wall.  In  dorsal 
flexion  the  thigh  is  carried  backwards  beyond  the  perpendicular.  The  extent 
of  ventral  fle^don  depends  upon  the  condition  of  the  knee-joint,  being  greater 
when  that  joint  is  flexed  and  more  hmited  when  it  is  kept  extended.  Assuming 
the  knee-joint  to  be  flexed,  ventral  flexion  is  limited  by  the  coming  into  contact 
of  the  fleshy  parts  of  the  front  of  the  thigh  and  anterior  abdominal  wall. 
When  the  knee-joint  is  kept  extended,  ventral  flexion  is  checked  earlier  by 
the  tension  of  the  hamstring  muscles.  Dorsal  flexion  is  in  most  persons  soon 
checked  by  the  tightening  of  the  front  part  of  the  capsular  hgament. 

Extension. — In  extending  the  hip-joint  from  the  position  of  ventral  flexion 
the  movement  is  hmited  by  the  tightening  of  the  front  part  of  the  capsular 
ligament.  When  a  person  stands  at  rest  the  hip-joint  is  in  a  state  of  exten- 
sion. The  vertical  line  passing  through  the  centre  of  gravity  then  falls  behind 
the  centre  of  rotation  at  the  hip-joint,  and  there  is  thus  a  tendency  on  the 


THE  LOWER  LIMB  467 

part  of  the  pelvis  to  fall  backwards.  This  tendency,  however,  is  counter- 
acted by  the  tightening  of  the  capsular  ligament  in  front,  and  so  the  erect 
attitude  is  maintained  without  any  muscular  effort. 

Abduction. — This  movement  is  controlled  by  the  tightening  of  the  pubo- 
femoral hgament  and  the  lower  part  of  the  capsule  ;  the  locking  which  takes 
place  between  the  upper  border  of  the  neck  of  the  femur  and  the  adjacent 
margin  of  the  acetabulum  ;  and  the  tension  of  the  adductor  muscles. 

Adduction. — This  movement  is  controlled  by  the  outer  band  of  the  ilio- 
femoral Ugament  and  upper  part  of  the  capsule,  and  the  locking  which  takes 
place  between  the  inner  part  of  the  neck  of  the  femur  and  the  anterior  margin 
of  the  acetabulum.  If  the  hip-joint  is  flexed  adduction  is  also  controlled  by 
the  tightening  of  the  ligamentum  teres. 

Rotation. — This  consists  in  movement  of  the  femur  round  its  longitudinal 
axis  without  much  change  of  position.  The  axis  of  rotation  is  represented 
by  a  line  passing  through  the  centre  of  the  head  of  the  femur  to  meet  the 
vertical  Une  of  the  centre  of  gravity  of  the  lower  limb  at  a  point  corresponding 
with  the  middle  of  the  intercondylar  notch  when  the  knee-joint  is  extended. 

Rotation  may  take  place  outwards  or  inwards.  External  rotation  is  con- 
trolled by  the  tightening  of  the  outer  band  of  the  ilio-femoral  ligament. 
Internal  rotation  is  checked  by  the  tightening  of  the  ischio-capsular  ligament ; 
by  the  zona  orbicularis  ;  and  by  the  muscles  in  contact  with  the  back  of  the 
joint.     The  range  of  rotation  is  about  60  degrees. 

Circumduction. — This  is  a  composite  movement,  consisting  of  flexion, 
abduction,  extension,  and  adduction,  following  each  other  in  rapid  succession, 
the  result  being  that  the  femur  describes  a  cone,  the  head  of  the  bone  forming 
the  apex  and  the  lower  extremity  describing  the  circumference  of  the  base. 

Ligamentum  Teres. — This  ligament  is  loose  in  the  state  of  extension  of 
the  hip-joint,  but  becomes  tightened  in  flexion  and  adduction. 

Muscles  concerned  in  the  Movements — Flexion. — Iho-psoas,  rectus  femoris, 
sartorius,  pectineus,  adductor  longus,  and  adductor  brevis,  the  ilio-psoas 
being  the  most  powerful  flexor.  Extension. — Gluteus  maximus,  biceps  femoris 
by  its  ischial  head,  semitendinosus,  semimembranosus,  and  adductor  magnus 
by  the  fibres  which  extend  from  the  tuber  ischii  to  the  adductor  tubercle. 
Abduction. — Gluteus  medius,  gluteus  minimus,  gluteus  maximus  by  its  upper 
fibres,  tensor  fasciae  femoris,  and  sartorius.  Adduction. — Adductores  gracilis, 
longus,  brevis,  et  magnus,  pectineus,  gluteus  maximus  by  its  lower  fibres,  and 
obturator  externus.  Internal  Rotation. — Gluteus  medius  by  its  anterior  fibres, 
gluteus  minimus,  tensor  fasciae  femoris,  and  adductor  magnus  by  the  fibres 
which  extend  from  the  tul^er  ischii  to  the  adductor  tubercle.  External  Rota- 
tion.— Gluteus  maximus  by  its  lower  fibres,  gluteus  medius  by  its  posterior 
fibres,  pyriformis,  obturator  internus  and  gemelli,  quadratus  femoris,  pectineus, 
adductores  longus,  brevis,  et  magnus  (the  latter  by  the  fibres  which  are 
inserted  into  the  shaft  of  the  femur),  obturator  externus,  and  sartorius. 


Relation  of  Muscles  on  the  Femoral  Aspect  of  the  Body  of  the  Os  Pubis. 

Commencing  at  the  symphysis  pubis,  and  jiassing  outwards  as  far  as  the 
inner  margin  of  the  obturator  foramen,  the  relation  of  muscles  is  as  follows  : 
(i)  gracilis,  (2)  adductor  brevis,  (3)  a  small  portion  of  the  adductor  magnus, 
and  (4)  obturator  externus. 

The  adductor  longus  does  not  take  part  in  this  relation,  its  origin  being 
at  the  upper  and  inner  part  of  the  anterior  or  femoral  surface  of  the  body 
of  the  OS  pubis,  from  an  impression  which  can  be  covered  with  the  point  of 
the  little  finger. 

RelatioB  of  Muscles  at  the  Back  of  the  Upper  End  of  the  Shaft  of  the  Femur. 

Commencing  at  the  small  trochanter,  and  passing  outwards  over  the  back 
of  the  femur  as  far  as  the  outer  margin  of  the  gluteal  ridge,  the  relation 
of   muscles  is  as  follows:    (i)  i!io-j)Soas,   (2)  jjeclineus,  (3)  adductor   brevis, 

30—2 


468  A   MANUAL  OF  ANATOMY 

(4)  lower  fibres  of  the  quadratus  femoris,  (5)  adductor  magnus,   (6)  gluteus 
maximus,  and  (7)  vastus  externus. 

Relation  of  Muscles  along  the  Linea  Aspera  of  the  Femur. — Commencing  at 
the  outer  lip  of  the  linea  aspera,  and  passing  inwards  as  far  as  the  inner  lip, 
the  relation  of  muscles  is  as  follows  :  (i)  vastus  externus  and  crureus  in  one 
line;  (2)  short  head  of  biceps  femoris;  (3)  adductor  magnus;  (4)  adductor 
longus  ;  and  (5)  vastus  internus. 


THE  LEG. 

Landmarks. — The  sharp  sinuous  anterior  border  of  the  tibia,  being 
entirely  subcutaneous,  can  readily  be  felt,  and  will  guide  the  finger 
to  the  tubercle,  which  is  situated  at  its  upper  end,  where  it  gives 
attachment  to  the  ligamentum  patellae.  The  lower  border  of  the 
tubercle  corresponds  with  the  division  of  the  popliteal  artery 
into  anterior  and  posterior  tibial  vessels.  The  head  of  the  fibula 
forms  a  prominent  landmark  on  the  outer  side  of  the  leg,  and 
is  situated  about  i  inch  below  the  level  of  the  upper  surface  of 
the  external  tuberosity  of  the  tibia.  The  shaft  of  the  jfibula  is 
for  the  most  part  obscured  by  muscles.  It  can  be  felt,  however, 
over  its  lower  fourth.  The  bone  occupies  a  more  posterior  plane 
than  the  tibia.  The  prominence  along  the  front  of  the  leg  in  its 
upper  two-thirds  is  mainly  due  to  the  fleshy  belly  of  the  tibialis 
anticus. 

The  internal  and  external  malleoli  form  bold  projections  at  the 
lower  end  of  the  leg,  the  internal  being  formed  by  the  tibia,  and  the 
external  by  the  fibula.  The  malleoli  are  upon  the  same  plane 
posteriorly,  but  the  internal  malleolus  projects  further  forwards  than, 
and  does  not  descend  so  low  as,  the  external  malleolus  ;  that  is  to 
say,  the  internal  malleolus  is  a  little  higher  up  and  further  forwards 
than  the  external,  but  the  two  project  equally  far  back.  This  has 
to  be  borne  in  mind  in  Syme's  amputation  at  the  ankle-joint.  It 
should  be  carefully  noted  that,  whilst  the  internal  malleolus  looks 
directly  inwards,  the  internal  tibial  tuberosity  has  a  slight  in- 
clination backwards  as  well  as  inwards.  The  tendons  of  the  tibialis 
posticus  and  flexor  longus  digitorum  may  be  felt  behind  the  internal 
malleolus,  the  former  being  the  larger  and  in  close  contact  with  the 
bone.  If  the  inner  border  of  the  foot  is  raised  so  as  to  invert  the 
sole,  the  tendon  of  the  tibialis  posticus  will  be  more  readily  felt. 
The  tendons  of  the  peroneus  longus  and  peroneus  brevis  are  situated 
behind  the  external  malleolus,  where  they  lie  one  upon  the  other, 
the  brevis  tendon  being  in  close  contact  with  the  bone.  Several 
tendons  can  readily  be  felt  in  front  of  the  ankle-joint.  From 
within  outwards  they  are  as  follows  :  tibialis  anticus  ;  extensor 
proprius  hallucis  ;  extensor  longus  digitorum ;  and  peroneus  tertius. 
All  these  tendons  are  best  felt  in  the  living  subject  when  the  foot 
is  flexed  upon  the  leg — that  is  to  say,  when  the  foot  is  raised. 

The  back  of  the  leg  is  characterized  by  the  prominence 
of  the  calf,  which  is  produced  by  the  gastrocnemius  and  soleus 
muscles.      This   prominence   gives   place   interiorly   to   the   tendo 


THE  LOWER  LIMB  469 

Achillis,  which  stands  out  boldly  beneath  the  integument,  and 
subsides  at  the  tuber  calcis.  Upon  either  side  of  the  projection 
formed  by  the  tendo  Achillis  there  is  an  elongated  furrow. 
The  furrow  on  the  outer  side  indicates  the  situation  of  the  short 
saphenous  vein  and  nerve  and  the  peroneal  artery,  whilst  that  on 
the  inner  side  corresponds  with  the  position  of  the  posterior  tibial 
vessels  and  nerve. 

The  course  of  the  anterior  tibial  artery  on  the  front  of  the  leg  is 
indicated  by  a  line  drawn  from  the  superior  tibio-iibular  articula- 
tion to  the  centre  of  the  front  of  the  ankle-joint,  midway  between 
the  two  malleoli.  This  practically  coincides  with  the  outer  border 
of  the  tibialis  anticus.  The  course  of  the  posterior  tibial  artery 
corresponds  with  a  line  drawn  from  the  centre  of  the  popliteal  space 
to  a  point  midway  between  the  tip  of  the  internal  malleolus  and 
the  inner  part  of  the  point  of  the  heel. 

It  is  to  be  noted  that  another  large  artery  is  situated  upon  the 
back  of  the  leg.  This  is  the  peroneal  branch  of  the  posterior  tibial, 
and  in  operations  it  will  be  caught  upon  the  back  of  the  fibula,  the 
posterior  tibial  being  between  the  tibia  and  fibula,  except  in  the 
lower  part  of  the  leg,  where  it  lies  on  the  back  of  the  tibia. 

The  anterior  and  posterior  tibial  arteries  can  readily  be  com- 
pressed with  one  hand  by  placing  the  thumb  in  front  of  the  ankle- 
joint  midway  between  the  two  malleoli,  and  the  middle  finger 
midway  between  the  tip  of  the  internal  malleolus  and  the  inner 
part  of  the  point  of  the  heel. 

The  long  saphenous  vein  may  be  visible  in  front  of  the  internal 
malleolus,  and  from  this  point  it  may  be  traceable  upwards  along 
the  internal  subcutaneous  surface  of  the  tibia. 

The  short  saphenous  vein  is  rarely  perceptible.  It  lies  behind 
the  external  malleolus,  then  in  the  hollow  upon  the  outer  side  of 
the  tendo  Achillis,  after  emerging  from  which  it  soon  gains  the 
middle  line,  where  it  lies  in  the  groove  between  the  two  heads  of 
the  gastrocnemius. 

Deep  Fascia. — The  deep  fascia  is  in  part  a  prolongation  of  the 
fascia  lata  of  the  thigh,  the  continuity  being  established  at  the  inner 
and  posterior  aspects  of  the  knee-joint.  Elsewhere  it  is  attached 
superiorly  to  the  head  of  the  fibula,  external  tuberosity  of  the  tibia, 
lower  part  of  the  patella,  ligamentum  patellae,  and  tubercle,  and 
front  of  the  internal  tuberosity,  of  the  tibia.  In  the  leg  it  is 
attached  to  the  crest  of  the  tibia,  from  which  it  is  prolonged  back- 
wards over  the  inner  surface  to  be  attached  to  the  internal  border. 
It  is  also  attached  to  the  antero-external  and  postero-external 
borders  of  the  fibula.  At  the  ankle  the  deep  fascia  is  attached  to 
the  internal  and  external  malleoli.  Over  the  inner  surface  of  the 
tibia  and  at  its  malleolar  attachments  it  becomes  closely  incorporated 
with  the  j)eriosteum.  The  chief  direction  of  the  fibres  of  the  fascia 
is  vertical.  There  are,  however,  superadded  transverse  fibres 
behind  the  knee-joint  and  in  the  vicinity  of  the  ankle-joint,  in 
which    latter    region    important    annular    ligaments    are    formed. 


470  A   MANUAL  OF  ANATOMY 

The  part  of  the  fascia  behind  the  knee-joint  presents  an  opening 
for  the  passage  of  the  short  saphenous  vein.  In  the  region  of  the 
gastrocnemius  and  over  the  inner  surface  of  the  tibia  the  deep  fascia 
is  very  thin.  Over  the  front  and  outer  parts  of  the  leg,  however, 
more  especially  in  the  upper  half,  it  attains  considerable  strength 
and  density,  and  there  it  gives  origin  by  its  deep  surface  to  the  super- 
ficial fibres  of  the  muscles  which  it  covers.  In  the  region  of  the 
knee-joint  it  receives  many  strong  accessions  of  fibres  from  the 
tendons  of  the  quadriceps  extensor  cruris,  biceps  femoris,  sartorius, 
gracilis,  and  semitendinosus. 

Four  expansions  are  given  off  from  its  deep  surface,  which  are 
called  intermuscular  septa — anterior,  antero  -  external,  postero- 
external, and  posterior  or  transverse.  The  anterior  intermuscular 
septum  is  limited  to  the  upper  third  of  the  leg,  where  it  extends 
between  the  tibialis  anticus  and  extensor  longus  digitorum,  to  both 
of  which  muscles  it  gives  partial  origin.  The  antero -external  inter- 
muscular septum  is  attached  to  the  antero-external  border  of  the 
fibula,  and  extends  between  the  extensor  longus  digitorum  and 
peroneus  tertius  on  the  anterior  surface,  and  the  peroneus  longus 
and  peroneus  brevis  on  the  external  surface.  The  postero-external 
intermuscular  septum  is  attached  to  the  postero-external  border 
of  the  fibula,  where  it  extends  between  the  peroneus  longus  and 
peroneus  brevis  on  the  external  surface,  and  the  soleus  and  flexor 
longus  hallucis  on  the  posterior  surface.  The  peroneus  longus 
and  peroneus  brevis  are  thus  completely  shut  off  from  the  adjacent 
muscles  by  the  two  external  intermuscular  septa.  These  septa, 
along  with  the  deep  fascia  at  the  surface  and  the  external  surface 
of  the  shaft  of  the  fibula,  form  a  long  fibro-osseous  canal  which 
contains  the  peroneus  longus  and  peroneus  brevis.  The  posterior 
or  transverse  intermuscular  septum  is  a  broad  expansion  which 
passes  transversely  between  the  postero-external  border  of  the 
fibula  and  the  internal  border  of  the  tibia.  It  lies  beneath  the 
soleus  and  upon  the  deep  muscles  of  the  back  of  the  leg,  as  well 
as  upon  the  posterior  tibial  vessels  and  nerve,  binding  down  the 
structures  which  it  covers. 

Annular  Ligaments. — These  are  situated  in  the  region  of  the 
ankle-joint,  and  are  thickened  portions  of  the  deep  fascia.  They 
serve  to  confine  and  maintain  in  position  the  strong  tendons  in  that 
vicinity,  and  are  three  in  number — external,  internal,  and  anterior. 

The  external  annular  ligament  extends  between  the  posterior 
border  of  the  external  malleolus  and  the  outer  border  of  the  tuber 
calcis  and  adjacent  portion  of  its  outer  surface.  Its  direction  is 
downwards  and  backwards  over  the  peroneal  groove  behind  the 
external  malleolus.  The  tendons  of  the  peroneus  longus  and 
peroneus  brevis  pass  beneath  it,  and  are  thereby  kept  in  position. 
The  tendon  of  the  peroneus  brevis  is  close  to  the  bone,  and  that  of 
the  peroneus  longus  is  directly  behind  the  brevis  tendon,  both 
being  invested  by  one  common  synovial  sheath.  The  external 
annular  ligament  at  its  anterior  border  is  continued  forwards  to 


THE  LOWER  LIMB 


471 


form  two  distinct  fibrous  sheaths  for  the  peroneal  tendons,  which 
are  here  lying  one  above  the  other  (the  peroneus  brevis  tendon 
being  the  upper  one)  as  they  traverse  the  outer  surface  of  the  os 
calcis.  Each  tendon  has  now  its  own  synovial  investment,  the 
common  synovial  sheath  beneath  the  external  annular  hgament 
having  sent  forward  two  prolongations. 

The  internal  annular  ligament  is  chiefly  formed  by  a  thicken- 
ing of  the  posterior  or  transverse  intermuscular  septum,  but  super- 
ficial to  it  there  is  also  the  proper  deep  fascia,  though  that  is  here 
very  thin.  This  annular  hgament  extends  between  the  posterior 
border  of  the  internal  malleolus  and  the  internal  border  of  the  tuber 
calcis,  and  is  directed  downwards  and  backwards.  Its  upper 
border  is  continuous  principally  with  the  posterior  intermuscular 

Tibialis  PosticuF.^. 
Flexor  Longus  Digitorum.^_ 

Posterior  Tibial  Artery  and  Venae  Comites,^  \'^ 

Posterior  Tibial  Nerve  _ 


Plantaris 


Abductor  Hallucis 


Internal  Annular  Ligament 


Fig.  234. 


-The  Structures  between  the  Internal  Malleolus 
AND  THE  Heel. 


septum.  Its  lower  border  gives  origin  on  its  deep  aspect  to  the 
inner  head  of  the  abductor  hallucis,  and  on  its  superficial  aspect 
it  is  in  part  continuous  with  the  lower  limb  of  the  Y  division 
of  the  anterior  annular  ligament.  The  internal  annular  ligament 
passes  over  the  grooves  on  the  back  of  the  lower  end  of 
the  tibia,  and  converts  these  into  canals  for  the  flexor  tendons  and 
posterior  tibial  vessels  and  nerve.  There  are  in  all  four  canals, 
three  of  them  being  fibro-osseous  and  one  fibrous.  The  relation  of 
structures  beneath  this  ligament,  from  the  internal  malleolus 
outwards  to  the  tuber  calcis,  is  as  follows  :  (i)  the  tendon  of  the 
tibialis  posticus,  lying  in  the  groove  behind  the  internal  malleolus 
close  to  the  bone,  and  occupying  one  of  the  fibro-osseous  canals  ;  (2) 
the  tendon  of  the  flexor  longus  digitorum,  lying  behind,  and 
slightly  external  to,  that  of  the  tibialis  posticus,  and  occupying  the 


472 


A  MANUAL  OF  ANATOMY 


fibrous  canal ;  (3)  the  internal  vena  comes,  posterior  tibial  artery, 
external  vena  comes,  and  posterior  tibial  nerve,  all  occupying  a 
second  fibro-osseous  canal ;  (in  cases  of  an  early  division  of  the 
posterior  tibial  nerve  into  external  and  internal  plantar  nerves 
these  two  nerves  are  found  in  this  canal,  the  internal  on  the  inner 
side  of  the  intei'nal  vena  comes,  and  the  external  on  the  outer  side 
of  the  external  vena  comes)  ;  (4)  the  tendon  of  the  flexor  longus 
hallucis,  occupying  the  third  fibro-osseous  canal,  and  lying  in  the 
groove  at  the  outer  part  of  the  posterior  border  of  the  lower  end  of 
the  tibia.  Each  of  the  three  tendons  mentioned  is  invested  by  a 
special  synovial  sheath.  The  internal  annular  ligament  is  pierced 
by  the  calcaneo-plantar  branch  of  the  posterior  tibial  nerve  and 
the  internal  calcaneal  branch  of  the  posterior  tibial  artery. 

The  anterior  annular  ligament  is  composed  of  two  divisions. 
One  division  is  situated  on  the  front  of  the  leg:  above  the  ankle- 


Tibialis  Amicus. Lsl 


Extensor  Proprius  Hallucis 


Tibialis  Posticus 

Flexor  Longus  Digitorum 


.Flexor  Longus  Hallucis 


Fig.  235. — The  Synovial  Sheaths  at  the  Ankle   (Internal  View) 
(after  L.  Testut's    '  Anatomie  Humaine'). 


joint,  and  is  called  the  superior  anterior  annular  ligament.  The 
other  division  lies  in  front  of  the  bend  of  the  ankle,  and  is 
called  the  inferior  anterior  annular  ligament,  anterior  annular 
ligament  proper,  or  lambdoid  ligament. 

The  superior  anterior  annular  ligament  is  a  broad  band  extending 
transversely  between  the  anterior  borders  of  the  tibia  and  fibula, 
and  measuring  about  2  inches  from  above  downwards.  Imme- 
diately beyond  it  the  deep  fascia  is  exceedingly  thin.  The 
structures  passing  beneath  it,  in  order  from  within  outwards,  are 
(i)  tibialis  anticus,  (2)  extensor  proprius  hallucis,  (3)  internal  vena 
comes,  (4)  anterior  tibial  artery,  (5)  external  vena  comes,  (6)  anterior 
tibial  nerve,  (7)  extensor  longus  digitorum,  and  (8)  peroneus 
tertius.  These  structures  occupy  one  common  compartment,  the 
tibialis  anticus  tendon  alone  being  surrounded  by  a  synovial  sheath. 


THE  LOWER  LIMB 


473 


Peroneus 
Longus 
et  Brevis 


Tibialis 
-Amicus 


which  is  continuous  with  that  investing  it  as  it  passes  through  the 
lambdoid  hgament. 

The  inferior  anterior  annular  or  lambdoid  ligament  is  a  more 
delined  structure  than  the  superior.  Being  placed  in  front  of 
the  ankle-joint,  it  serves  to  strap  down  the  extensor  tendons  as 
they  are  entering  upon  their  horizontal  course  on  the  dorsum  of 
the  foot.  It  may  be  likened 
either  to  the  capital  letter 
-<  placed  upon  its  side  as 
indicated,  or  to  the  Greek 
letter  -<  (lambda),  also 
laid  upon  its  side,  as 
shown.  From  the  former 
resemblance  it  may  be 
called  the  Y  annular  liga- 
ment. The  outer  part, 
which  is  a  single  narrow 
band,  is  attached  to  a 
depression  on  the  upper 
surface  of  the  os  calcis  at 
its  anterior  and  outer  part, 
immediately  in  front  of  the 
interosseous  groove.  This 
part  forms  a  loop  through 
which  the  tendons  of  the 
extensor  longus  digitorum 
and  peroneus  tertius  pass, 
invested  by  one  synovial 
sheath.  From  the  fact 
that  it  forms  a  loop  it 
has  been  called  by  Retzius 
the  fundiform  ligament.  It 
gives  partial  origin  to  the 
extensor  brevis  digitorum, 
and  at  its  inner  end  it  is 
continued  into  two  diverg- 
ing bands,  upper  and  lower. 
The  upper  band  is  attached 
to  the  internal  malleolus, 
and  the  tendon  of  the 
extensor  proprius  hallucis 
passes  underneath  it,  being 
surrounded  by  a  synovial  sheath.  The  tendon  of  the  tibialis 
anticus  passes  through  it,  the  main  portion  of  the  band  being 
underneath  that  tendon,  and  a  small  expansion  from  it  passing 
superficial  to  the  tendon.  The  tendon  of  the  tibialis  anticus 
has  its  own  synovial  sheath,  which  is  prolonged  upwards  from 
this  point  along  the  tendon,  to  be  continuous  with  the  synovial 
sheath    investing    it   as    it    passes    behinrl    the    superior    anterior 


Fig.  236. — The  Synovial  Sheaths  at  the 
Ankle  (Anterior  View)  (after  L. 
Testut's  'Anatomie  Humaine'). 


474  A  MANUAL  OF  ANATOMY 

annular  ligament.  The  lower  band  of  the  lambdoid  ligament 
is  a  comparatively  weak  structure  which  passes  to  the  inner 
border  of  the  foot,  where  it  joins  partly  the  plantar  fascia  and 
partly  the  lower  border  of  the  internal  annular  ligament.  The 
tendons  of  the  extensor  proprius  hallucis  and  tibialis  anticus 
both  pass  underneath  it.  There  are  thus  three  distinct  synovial 
sheaths  in  connection  with  the  lambdoid  ligament — one  for  the 
extensor  longus  digitorum  and  peroneus  tertius,  one  for  the  extensor 
proprius  hallucis.  and  one  for  the  tibialis  anticus,  the  latter  being 
continuous  with  that  which  invests  the  tendon  beneath  the  superior 
annular  ligament.  The  dorsalis  pedis  artery,  with  its  vena2  comites, 
and  the  dorsalis  pedis  nerve  pass  underneath  or  behind  both  bands 
of  the  fundiform  ligament. 

Internal  Aspect  of  the  Leg. 

The  internal  surface  of  the  tibia,  except  at  its  upper  end,  is  sub- 
cutaneous. The  deep  fascia  is  here  very  thin,  and  is  intimately 
incorporated  with  the  periosteum.  The  structures  met  with  on 
this  aspect  are  the  long  saphenous  vein  and  nerve,  the  posterior 
division  of  the  internal  cutaneous  nerve,  and  the  superficial 
branch  of  the  anastomotica  magna  artery.  The  long  saphenous 
vein  lies  about  a  finger's  breadth  from  the  internal  border  of  the 
tibia,  and  it  receives  many  tributaries  from  the  anterior  and  posterior 
aspects  of  the  leg.  The  long  saphenous  nerve  lies  immediately 
behind  it.  The  posterior  division  of  the  internal  cutaneous 
nerve  is  confined  to  the  upper  half  of  the  inner  aspect  of  the  leg, 
and  the  superficial  branch  of  the  anastomotica  magna  artery 
ramifies  in  the  upper  third.  At  the  upper  end  of  the  internal  surface 
of  the  tibia  the  tendons  of  insertion  of  the  sartorius,  gracilis,  and 
semitendinosus  are  met  with,  as  well  as  the  internal  lateral  ligament 
of  the  knee-joint.  Proceeding  in  a  direction  backwards  from  the 
tubercle  of  the  tibia  to  the  internal  border  of  the  bone,  the  relation 
of  these  structures  is  as  follows  :  (i)  tendon  of  the  sartorius ; 
(2)  tendons  of  the  gracilis  and  semitendinosus  in  the  same  vertical  line, 
the  gracilis  being  the  higher  of  the  two,  and  both  being  under  cover  of 
the  sartorius  ;  and  (3)  the  internal  lateral  ligament  of  the  knee-joint. 
The  tendons  of  the  gracilis  and  semitendinosus  cross  the  internal 
lateral  ligament  in  a  forward  direction,  and  are  separated  from 
it  and  the  subjacent  bone  by  a  bursa,  which  furnishes  an  expansion 
to  separate  them  from  the  more  superficially  placed  sartorius. 
The  portion  of  the  internal  lateral  ligament  met  with  in  this  region  is 
a  long,  flat,  expanded  band,  attached  to  the  internal  border,  and 
adjacent  portion  of  the  internal  surface,  of  the  tibia,  upon  which 
it  descends  for  fully  3  inches.  The  inferior  internal  articular 
artery  passes  transversely  forwards  underneath  it,  below  the  internal 
tuberosity  of  the  tibia  ;  and  beneath  the  posterior  border  of  the 
ligament  the  chief  tendon  of  the  semimembranosus  passes  to  be 
inserted  into  the  horizontal  groove  on  the  posterior  surface  of  the 
internal  tuberosity. 


THE  LOWER  LIMB 


475 


Anterior  Aspect  of  the  Leg  and  Dorsum  of  the  Foot. 

Musculo-eutaneous  Nerve  (Superficial  Peroneal). — This  nerve  is 
one  of  the  terminal  branches  of  the  external  popliteal,  arising  from 
that  nerve  on  the  outer  side  of  the  neck  of  the  fibula,  where  it  lies 
between  the  bone  and  the  peroneus  longus.  It  then  descends  in  the 
antero-external  intermuscular  septum,  lying  between  the  extensor 
longus  digitorum  in  front,  and  the  peroneus  longus  and  peroneus 
brevis  behind.  When  it  reaches  the  junction  of  the  upper  two- 
thirds  and  lower  third  of  the  leg,  it  becomes  cutaneous  by  piercing 
the  deep  fascia,  and  almost  immediately  afterwards  it  divides  into 
its  two  terminal  branches,  internal  and 
external. 

Branches.  —  The  branches  of  the 
nerve  are  as  follows  :  muscular  to  the 
peroneus  longus  and  peroneus  brevis  ; 
and  cutaneous  to  the  integument  of  the 
front  of  the  leg  in  its  lower  third, 
which  arises  as  soon  as  the  nerve 
pierces  the  deep  fascia. 

The  internal  terminal  branch 
descends  to  the  dorsum  of  the  foot, 
lying  superficial  to  both  divisions 
of  the  anterior  annular  ligament.  It 
then  divides  into  two  branches,  inner 
and  outer.  The  inner  branch  supplies 
twigs  to  the  integument  of  the  internal 
malleolus  and  inner  side  of  the  foot, 
which  communicate  with  the  terminal 
part  of  the  long  saphenous  nerve,  and 
it  then  becomes  the  dorsal  digital 
nerve  of  the  inner  side  of  the  great 
toe.  It  gives  a  communicating  branch 
to  the  dorsalis  pedis  nerve  as  that 
lies  upon  the  first  dorsal  interosseous 
muscle.  The  outer  branch  passes  to  the  cleft  between  the  second 
and  third  toes,  where  it  divides  into  two  dorsal  collateral  digital 
nerves  for  the  supply  of  the  contiguous  sides  of  these  toes. 

The  external  terminal  branch,  like  the  internal,  descends  to 
the  dorsum  of  the  foot,  and  also  lies  superficial  to  both  divisions 
of  the  anterior  annular  ligament.  On  the  dorsum  of  the  foot  it 
divides  into  two  branches,  inner  and  outer.  The  inner  branch 
passes  to  the  cleft  between  the  third  and  fourth  toes,  and  the 
outer  to  the  cleft  between  the  fourth  and  fifth  toes.  At  these 
clefts  the  inner  and  outer  branches  divide  each  into  two  dorsal 
collateral  digital  nerves  for  the  supply  of  the  contiguous  sides  of 
the  third  and  fourth,  and  fourth  and  fifth  toes.  The  outer 
branch   in    its   course   sui)])lies   twigs    to    the    integument    of    the 


Fig.    237. — Diagram    of    the 

Nerves  of  the  Foot 

(Dorsal  Aspect). 


4/6  A  MANUAL  OF  ANATOMY 

external  malleolus  and  outer  border  of  the  foot  which  communicate 
with  the  terminal  part  of  the  short  saphenous  nerve. 

Summary  of  the  Distribution  of  the  Musculo-eutaneous  Nerve. — The  nerve 
is  distributed  to  the  peroueus  longus,  pexoneus  "breAT-S,  integument  over  the 
front  of  the  leg  in  its  lower  third,  integument  of  the  malleolar  regions  and 
outer  and  inner  borders  of  the  foot,  and  the  integument  of  (i)  the  inner  side 
of  the  great  toe,  and  (;:)  the  contigTious  sides  of  the  second  and  third,  tinrd — ^' 
and  fourth,  and  fourth  and  fifth  toes,  all  on  their  dorsal  aspects.  The  dorsal 
digital  nerve  of  the  outer  side  of  the  fifth  toe  is  the  terminal  part  of  the  short 
saphenous  nerve. 

The  dorsal  collateral  digital  nerves  for  the  supply  of  the  contiguous  sides 
of  the  great  toe  and  second  toe  are  derived  from  the  dorsahs  pedis  nerve, 
which  is  the  continuation  of  the  anterior  tibial  ner\"e. 

Muscles.  Tibialis  Antieus — Origin. — (i)  The  external  tuberosity  of 
the  tibia  at  its  lower  part  :  (2)  the  upper  two-thirds  of  the  external 
surface  of  the  shaft  of  the  tibia  and  adjacent  portion  of  the  anterior 
surface  of  the  interosseous  membrane  :  and  (3)  the  deep  fascia,  and 
the  anterior  intermuscular  septum  which  lies  between  it  and  the 
extensor  longus  digitormu  in  the  upper  third  of  the  leg. 

Insertion. — ^The  tendon,  having  traversed  the  groove  on  the  inner 
surface  of  the  internal  cmreiform  bone,  divides  into  two  slips.  The 
posterior  shp  is  inserted  into  an  oval  impression  at  the  lower  part 
of  the  inner  surface  of  the  internal  cuneifonii  bone,  and  the 
anterior  shp  is  inserted  into  the  inner  surface  of  the  tuberosity  on 
the  plantar  aspect  of  the  base  of  the  first  metatarsal  bone. 

Nerve-supply. — The  anterior  tibial  nerve. 

Action. — (i)  To  flex  the  foot  upon  the  leg,  and  (2)  to  raise  the 
inner  border  of  the  foot,  thereby  inverting  the  sole. 

Extensor  Proprius  or  Longus  Hallucis— Or/gn?. — ^The  middle  two- 
fourths  of  the  anterior  surface  of  the  shaft  of  the  fibula,  and  the 
adjacent  portion  of  the  anterior  sm'face  of  the  interosseous  mem- 
brane. 

Insertion. — The  dorsal  surface  of  the  base  of  the  distal  phalanx 
of  the  gi-eat  toe. 

Nerve-supply. — The  anterior  tibial  nerve. 

Action. — (ij  To  extend  the  distal  phalanx  of  the  gi'eat  toe,  and 
(2)  to  flex  the  foot  upon  the  leg. 

The  extensor  proprius  hallucis  is  a  very  narrow  muscle  which  lies 
deeply  between  the  tibialis  antieus  and  extensor  longus  digitorum, 
both  of  which  conceal  it  until  its  tendon  appears  on  the  front  of  the 
lower  part  of  the  tibia. 

Extensor  Longus  Digitorum. — Origin. — (i)  The  external  tuber- 
osity of  the  tibia  :  (2)  the  head  and  upper  three-fourths  of  the 
anterior  surface  of  the  shaft  of  the  fibula  :  (3)  the  anterior  surface 
of  the  interosseous  membrane  in  its  upper  fourth  :  (4)  the  inter- 
muscular septa  between  it  and  adjacent  muscles  :  and  (5)  the  deep 
fascia. 

I nserti 071. —The  second  and  distal  phalanges  of  the  four  outer  toes. 
The  four  tendons  pass  to  the  dorsal  aspects  of  the  metatarso- 
phalangeal joints  of  the  four  outer  toes.     At  this  point  the}/  broaden 


THE  LOWER  LIMB  477 

out  into  expansions  which  receive  the  tendons  of  the  lumbricales 
and  interosseous  muscles.  In  the  case  of  the  tendons  destined  for 
the  second,  third,  and  fourth  toes,  their  expansions  are  also  joined 
by  the  outer  three  tendons  of  the  extensor  brevis  digitorum.  Each 
tendinous  expansion  passes  fonvards  over  the  dorsiun  of  the  first 
phalanx,  and  at  its  distal  end  divides  into  three  bands.  The 
middle  band  is  inserted  into  the  dorsal  aspect  of  the  base  of  the 
second  phalanx.  The  two  lateral  bands,  having  united,  are  inserted 
into  the  dorsal  aspect  of  the  base  of  the  distal  phalanx. 

Nerve-supply. — The  anterior  tibial  nerve. 

Actioyi. — (i)  To  extend  the  second  and  distal  phalanges  of  the 
four  outer  toes,  and  (2)  to  flex  the  foot  upon  the  leg. 

Peroneus  TqtXius— Origin. — (i)  The  anterior  surface  of  the  shaft 
of  the  fibula  m  its  lower  fourth,  except  for  an  inch  or  more  below, 
and  (2)  the  adjacent  portion  of  the  anterior  surface  of  the  inter- 
osseous membrane,  and  the  antero-extemal  intermuscular  septum 
between  the  muscle  and  the  peroneus  brevis. 

Insertion. — The  dorsal  surface  of  the  base  of  the  fifth  metatarsal 
bone. 

Nerve-supply. — The  anterior  tibial  nerve. 

Action. — (i)  To  flex  the  foot  upon  the  leg,  and  (2)  to  raise  the 
outer  border  of  the  foot  slightly. 

The  peroneus  tertius  is  to  be  regarded  as  a  detached  portion  of 
the  extensor  longus  digitorum. 

Anterior  Tibial  Artery. — This  vessel  is  one  of  the  terminal  branches 
of  the  popliteal  artery.  It  commences  at  the  lower  border  of  the 
popliteus  muscle  on  a  level  with  the  lower  border  of  the  tubercle 
of  the  tibia  (fully  i|  inches  below  the  level  of  the  upper  surface 
of  the  head  of  that  bone),  and  it  terminates  on  the  anterior  liga- 
ment of  the  ankle-joint  midway  between  the  two  malleoli  by 
becoming  the  dorsalis  pedis  artery.  Being  placed  at  its  commence- 
ment on  the  back  of  the  leg.  the  vessel  passes  at  first  forwards 
between  the  two  heads  of  the  tibialis  posticus,  and  over  the  upper 
border  of  the  interosseous  membrane,  where  it  lies  below  the  superior 
tibio-fibular  articulation.  (The  artery  sometimes  passes  through 
an  aperture  in  the  upper  part  of  the  interosseous  membrane,  called 
the  superior  hiatus.)  Having  reached  the  front  of  the  leg,  the 
vessel  changes  its  course  somewhat  abruptly,  and  then  descends 
in  close  contact  with  the  anterior  surface  of  the  interosseous  mem- 
brane, until  it  reaches  the  junction  of  the  upj>er  two-thirds  and 
lower  third  of  the  leg.  Beyond  this  point  it  gradually  inclines 
towards  the  anterior  asj^ect  of  the  tibia,  and  in  the  lower  fourth  it 
lies  upon  that  surface,  and  finally  upon  the  anterior  ligament  of 
the  ankle-joint.  The  course  of  the  vessel  on  the  anterior  aspect  of 
the  leg  corresponds  with  a  line  drawn  from  the  su^xfrior  tibio- 
fibular articulation  to  the  centre  of  the  front  of  the  ankle-joint 
midway  between  the  two  malleoli. 

Relations — On  the  Back  of  the  Leg. — The  artery  lies  here  between 
the  two  heads  of  the  tibialis  ix)sticus,  having  the  lower  border  of  the 


478 


A  MANUAL  OF  ANATOMY 


popliteus  muscle  above  it,  and  being  under  cover  of  the  gastro- 
cnemius. 

On  the  Front  of  the  Leg — Superficial. — In  the  upper  three-fourths 
the  artery  is  deeply  placed,  and  is  covered  by  the  integument, 
and  the  meeting  between  the  tibialis  anticus  on  the  inner  side  and 

the    extensor    longus 

Recurrent  Articular  Nerve 

Ext.  Popliteal  Nerve 


-Musculo-cutaneous  N. 
-Anterior  Tibial  Nerve 


•Anterior  Tibial  Artery 
and  Nerve 


Interosseous. 
Membrane 


digitorum  and  exten- 
sor proprius  hallucis 
on  the  outer  side.  In 
the  lower  fourth  the 
vessel  is  compara- 
tively superficial,  the 
muscles  having  now 
ended  in  their  ten- 
dons, and  it  is  covered 
by  the  integument, 
upper  division  of  the 
anterior  annular  liga- 
ment, and  extensor 
proprius  hallucis,  the 
tendon  of  the  latter 
muscle  crossing  it 
from  without  inwards 
about  3|  inches  above 
the  ankle-joint.  Deep. 
— Anterior  surface  of 
the  interosseous  mem- 
brane (to  which  it  is 
bound  by  fibrous 
tissue),  anterior  sur- 
face of  the  tibia  in 
lower  fourth,  and  the 
anterior  ligament  of 
the  ankle-joint.  Ex- 
ternal.— E  x  t  e  n  s  o  r 
longus  digitorum  in 
the  upper  fourth  of 
the  leg,  extensor  pro- 
prius hallucis  in  the 
middle  two  -  fourths, 
and  extensor  longus 
digitorum  again  in 
the  lower  fourth.  In- 
ternal.— ^Tibialis  anticus  in  the  upper  three-fourths,  and  extensor 
proprius  hallucis  in  the  lower  fourth. 

The  artery  is  accompanied  by  two  venae  comites,  which  closely 
embrace  its  sides  and  communicate  with  each  other  at  frequent 
intervals  by  transverse  branches,  crossing  superficial  to  the  vessel. 
These   vense   comites,   having  passed   backwards   over   the   upper 


-Extensor  Proprius 
Hallucis 


.Extensor  Longus 
Digitorum 


-Musculo-cutaneous  N. 
(Cutaneous  Portion) 

-Peroneus  Brevis 


Peroneus  Longus 


Fig.  238.- 


-The  Front  of  the  Left  Leg 
(Deep  Dissection). 


THE  LOWER  LIMB  479 

border  of  the  interosseous  membrane  (or  through  a  superior  hiatus 
in  it),  join  to  form  one  trunk,  which  unites  with  the  trunk  formed 
by  the  junction  of  the  venae  comites  of  the  posterior  tibial  artery 
to  form  the  pophteal  vein. 

The  anterior  tibial  artery  in  the  upper  fourth  of  the  leg  is 
separated  from  the  anterior  tibial  nerve  by  the  fibula  and  the 
extensor  longus  digitorum,  the  artery  having  passed  forwards 
between  the  tibia  and  fibula,  and  the  nerve  having  wound  obliquely 
round  the  outer  side  of  the  bone.  At  the  junction  of  the  upper 
fourth  and  lower  three-fourths  of  the  leg  the  nerve,  having  pierced 
the  antero-external  intermuscular  septum  and  extensor  longus 
digitorum,  comes  into  contact  with  the  artery,  along  the  outer 
side  of  which  it  descends  for  a  short  distance.  It  then  lies 
on  the  artery  for  a  little,  and  finally  it  again  takes  up  a 
position  upon  the  outer  side  of  the  vessel  in  the  lower  fourth  of 
the  leg. 

Branches. — The  branches  from  above  downwards  are  as  follows : 
posterior  tibial  recurrent  ;  superior  fibular ;  anterior  tibial  re- 
current ;  muscular  ;  internal  malleolar  ;  and  external  malleolar. 

The  posterior  tibial  recurrent  artery  is  an  inconstant  branch. 
When  present  it  arises  from  the  anterior  tibial  artery  whilst  on 
the  back  of  the  leg.  Its  course  is  upwards  beneath  the  popliteus 
muscle,  and  it  is  distributed  to  that  muscle,  the  posterior  liga- 
ment of  the  knee-joint,  and  the  superior  tibio-fibular  articulation. 
It  anastomoses  with  the  external  and  internal  inferior  articular 
arteries  on  the  back  of  the  leg. 

The  superior  fibular  artery  also  arises  from  the  anterior  tibial 
whilst  on  the  back  of  the  leg.  Its  course  is  outwards  behind 
the  neck  of  the  fibula,  where  it  pierces  the  soleus,  and  it  is 
distributed  to  that  muscle,  the  peroneus  longus,  and  the  adjacent 
integument. 

The  anterior  tibial  recurrent  artery  arises  from  the  anterior 
tibial  whenever  it  reaches  the  front  of  the  leg.  Entering  the 
upper  part  of  the  tibialis  anticus,  to  which,  as  well  as  to  the 
superior  tibio-fibular  joint,  it  gives  branches,  it  ascends  to  the 
external  tuberosity  of  the  tibia,  in  company  with  the  recurrent 
articular  branch  of  the  external  popliteal  nerve.  Its  terminal 
branches  anastomose  with  the  external  and  internal  inferior  arti- 
cular arteries. 

The  muscular  branches  are  very  numerous,  and  are  distributed 
chiefly  to  the  muscles  on  the  anterior  aspect  of  the  leg.  Some 
offsets,  however,  reach  the  integument,  and  others,  piercing  the 
interosseous  membrane,  terminate  in  the  tibialis  posticus,  in  which 
they  anastomose  with  branches  of  the  posterior  tibial  artery. 

The  internal  malleolar  artery  is  a  small  branch  which  arises 
from  the  inner  side  of  the  anterior  tibial  near  the  lower  end  of  the 
tibia.  Its  course  is  inwards  beneath  the  tendon  of  the  tibialis 
anticus,  and  it  is  distributed  over  the  internal  malleolus,  where  it 
anastomoses  with  (i)  the  internal  malleolar  branches  of  the  pos- 


48o  A  MANUAL  OF  ANATOMY 

terior  tibial,  (2)  the  superior  internal  tarsal  branch  of  the  dorsalis 
pedis,  and  (3)  branches  of  the  internal  plantar,  thus  forming  the 
internal  malleolar  anastomosis. 

The  external  malleolar  artery  arises  from  the  outer  side  of  the 
anterior  tibial  at  a  slightly  lower  level  than  the  internal  malleolar. 
Its  course  is  outwards  beneath  the  tendons  of  the  extensor  longus 
digitorum  and  peroneus  tertius,  and  it  is  distributed  over  the 
external  malleolus,  where  it  anastomoses  with  (i)  the  anterior 
peroneal,  (2)  the  posterior  peroneal,  and  (3)  the  external  tarsal 
branch  of  the  dorsahs  pedis,  thus  forming  the  external  malleolar 
anastomosis. 

The  veins  which  accompany  the  branches  of  the  anterior  tibial 
artery  are,  in  each  case,  arranged  as  venae  comites,  and  they  termi- 
nate as  tributaries  of  the  anterior  tibial  venae  comites. 

Varieties — i .  Origin. — The  vessel  may  arise  from  the  popliteal  at  the  upper 
border  of  the  popliteus  muscle.  In  these  cases  it  may  descend  on  the 
posterior  surface  of  that  muscle  (this  being  the  more  frequent  position),  or  it 
may  pass  deeply  in  front  of  it. 

2.  Course. — The  vessel  in  the  lower  fourth  of  the  leg  may  be  found  upon 
the  fibula  instead  of  the  tibia,  in  which  cases  it  makes  a  sudden  bend  at 
the  ankle-joint  to  become  the  dorsalis  pedis  artery.  In  very  rare  cases  the 
vessel  may  become  superficial  at  the  centre  of  the  leg  instead  of  in  the  lower 
fourth. 

'  3.  Size. — The  vessel  is  occasionally  very  small,  and,  if  the  diminution  in 
size  is  very  pronounced,  it  may  fail  to  furnish  the  dorsalis  pedis  artery,  in 
which  cases  that  vessel  is  supplied  bj^  the  anterior  peroneal. 

Anastomoses  round  the  Knee-Joint- — ^The  arteries  which  take 
part  in  these  anastomoses  are  as  follows  :  (i)  the  two  superior,  and 
the  two  inferior,  external  and  internal  articular  branches  of  the 
popliteal  ;  (2)  the  long  descending  branch  of  the  external  circum- 
flex of  the  profunda  femoris  ;  (3)  the  anastomotica  magna  of  the 
superficial  femoral ;  (4)  the  fourth  perforating  of  the  profunda 
femoris  ;  and  (5)  the  posterior  tibial  recurrent  (inconstant),  and 
the  anterior  tibial  recurrent,  both  of  which  are  branches  of  the 
anterior  tibial  artery.  For  the  special  anastomoses  of  the  foregoing 
arteries  see  the  descriptions  of  the  individual  vessels,  and  Fig.  251. 

The  anastomoses  are  divided  into  s^iperficial  and  deep,  the  former 
being  placed  superficial  to  the  patella,  and  the  latter  being  in  contact 
with  the  lower  end  of  the  femur  and  the  head  of  the  tibia. 

Three  transverse  arches  are  to  be  noted  anteriorly  as  follows  : 
one  lies  in  the  substance  of  the  crureus,  just  above  the  patellar 
surface  of  the  femur,  and  is  formed  by  branches  of  the  superior 
external  articular  of  the  polpiteal,  and  the  deep  branch  of  the 
anastomotica  magna  of  the  superficial  femoral.  A  second  arch 
lies  in  front  of  the  head  of  the  tibia,  near  the  superior  surface, 
and  is  formed  by  branches  of  the  inferior  external  articular, 
and  the  superior  internal  articular.  A  third  arch  lies  in  front 
of  the  tibia  just  above  the  tubercle,  and  is  formed  by  branches 
of  the  anterior  tibial  recurrent,  and  the  inferior  internal  articular 
artery. 


THE  LOWER  LIMB  481 

The  terminal  part  of  the  anterior  peroneal  artery,  having  reached 
the  front  of  the  leg  by  passing  through  the  inferior  hiatus  in  the 
interosseonQ  membrane,  descends  in  front  of  the  inferior  tibio- 
fibular articulation  under  cover  of  the  peroneus  tertius,  to  both  of 
which  it  furnishes  branches.  It  finally  takes  part  in  the  external 
malleolar  anastomosis,  along  with  (i)  the  external  malleolar  of  the 
anterior  tibial,  (2)  the  external  tarsal  of  the  dorsalis  pedis,  and 
(3)  the  posterior  peroneal. 

Anterior  Tibial  Nerve  (Deep  Peroneal). — This  nerve  is  one  of  the 
terminal  branches  of  the  external  popliteal.  It  commences  upon 
the  outer  side  of  the  neck  of  the  fibula,  where  it  lies  between  the 
bone  and  the  peroneus  longus,  and  it  terminates  at  the  anterior 
ligament  of  the  ankle-joint,  where  it  becomes  the  dorsalis  pedis 
nerve.  At  first  it  is  directed  downwards,  forwards,  and  inwards 
through  the  antero-external  intermuscular  septum  and  extensor 
longus  digitorum,  and  it  comes  into  contact  with  the  anterior 
tibial  artery  at  the  junction  of  the  upper  fourth  and  lower  three- 
fourths  of  the  leg.  It  then  descends  in  close  contact  with  that 
artery  as  far  as  its  termination,  lying  at  first  external  to  the  vessel, 
then  in  front  of  it,  and  finally  again  on  its  outer  side.  The  general 
relations  of  the  nerve  closely  correspond  with  those  of  the  artery 
on  the  front  of  the  leg. 

Branches. — ^These  are  muscular  and  articular.  The  muscular 
branches  supply  the  tibialis  anticus,  extensor  longus  digitorum, 
extensor  proprius  hallucis,  and  peroneus  tertius.  The  articular 
branches  arise  from  the  lower  part  of  the  nerve,  and  are  distributed 
to  the  ankle-joint  and  inferior  tibio-fibular  articulation. 

Anterior  Tibial  Gland. — This  lymphatic  gland  is  situated  in  front 
of  the  interosseous  membrane  at  its  upper  part  in  close  proximity 
to  the  anterior  tibial  artery.  Its  afferent  vessels  take  up  lymph 
from  the  dorsum  of  the  foot  and  anterior  aspect  of  the  leg  in  its 
more  deeply-placed  parts.  The  efferent  vessels,  which  are  usually 
two  in  number,  pass  backwards  either  above  the  interosseous 
membrane  or  through  a  superior  hiatus  in  it,  lying  along  the  anterior 
tibial  artery,  and  they  become  afferent  vessels  to  the  popliteal 
glands. 

Dorsum  of  the  Foot.  Deep  Fascia. — This  is  a  delicate  membrane 
which  is  prolonged  forwards  from  the  lambdoid  ligament  over  the 
long  extensor  tendons.  Two  other  thin  layers  of  deeji  fascia 
are  met  with,  one  covering  the  extensor  brevis  digitorum,  and 
the  other  covering  the  dorsal  interosseous  muscles  and  the  dorsal 
surfaces  of  the  metatarsal  bones. 

Extensor  Brevis  Digitorum — Origin.  —  (i)  The  anterior  part 
of  the  ui)per  surface,  and  adjacent  part  of  the  external  surface, 
of  the  OS  calcis  ;  and  (2)  the  outer  single  portion  of  the  lower 
division  of  the  anterior  annular  ligament — that  is  to  say,  the  fundi- 
form  ligament  of  Retzius. 

Insertion. — Into  the  four  inner  toes,  namely,  the  great  toe, 
second,  third,  and  fourth,  by  means  of  four  tendons  in  the  following 

31 


482  A  MANUAL  OF  ANATOMY 

manner  :  the  innermost  tendon  has  a  special  insertion  into  the 
dorsal  surface  of  the  first  phalanx  of  the  great  toe  near  its  base. 
The  other  three  tendons  join  the  outer  borders  of  the  long  extensor 
tendons  which  go  to  the  second,  third,  and  fourth  toes,  the  union 
taking  place  at  the  metatarso-phalangeal  joints. 

Nerve- supply. — The  external  branch  of  the  dorsalis  pedis 
nerve. 

Action. — (i)  Innermost  tendon. — This  tendon  extends  the  great 
toe  at  the  metatarso-phalangeal  joint,  and  it  also  acts  as  an  adductor 
of  that  toe.  (2)  Second,  third,  and  fourth  tendons. — These  extend 
the  corresponding  toes  in  conjunction  with  the  long  extensor 
tendons.  In  doing  so  they  tend,  by  the  obliquity  of  their  direction, 
to  draw  the  toes  outwards,  and  in  this  way  they  counteract  the 
opposite  tendency  of  the  long  extensor  tendons,  which  of  themselves 
would  incline  the  toes  inwards. 

The  muscle  lies  obliquely  upon  the  dorsum  of  the  foot,  and  is 
directed  forwards  and  inwards.  The  innermost  fleshy  bundle  is 
always  the  largest,  and  separates  from  the  parent  muscle  sooner 
than  the  others.  It  has  accordingly  been  regarded  as  a  separate 
muscle,  and  as  such  is  called  the  extensor  brevis  hallucis. 

Dorsalis  Pedis  Artery. — ^This  vessel  is  the  continuation  of  the 
anterior  tibial  artery.  It  commences  at  the  anterior  ligament  of 
the  ankle-joint,  midway  between  the  two  malleoli,  and  terminates 
at  the  proximal  end  of  the  first  interosseous  space,  where  it  divides 
into  two  branches,  plantar  or  perforating,  and  arteria  dorsalis 
hallucis  or  first  dorsal  interosseous  artery.  The  course  of  the  vessel 
is  along  the  inner  part  of  the  dorsum  of  the  foot,  and  is  indicated 
by  a  line  drawn  from  the  centre  of  the  front  of  the  ankle-joint, 
midway  between  the  two  malleoli,  to  the  proximal  end  of  the  first 
interosseous  space. 

Relations — Superficial. — The  skin,  superficial  fascia,  lower  division 
of  anterior  annular  ligament,  deep  fascia,  and  innermost  tendon 
of  the  extensor  brevis  digitorum,  which  crosses  it  from  without 
inwards  near  its  termination.  Deep. — Upper  border  of  the  head  of 
the  astragalus,  navicular,  middle  cuneiform,  base  of  second  meta- 
tarsal, and  the  corresponding  ligaments.  External. — External  vena 
comes,  dorsalis  pedis  nerve,  innermost  tendon  of  the  extensor  longus 
digitorum,  and,  near  its  termination,  the  innermost  tendon  of  the 
extensor  brevis  digitorum  as  it  is  about  to  cross  the  artery. 
Internal. — Internal  vena  comes,  tendon  of  the  extensor  proprius 
hallucis,  and,  near  its  termination,  the  innermost  tendon  of  the 
extensor  brevis  digitorum  after  it  has  crossed  the  vessel. 

The  artery  is  firmly  bound  down  by  connective  tissue  to  the 
subjacent  bones  and  ligaments.  It  is  accompanied  by  two  verise 
comites,  one  on  either  side,  which  communicate  with  each  other  by 
transverse  branches  lying  superficial  to  the  vessel,  and  ultimately 
become  the  vense  comites  of  the  anterior  tibial  artery. 

Branches. — The  branches  are  as  follows  :  internal  tarsal, 
external  tarsal,  metatarsal,  arteria  dorsalis  hallucis  or  first  dorsal 


THE  LOWER  LIMB 


483 


interosseous,  and  plantar  or  perforating,  which  latter  divides  in 
the  sole  of  the  foot  into  arteria  magna  or  princeps  hallucis,  or 
first  plantar  interosseous,  and  plantar  communicating,  which  latter 
completes  the  plantar  arch. 

The  internal  tarsal  arteries  are  two  or  three  in  number,  and 
supply  the  adjacent  structures  on  the  inner  border  of  the  foot, 
where   they  anastomose  with   branches   of   the    internal    plantar 


Anterior  Peroneal  Artery 

External  Malleolar  Artery 

External  Malleolus 


Tarsal  Arterj__ 


Metatarsal  Artery^ 


Posterior  Perforating. 
Artery 
Second,  Third,  and. 
Fourth  Dorsal 
Interosseous  Arteries 


Anterior  Tibial  Artery 
Internal  Malleolar  Artery 

_  Internal  Malleolus 


-Tibialis  Anticus 
.  Dorsalis  Pedis  Artery 

-Internal  Tarsal  Arteries 


Plantar  Branch  of  Dor- 
salis Pedis  Artery 
First  Dorsal  Interosseous 
Artery 


Anterior  Perforating 
Artery 


Fig.  239. — The  Arteries  on  the  Dorsum  of  the  Right  Foot 
(after  L.  Testut's  'Anatomie  Humaine'). 

artery.      The   highest   of    them    also   takes    part  in    the   internal 
malleolar  anastomosis. 

The  external  tarsal  artery  passes  outwards  beneath  the  extensor 
brevis  digitorum.  It  su])i)lies  the  adjacent  structures,  and  at  the 
outer  border  of  the  foot  it  anastomoses  with  the  metatarsal  and 
external  plantar  arteries.  It  also  takes  part  in  the  external  malleolar 
anastomosis. 

31—2 


484  A  MANUAL  OF  ANATOMY 

The  metatarsal  artery  arises  on  a  level  with  the  bases  of 
the  metatarsal  bones,  over  which  it  passes  on  its  way  to  the  outer 
border  of  the  foot,  being  under  cover  of  the  extensor  brevis 
digitorum.  At  the  outer  border  it  anastomoses  with  the  tarsal 
and  external  plantar  arteries.  The  vessel  forms  a  slight  arch 
with  the  convexity  directed  forwards.  From  the  concavity  of 
the  arch  a  few  recurrent  branches  are  given  off  to  the  tarsal 
articulations.  From  the  convexity  three  dorsal  interosseous 
arteries  are  given  off,  which  pass  forwards  over  the  outer  three 
interosseous  spaces.  At  the  level  of  the  metatarso-phalangeal 
joints  each  divides  into  two  dorsal  collateral  digital  arteries,  which 
supply  the  contiguous  sides  of  the  second  and  third,  third  and 
fourth,  and  fourth  and  fifth  toes.  The  most  external  dorsal  inter- 
osseous artery,  before  it  divides  into  its  two  collateral  branches, 
furnishes  a  single  dorsal  digital  artery  to  the  outer  side  of  the  fifth 
or  little  toe.  At  the  proximal  end  of  the  second,  third,  and  fourth 
interosseous  spaces  the  three  dorsal  interosseous  arteries  (in  them- 
selves small)  are  reinforced  each  by  a  posterior  perforating  artery, 
the  three  posterior  perforating  arteries  being  branches  of  the  plantar 
arch.  At  the  distal  end  of  these  interosseous  spaces  the  three 
dorsal  interosseous  arteries  are  usually  further  reinforced  each  by 
an  anterior  perforating  artery,  the  three  anterior  perforating  arteries 
being  branches  of  the  three  compound  plantar  digital  arteries  from 
the  plantar  arch. 

The  arteria  dorsalis  hallucis  is  the  first  dorsal  interosseous  artery. 
Arising  from  the  terminal  part  of  the  dorsalis  pedis  artery,  it 
continues  the  direction  of  that  vessel,  and  passes  forwards  over 
the  first  interosseous  space.  On  reaching  the  cleft  between  the 
great  toe  and  the  second  it  divides  into  two  dorsal  collateral  digital 
branches  for  the  supply  of  the  contiguous  sides  of  these  two  toes, 
and  it  furnishes  a  small  single  dorsal  digital  artery  for  the  supply 
of  the  inner  side  of  the  great  toe.  The  dorsalis  hallucis  artery  is 
not  reinforced  by  any  posterior  perforating  branch.  Before,  how- 
ever, dividing  into  its  digital  branches  it  receives  an  anterior  per- 
forating artery,  which  is  derived  from  the  arteria  magna  or  princeps 
hallucis  in  the  sole. 

The  dorsal  digital  arteries  as  they  pass  along  the  sides  of  the  toes 
communicate  with  each  other  across  their  dorsal  aspects,  and  also 
with  the  corresponding  plantar  digital  arteries. 

The  plantar  or  perforating  artery  will  be  described  in  connection 
with  the  sole  of  the  foot. 

Varieties  of  Dorsalis  Pedis  Artery — i.  Origin. — The  vessel  may  be  the  con 
tinuation  of  the  anterior  peroneal  artery. 

2.  Course. — The  vessel  often  describes  a  considerable  curve  outwards  before 
it  reaches  the  proximal  end  of  the  first  interosseous  space.  In  these  cases 
the  artery  may  terminate  at  the  back  of  the  second  interosseous  space  instead 
of  the  first. 

3.  Branclies. — There  is  considerable  deviation  from  the  normal  in  respect 
of  branches.  The  branch  most  affected  is  the  metatarsal  artery.  This  may 
arise  in  common  with  the  tarsal  branch.     The  metatarsal  arch  is  often  very 


THE  LOWER  LIMB 


48s 


indefinite.  The  metatarsal  artery  is  sometimes  absent,  and  when  this  occurs 
the  dorsal  interosseous  arteries  of  the  outer  three  interosseous  spaces  are 
usually  furnished  by  the  three  posterior  perforating  arteries  from  the  plantar 
arch,  or.  it  may  be.  l)y  the  tarsal  artery. 

Dorsalis  Pedis  Nerve. — This  nerve  is  the  continuation  of  the 
anterior  tibial.  It  commences  at  the  anterior  hgament  of  the 
ankle-joint,  and  terminates  at  the  distal  end  of  the  first  inter- 
osseous space  by  dividing  into  two  dorsal  collateral  digital  nerves 


Peroneus  Bievis 
Peroneus  Lonsius 


E.\  tensor  Longus  Digitorum 
E.\t.  Malleolar  Anastomosis 


Peroneus  Tertius  -- 


>retatarsal  Arti 


Musculo-cutaneous  Nerve 


Upper  Band  of  Anterior 
Annular  Ligament 


E.\tensor  Proprius  Hallucis 
Tibialis  Anticus 


Lower  Band  of  Anterior 
Annular  Ligament 


External  Branch  of  Dorsalis 

Pedis  Nerve 
Extensor  Brevis  Digitorum 
Liternal  Tarsal  Arteries 

Dorsalis  Pedis  Nerve 
Dorsalis  Pedis  Artery 


Communicating  Branch  between 
Musculo-cutaneous  and 
Dorsalis  Pedis  Nerves 


First  Do 


Fig.  240. — Dissection  of  the  Dorsum  of  the  Right  Foot. 

for  the  supply  of  the  contiguous  sides  of  the  great  toe  and  the 
second.  Its  relations  correspond  with  those  of  the  dorsalis  pedis 
artery,  on  the  outer  side  of  which  it  lies,  with  the  intervention  of  the 
external  vena  comes.  As  the  nerve  passes  over  the  dorsal  asjiect 
of  the  first  interosseous  space  it  is  reinforced  by  an  offset  from  the 
inner  branch  of  the  internal  division  of  the  musculo-cutaneous 
nerve. 


486 


A  MANUAL  OF  ANATOMY 


Branches. — The  branches  are  as  follows  :  external  or  tarsal, 
interosseous,  and  terminal. 

The  external  or  tarsal  branch  arises  from  the  dorsalis  pedis 
nerve  as  soon  as  it  emerges  from  beneath  the  lower  division  of 
the  anterior  annular  ligament.  It  passes  outwards  beneath  the 
extensor  brevis  digitorum,  and  in  that  situation  it  presents  a 
gangliform  enlargement  from  which  branches  are  furnished  to  the 
extensor   brevis   digitorum    and   the   tarsal   articulations.      Three 

interosseous  branches  also  arise  from  it, 
which  pass  over  the  dorsal  aspects  of  the 
three  outer  interosseous  spaces,  supply- 
ing the  adjacent  tarso-metatarsal  and 
metatarso-phalangeal  articulations.  The 
interosseous  branch,  which  lies  over  the 
second  interosseous  space,  usually  sup- 
plies a  small  twig  to  the  dorsal  inter- 
osseous muscle  of  that  space. 

The  interosseous  branch  passes  over 
the  dorsal  aspect  of  the  first  interosseous 
space,  supplying  the  adjacent  tarso-meta- 
tarsal and  metatarso-phalangeal  articula- 
tions. It  also  gives  a  twig  to  the  first 
dorsal  interosseous  muscle. 

The  terminal  branches  are  the  dorsal 
collateral  digital  nerves  for  the  con- 
tiguous sides  of  the  great  toe  and  the 
second. 

Dorsal  Venous  Arch. — This  arch  is 
superficial  to  the  deep  fascia,  and  is 
situated  well  forward  upon  the  dorsum 
of  the  foot,  being  about  2  inches  from 
the  webs  of  the  toes.  The  convexity  of 
the  arch,  which  is  but  slight,  is  directed 
forwards.  It  receives  (i)  the  dorsal 
digital  veins,  (2)  small  veins  from  the 
dorsum  of  the  foot,  and  (3)  the  efferent 
interdigital  veins  which  come  from  the 
plantar  transverse  venous  arch  situated 

Pj(3._  241. The  External    ^^^.r  the   clefts  of   the   toes.     The  blood 

Saphenous  Vein  and  its     is  carried  away  from  the  dorsal  venous 
Tributaries.  arch  by  the  two  saphenous  veins.     The 

internal  or  long  saphenous  vein  arises 
from  the  inner  end  of  the  arch,  and,  having  received  branches 
from  the  superficial  plantar  venous  plexus  which  turn  round  the 
inner  border  of  the  foot,  it  passes  in  front  of  the  internal  malleolus, 
and  thus  reaches  the  inner  side  of  the  leg.  Its  further  course  has 
been  previously  described. 

The  external  or  short  saphenous  vein  arises  from  the  outer  end 
of  the  arch,  and,  having  received   branches  from  the  superficial 


THE  LOWER  LIMB  487 

plantar  venous  plexus  which  turn  round  the  outer  border  of  the 
foot,  it  passes  below  and  behind  the  external  malleolus,  and 
thus  reaches  the  back  of  the  leg.  It  then  passes  upwards  and 
inwards,  lying  at  first  to  the  outer  side  of  the  tendo  Achillis.  On 
reaching  the  middle  line  of  the  calf,  it  ascends  in  the  groove  between 
the  two  heads  of  the  gastrocnemius  until  it  arrives  at  the  interval 
between  the  condyles  of  the  femur.  Up  to  this  point  the  vein  is 
superficial  to  the  deep  fascia.  It  now,  however,  passes  through 
an  opening  in  that  fascia,  and  terminates  in  the  popliteal  vein. 
As  high  as  the  centre  of  the  calf  the  vein  is  accompanied  by  the 
short  saphenous  nerve,  which  lies  on  its  outer  side.  From  the 
centre  of  the  calf  up  to  where  the  vein  pierces  the  deep  fascia  it 
is  accompanied  by  the  terminal  part  of  the  small  sciatic  nerve  and 
the  middle  superficial  or  cutaneous  sural  artery.  It  receives 
many  tributaries  from  the  calcaneal  region,  and  from  the  outer 
and  back  parts  of  the  leg,  and  it  communicates  at  intervals  with 
the  venae  comites  of  the  posterior  tibial  and  peroneal  arteries. 
Just  before  it  pierces  the  deep  fascia  a  communicating  branch 
passes  upwards  and  inwards  from  it  to  join  the  long  saphenous 
vein.  The  external  or  short  saphenous  vein  is  provided  with  about 
ten  valves. 

External  Aspect  of  the  Leg. 

In  this  region  the  lateral  cutaneous  branch  of  the  external  pop- 
liteal nerve  is  met  with.  It  supplies  the  integument  of  the  outer 
side  of  the  leg  over  about  its  upper  two-thirds,  as  well  as  the  adjacent 
integument  of  the  sural  region. 

Muscles.  Peroneus  Longus — Origin. — (i)  The  external  aspect 
of  the  head  of  the  fibula  ;  (2)  the  adjacent  part  of  the  external 
tuberosity  of  the  tibia;  (3)  the  upper  two-thirds  of  the  external 
surface  of  the  shaft  of  the  fibula ;  (4)  the  antero-external  and 
postero-external  intermuscular  septa;  and  (5)  the  deep  fascia. 

Insertion. — ^The  tendon  of  insertion  divides  into  two  parts.  The 
main  part  is  inserted  into  the  outer  side  of  the  tuberosity  on  the 
plantar  surface  of  the  base  of  the  first  metatarsal  bone,  and  the  other 
into  the  lower  and  anterior  part  of  the  outer  surface  of  the  internal 
cuneiform  bone. 

Nerve-supply. — The  musculo-cutaneous  nerve. 

Action. — (i)  To  extend  the  foot  upon  the  leg  ;  (2)  to  abduct  or 
turn  out  the  fore  part  of  the  foot  ;  (3)  to  depress  the  inner  border 
of  the  foot,  the  effect  of  which  is  to  raise  the  outer  border  and 
produce  eversion  of  the  sole  ;  and  (4)  to  supj^ort  and  strengthen 
the  transverse  arch  of  the  foot. 

The  tendon  descends  behind  that  of  the  peroneus  brevis,  and, 
along  with  it,  passes  through  the  groove  behind  the  external  mal- 
leolus and  beneath  the  external  annular  ligament,  the  two  tendons 
having  one  synovial  sheath  in  common.  After  leaving  the  malleolar 
groove,  the  tendon  j)asses  forwards  on  the  outer  surface  of  the  os 


488  A  MANUAL  OF  ANATOMY 

calcis,  where  it  occupies  the  groove  below  the  peroneal  spine  or 
ridge.  In  this  part  of  its  course  the  tendon  is  surrounded  by  a 
fibrous  sheath,  which  is  derived  froih  the  lower  border  of  the 
external  annular  ligament,  and  it  is  here  invested  by  a  special 
S5movial  sheath,  which  is  a  prolongation  of  that  beneath  the  external 
annular  ligament.     It  then  turns  round  the  peroneal  notch  on  the 


External  Popliteal  Nerve 

Tendon  of  Biceps 


Long  External  Lateral 
Ligament 


Gastrocnemius 


Soleus 


Peroneus  Longus . 
Peroneus  Brevis. 


Tendo  Achillis, 


Extensor  Proprius  Hallucis 
Extensor  Longus  Digitorum 
Peroneus  Tertius 

Upper  Division  of  Ant.  Annular  Ligament 

.Lower  Division  of  Ant.  Annular  Lig. 

Extensor  Brevis  Digitorum 

Tendon  of  Peroneus  Tertius 


Fig.  242. — Muscles  of  the  Leg  (External  View). 

outer  border  of  the  cuboid,  and  traverses  the  peroneal  groove  on 
the  plantar  surface  of  that  bone,  which  is  converted  into  a  fibro- 
osseous  canal  by  an  expansion  derived  from  the  long  plantar 
hgament.  Finally,  after  leaving  this  fibro-osseous  canal,  in  which 
it  is  invested  by  a  special  synovial  sheath,  the  tendon  crosses  the 
sole  of  the  foot  to  its  twofold  insertion,  taking  a  direction  forwards 


THE  LOWER  LIMB  489 

and  inwards.     In  that  part  of  the  tendon  which  turns  round  the 
outer  border  of  the  cuboid  a  sesamoid  fibro-cartilage  is  found. 

Peroneus  Brevis — Origin. — (i)  The  lower  two- thirds  of  the  ex- 
ternal surface  of  the  shaft  of  the  fibula,  except  the  last  2  inches  ; 

(2)  the  antero-external  and  postero-external  intermuscular  septa  ; 
and  (3)  the  deep  fascia. 

Insertion. — The  tuberosity  on  the  outer  side  of  the  base  of  the 
fifth  metatarsal  bone.  From  the  tendon  of  insertion  a  slip  is  often 
given  to  the  long  extensor  tendon  of  the  little  toe. 

Nerve-supply. — The  musculo-cutaneous  nerve. 

Action. — (i)  To  extend  the  foot  upon  the  leg,  but  in  a  feeble 
manner  ;  (2)  to  abduct  or  turn  out  the  fore  part  of  the  foot  ;  and 

(3)  to  raise  directly  the  outer  border  of  the  foot,  thus  producing 
aversion  of  the  sole. 

The  middle  third  of  the  external  surface  of  the  fibula  is  occupied 
by  both  peroneus  longus  and  peroneus  brevis,  the  former  arising 
from  the  posterior  half,  and  the  latter  from  the  anterior  half,  so 
that  the  two  muscles  overlap.  The  tendon  of  the  peroneus  brevis 
passes  through  the  groove  behind  the  external  malleolus  with  the 
tendon  of  the  peroneus  longus,  which  is  directly  behind  it.  Both 
tendons  lie  beneath  the  external  annular  ligament,  where  they  have 
one  synovial  sheath  in  common.  After  leaving  the  malleolar 
groove  the  tendon  of  the  peroneus  brevis  passes  forwards  on  the 
outer  surface  of  the  os  calcis,  where  it  occupies  the  groove  above 
the  peroneal  spine  or  ridge.  In  this  part  of  its  course  the  tendon 
is  surrounded  by  a  fibrous  sheath,  which  is  derived  from  the  lower 
border  of  the  external  annular  ligament,  and  it  is  here  invested  by 
a  special  synovial  sheath,  which  is  a  prolongation  of  that  beneath 
the  external  annular  ligament.  After  leaving  the  outer  surface 
of  the  OS  calcis  the  tendon  passes  over  the  cuboid  bone,  and  so  reaches 
its  insertion. 

On  the  outer  surface  of  the  os  calcis  the  two  peroneal  tendons  are 
completely  separated  from  each  other,  that  of  the  brevis  being 
above  that  of  the  longus.  The  separation  is  effected  partly  by  a 
strong  fibrous  septum,  and  partly  by  the  peroneal  spine  or  ridge. 
The  peroneus  longus  and  peroneus  brevis  are  contained  in  a  fibro- 
osseous  canal  formed  by  the  deep  fascia,  the  intermuscular  septum 
on  each  side,  and  the  external  surface  of  the  shaft  of  the  fibula. 


Posterior  Aspect  of  the  Leg. 

Superficial  Structures, — The  following  su}:)erficial  structures  are 
met  with  in  this  region  :  the  external  or  short  saphenous  vein, 
the  cutaneous  sural  branches  of  the  popliteal  artery,  the  terminal 
part  of  the  small  sciatic  nerve,  the  ramus  communicans  tibialis 
nerve,  the  ramus  communicans  fibularis  nerve,  and  the  external 
or  short  saphenous  nerve.  These,  except  the  last  named,  have  been 
already  described. 


490  A  MANUAL  OF  ANATOMY 

External  or  Short  Saphenous  Nerve. — This  nerve  is  formed  by 
the  union  of  the  ramus  communicans  tibiahs  of  the  internal  pop- 
hteal  and  the  ramus  communicans  fibularis  of  the  external  pop- 
liteal. The  union  takes  place  at,  or  just  below,  the  centre  of  the 
calf,  and  superficial  to  the  deep  fascia.  The  nerve  descends  on  the 
outer  side  of  the  short  saphenous  vein,  and  external  to  the  tendo 
Achillis.  It  then  passes  behind  and  below  the  external  malleolus, 
and  so  reaches  the  outer  border  of  the  foot,  along  which  it  passes 
to  the  outer  side  of  the  little  toe,  of  which  it  is  the  dorsal  digital 
nerve.  The  nerve  supplies  the  integument  of  the  back  of  the  leg 
in  its  lower  half,  the  external  malleolar  region,  the  outer  side  cf 
the  calcaneum,  and  the  outer  border  of  the  foot  and  outer  side  of 
the  little  toe.  It  also  furnishes  articular  branches  to  the  ankle- 
joint,  and  the  astragalo-calcaneal  articulation. 

Muscles. — The  muscles  of  the  back  of  the  leg  are  divided  into  two 
groups — superficial  and  deep. 

Superficial  Group. — This  group  comprises  the  gastrocnemius, 
soleus,  and  plantaris,  which  are  collectively  called  the  sural  (calf) 
muscles. 

Gastrocnemius. — This  muscle  is  so  named  because  it  forms  the 
'  belly  of  the  leg,'  that  is  to  say,  the  fleshy  enlargement  at  the 
back  of  the  leg  which  is  called  the  calf. 

Origin. — ^The  external  head  arises  from  (i)  the  outer  surface  of  the 
external  condyle  of  the  femur  immediately  above  the  commence- 
ment of  the  popliteal  groove,  and  close  behind  and  above  the 
external  tuberosity  ;  and  (2)  the  adjacent  part  of  the  posterior 
surface  of  the  femur,  vertically,  for  at  least  an  inch  immediately 
external  to  the  lower  part  of  the  external  supracondylar  ridge. 
The  internal  head  arises  from  (i)  an  oblique  impression  on  the 
posterior  surface  of  the  femur  immediately  above  the  internal 
condyle,  and  extending  inwards  for  fully  an  inch  as  far  as  the 
adductor  tubercle  ;  and  (2)  the  lower  extremity  of  the  internal 
supracondylar  ridge  for  a  short  distance. 

Insertion. — ^The  fleshy  part  of  the  muscle  gives  place  to  a  flat 
tendon,  which  joins  the  subjacent  tendon  of  the  soleus  at  the 
centre  of  the  leg  to  form  the  tendo  Achillis.  Through  this  latter 
the  gastrocnemius  is  inserted  into  the  middle  zone  on  the  posterior 
surface  of  the  tuber  calcis,  a  bursa  intervening  between  the  tendon 
and  the  upper  zone. 

Nerve-supply. — ^The  internal  popliteal  nerve,  which  furnishes  two 
branches,  one  for  each  head. 

Action. — Acting  from  its  origin,  the  muscle  is  a  powerful  extensor 
of  the  foot  upon  the  leg,  thus  raising  the  heel.  Acting  from  its 
insertion,  as  when  the  ankle-joint  is  fixed  by  the  muscles  of  the 
anterior  aspect  of  the  leg,  the  gastrocnemius  is  a  flexor  of  the 
knee-joint. 

The  two  heads  come  into  contact  at  the  jimction  of  the  upper 
sixth  and  lower  five-sixths  of  the  leg,  and  so  they  limit  the  lower 
part  of  the  popliteal  space.     After  coming  together  they  are  sepa- 


THE  LOWER  LIMB  491 

rated  superficially  by  a  longitudinal  groove,  and  when  the  lips  of 
this  groove  are  held  apart  a  tendinous  band  or  raphe  is  seen  to  lie 
between  them.  The  fleshy  fasciculi  of  both  heads  are  short  and 
oblique,  and  they  terminate  upon  the  lower  tendon,  which  extends 
upwards  upon  the  deep  or  anterior  surface  of  the  muscle  in  the  form 
of  an  expanded  aponeurosis.  The  shortness  of  the  fleshy  bundles 
gives  the  muscle  great  power  of  action,  but  the  range  of  movement 
is  limited. 

The  internal  head  is  separated  from  the  tendon  of  the  semimem- 
branosus by  a  large  bursa,  called  the  popliteal  bursa,  which  fre- 
quently (one  in  five)  communicates  with  the  synovial  membrane 
of  the  knee-joint.  Another  small  bursa  is  situated  a  little  higher, 
between  the  internal  head  and  the  posterior  surface  of  the  femur. 
In  the  external  head  a  sesamoid  fibro-cartilage  is  occasionally  met 
with. 

Soleus. — ^This  flat  muscle  has  been  so  named  from  its  resemblance 
to  a  sole-fish. 

Origin. — (i)  The  posterior  surface  of  the  head,  and  the  upper 
third  of  the  posterior  surface  of  the  shaft,  of  the  fibula  ;  (2)  the 
postero-external  intermuscular  septum  ;  (3)  the  fibrous  arch 
thrown  over  the  popliteal  vessels  and  internal  popliteal  nerve  ; 
(4)  the  oblique  or  popliteal  line  of  the  tibia  ;  and  (5)  the  internal 
border  of  the  tibia  over  its  middle  third. 

Insertion. — The  tendon  joins  that  of  the  gastrocnemius  at  the 
centre  of  the  leg  to  form  the  tendo  AchiUis,  which  is  inserted  into 
the  middle  zone  on  the  posterior  surface  of  the  tuber  calcis. 

Nerve-supply. — (i)  The  internal  popliteal  nerve,  the  branch  from 
which  enters  the  muscle  on  its  superficial  or  posterior  surface  near 
the  upper  border  ;  and  (2)  the  posterior  tibial  nerve,  the  branch 
from  which  enters  the  muscle  on  its  deep  or  anterior  surface  near 
the  centre  of  the  leg. 

Action. — Acting  from  its  origin  the  muscle  is  a  powerful  extensor 

of  the  foot  upon  the  leg,  thus  raising  the  heel.     Acting  from  its 

insertion,  as  when  the  ankle-joint  is  fixed  by  the  muscles  of  the 

anterior  aspect  of  the  leg,  the  soleus  steadies  the  leg  upon  the  foot. 

The  fasciculi  of  this  muscle  are  short  and  oblique,  like  those  of 

the  gastrocnemius.     It  has  therefore  great  power  of  action,  but  its 

range  of  movement   is  limited.      Only  a  limited  number  of  the 

fibres  of  the  soleus  spring  directly  from  the  bony  surfaces.     The 

majority  arise  from  two  aponeurotic  laminae,   which  are  almost 

entirely  concealed  within  the  muscle,  and  which  descend,  one  from 

the  fibula,  and  the  other  from  the  oblique  line  of  the  tibia  and  the 

fibrous  arch  over   the   popliteal  vessels.     The  fibres  which  arise 

from  the  anterior  surfaces  of  these  two  laminae  terminate  upon  a 

median  tendinous  band  or  raphe,  which  is  deeply  i)laced,  and  those 

arising  from  their  posterior  surfaces  end  upon  a  broad  exi)anded 

aponeurosis,  which  covers  the  superficial  or  })osterior  surface  of 

the  muscle,  giving  it  an  appearance  similar  to  that  of  the  deep 

or   anterior   surface   of    the   gastrocnemius.     This   aponeurosis   is 


492  A  MANUAL  OF  ANATOMY 

simply  an  upward  expansion  of  the  tendon  of  insertion  of  the 
muscle. 

Tendo  AcMilis.*  —  This  very  strong  tendon  is  formed  by  the 
union  of  the  tendons  of  the  gastrocnemius  and  soleus.  It  extends 
from  the  centre  of  the  leg  to  the  prominence  of  the  heel,  and  is 
inserted  into  the  middle  zone  on  the  posterior  surface  of  the 
tuber  calcis,  a  bursa  intervening  between  it  and  the  upper  zone. 
The  tendo  Achillis  is  at  first  broad  and  comparatively  thin.  As 
it  descends,  it  becomes  narrower  and  thicker  until  it  reaches 
a  point  about  i|  inches  above  the  tuber  calcis,  beyond  which  it 
again  broadens  to  its  insertion.  The  short  saphenous  vein  and 
nerve  lie  on  its  outer  side,  the  tendon  of  the  plantaris  and  the 
posterior  tibial  vessels  and  nerve  on  the  inner  side,  and  a  large 
quantity  of  fat  beneath  it. 

Plantaris — Origin. — (i)  The  lower  2  inches  of  the  external 
supracondylar  ridge  of  the  femur,  internal  to  the  external  head  of 
the  gastrocnemius;  and  (2)  the  adjacent  part  of  the  posterior 
ligament  of  the  knee-joint. 

Insertion. — The  middle  zone  on  the  posterior  surface  of  the 
tuber  calcis  immediately  to  the  inner  side  of  the  tendo  Achillis, 
with  which  it  is  closely  connected.  It  may,  however,  terminate 
upon  the  inner  border  of  the  tendo  Achillis,  m  the  deep  fascia  of 
the  leg,  upon  the  internal  annular  ligament,  or  in  the  plantar 
fascia. 

Nerve-supply. — ^The  internal  popliteal  nerve. 

Action. — (i)  The  plantaris  acts  as  a  very  weak  auxiliary  to  the 
gastrocnemius.  (2)  From  its  connection  with  the  posterior  liga- 
ment of  the  knee-joint  the  muscle  has  a  slight  action  as  a  retractor 
of  that  ligament  during  flexion  of  the  joint,  and  thus  it  guards  the 
ligament  against  being  nipped  or  pressed  upon  by  the  articular 
surfaces  of  the  femur  and  tibia. 

The  fleshy  belly  of  the  muscle  is  limited  to  the  upper  sixth. 
The  tendon  is  very  narrow  and  remarkably  long,  being  the  longest 
tendon  in  the  body.  It  is  also  very  extensible,  so  that  when  grasped 
by  the  fingers  and  stretched  laterally  it  can  be  drawn  out  into  a 
ribbon  of  about  2  inches  in  breadth. 

The  plantaris,  which  is  sometimes  absent,  is  a  vestigial  muscle,  being  the 
crural  remains  of  a  superficial  flexor  of  the  toes,  the  plantar  portion  of  the 
tendon  of  which,  having  been  divorced,  remains  persistent  as  the  central 
division  of  the  plantar  fascia.  The  homologue  of  the  plantaris  in  the  upper 
hmb  is  the  palmaris  longus. 

Deep  Group. — ^The  muscles  which  comprise  this  group  are  four 
in  number,  namely,  the  popliteus,  flexor  longus  digitorum,  tibialis 
posticus,  and  flexor  longus  hallucis.  The  popliteus  muscle  is 
covered  by  the  popliteal  fascia,  which  is  one  of  the  modes  of  inser- 
tion of  the  semimembranosus.     The  other  muscles,  together  with 

*  Being  inserted  into  the  heel,  it  has  been  called  the  tendo  Achillis,  because 
it  was  believed  that  the  heel  was  the  only  part  in  which  the  Greek  hero,  Achilles, 
could  be  wounded. 


THE  LOWER  LIMB  493 

the  posterior  tibial  vessels  and  nerve,  are  covered  by  the  posterior 
or  transverse  intermuscular  septum. 

Popliteus — Origin. — (i)  By  a  narrow  round  tendon  from  the 
front  part  of  the  horizontal  portion  of  the  popliteal  groove  on  the 
outer  surface  of  the  external  condyle  of  the  femur,  and  (2)  slightly 
from  the  posterior  ligament  of  the  knee-joint. 

Insertion. — (i)  The  popliteal  surface  of  the  tibia,  and  (2)  the 
popliteal  fascia  which  covers  the  muscle. 

Nerve-siipplv. — The  internal  popliteal  nerve.  The  branch  from 
this  nerve  descends  over  the  posterior  surface  of  the  muscle,  and, 
turning  round  its  lower  border,  enters  the  deep  or  anterior  surface 
in  its  lower  part. 

Action. — The  muscle  is  a  feeble  flexor  of  the  leg  upon  the  thigh, 
and,  when  the  knee-joint  has  been  flexed,  it  acts  as  an  internal 
rotator  of  the  leg. 

The  tendon  of  origin  is  within  the  capsular  ligament,  and  beneath 
the  long  external  lateral  ligament,  of  the  knee-joint.  Whilst  within 
the  joint  it  is  in  contact  with  the  posterior  and  outer  aspect  of  the 
external  semilunar  fibro-cartilage,  which  it  grooves.  It  then 
pierces  the  capsule,  and  the  fleshy  fibres  spread  out  in  the  manner 
of  a  fan  as  they  diverge  downwards  and  inwards.  The  popliteal 
fascia,  which  covers  the  muscle,  represents  part  of  the  insertion  of 
the  semimembranosus  muscle,  and  it  is  attached  to  the  oblique  or 
popliteal  line  of  the  tibia. 

Flexor  Longus  Digitorum  (flexor  perforans) — Origin. — (i)  The 
inner  division  of  the  posterior  surface  of  the  shaft  of  the  tibia, 
commencing  at  the  oblique  or  popliteal  line,  and  extending  down- 
wards over  the  middle  two-fourths  of  the  bone  ;  (2)  the  posterior 
intermuscular  septum  which  covers  the  muscle  ;  and  (3)  the  inter- 
muscular septum  between  it  and  the  tibialis  posticus  on  its  outer 
side. 

Insertion. — By  means  of  four  tendons  which  go  to  the  four  outer 
toes,  where  each  is  inserted  into  the  plantar  surface  of  the  base  or 
proximal  end  of  the  distal  phalanx. 

Nerve-supply. — The  posterior  tibial  nerve. 

Action. — (i)The  muscle  acts  as  a  flexor  of  the  distal  phalanges 
of  the  four  outer  toes,  and  (2)  when  these  have  been  flexed,  it  acts 
as  an  extej|isor  of  the  foot  upon  the  leg. 

The  muscle  crosses  behind  the  tibialis  posticus  obliquely  from 
within  outwards  in  the  lower  third  of  the  leg.  The  tendon  passes 
behind  the  internal  malleolus  and  beneath  the  internal  annular 
ligament,  lying  behind  and  slightly  external  to  the  tendon  of  the 
tibialis  posticus,  and  occupying  a  special,  })urely  fibrous  compart- 
ment, in  which  it  is  invested  by  a  distinct  synovial  sheath.  It 
then  enters  the  sole  of  the  foot,  where  it  jjasses  forwards  and  out- 
wards to  the  middle  line,  crossing  beneath  the  tendon  of  the  flexor 
longus  hallucis,  from  which  it  receives  a  slij).  On  reaching  the 
middle  line  it  gives  insertion  to  the  flexor  or  musculus  accessorius, 
and  immediately  afterwards  it  divides  about  the  centre  into  four 


494  A   MANUAL  OF  ANATOMY 

tendons  which,  after  having  given  origin  to  the  four  lumbricales 
muscles,  go  to  the  four  outer  toes.  Each  tendon,  as  it  passes  along 
the  plantar  surface  of  a  toe,  has  a  tendon  of  the  flexor  brevis 
digitorum  lying  close  beneath  it  as  far  as  the  second  phalanx, 
the  two  tendons  occupying  a  fibro-osseous  canal  lined  by  a  synovial 
membrane,  which  furnishes  a  separate  investment  to  each  tendon. 
Opposite  the  first  phalanx  the  brevis  tendon  divides  into  two  parts, 
and  the  longus  tendon  passes  through  the  cleft  thus  formed  (hence 
the  name  flexor  perforans)  on  its  way  to  the  distal  phalanx.  The 
fibro-osseous  canals  and  their  synovial  membranes,  with  the  vincula' 
accessoria  tendinum  of  the  latter,  namely,  ligamenta  brevia  and 
ligamenta  longa,  correspond  with  those  of  the  fingers. 

In  the  leg  the  muscle  occupies  a  fibro-osseous  canal  formed  by 
intermuscular  septa  and  the  posterior  surface  of  the  shaft  of  the 
tibia. 

Tibialis  Posticus — Origin. — (i)  The  outer  division  of  the  posterior 
surface  of  the  shaft  of  the  tibia,  extending  as  high  as  the  commence- 
ment of  the  oblique  or  popliteal  line,  and  ceasing  just  below  the 
centre  of  the  bone  ;  (2)  the  posterior  surface  of  the  interosseous 
membrane,  except  the  lower  2  inches  ;  (3)  the  internal  surface  of 
the  shaft  of  the  fibula  ;  (4)  the  posterior  or  transverse  intermuscular 
septum,  as  it  covers  the  muscle  ;  and  (5)  the  intermuscular  septa 
on  either  side,  separating  it  from  the  flexor  longus  digitorum 
internally  and  the  flexor  longus  hallucis  externally. 

Insertion. — ^The  tuberosity  of  the  navicular  or  scaphoid  bone. 
From  this  insertion  eight  expansions  are  given  off.  One  passes 
backwards  to  the  anterior  part  of  the  under  surface  of  the  susten- 
taculum tali  of  the  os  calcis.  The  other  seven  pass  forwards,  and 
are  attached  as  follows  :  three  to  the  internal,  middle,  and  external 
cuneiform  bones,  one  to  the  cuboid  bone,  and  three  to  the  bases  of 
the  second,  third,  and  fourth  metatarsal  bones,  all  on  their  plantar 
aspects. 

Nerve- supply. — The  posterior  tibial  nerve. 

Action. — (i)  The  muscle  inverts  the  sole  of  the  foot  ;  (2)  it  is  an 
extensor  of  the  foot  upon  the  leg  ;  and  (3)  it  contributes  in  a  material 
degree  to  the  support  of  the  longitudinal  arch  of  the  foot,  and  so 
helps  to  guard  against  the  condition  known  as  flat  foot,  being  in 
this  respect  auxiliary  to  the  inferior  or  internal  calcaneo-navicular 
or  spring  ligament. 

In  the  lower  third  of  the  leg  the  muscle  passes  obliquely  in- 
wards in  front  of  the  flexor  longus  digitorum.  The  tendon  passes 
through  the  groove  behind  the  internal  malleolus,  where  it  is 
beneath  the  internal  annular  ligament,  occupying  one  of  the  fibro- 
osseous  canals,  and  having  the  tendon  of  the  flexor  longus  digi- 
torum (enclosed  within  its  fibrous  canal)  lying  behind  and  slightly 
external  to  it.  In  this  part  of  its  course  the  tendon  has  a  special 
synovial  investment,  which  is  also  prolonged  forwards  around  it 
as  far  as  the  navicular  bone.  As  it  passes  over  the  head  of  the 
astragalus  and  spring  ligament  it  contains  a  sesamoid  fibrocartilage. 


THE  LOWER  LIMB  495 

The  greater  part  of  the  muscle  in  the  leg  is  contained  in  a  fibro- 
osseous  canal  formed  by  the  posterior  or  transverse  intermuscular 
septum,  the  interosseous  membrane,  the  intermuscular  septa  on 
either  side,  and  the  surfaces  of  the  tibia  and  fibula  from  which  it 
arises. 

Flexor  Longus  Hallucis — Origin. — (i)  The  lower  two-thirds  of 
the  posterior  surface  of  the  shaft  of  the  fibula,  except  the  last  inch 
or  more  ;  (2)  the  postero-external  intermuscular  septum,  which 
separates  the  muscle  from  the  peroneus  longus  and  peroneus 
brevis  ;  (3)  the  intermuscular  septum  between  it  and  the  tibialis 
posticus  ;  and  (4)  the  posterior  or  transverse  intermuscular  septum, 
as  it  covers  the  muscle. 

Insertion. — ^The  plantar  surface  of  the  base  of  the  distal  phalanx 
of  the  great  toe. 

Nerve- sup  ply. — The  posterior  tibial  nerve. 

Action. — (i)  The  muscle  acts  as  a  flexor  of  the  distal  phalanx 
of  the  great  toe  ;  (2)  it  is  an  extensor  of  the  foot  upon  the  leg ;  (3)  it 
contributes  to  the  support  of  the  longitudinal  arch  of  the  foot ; 
and  (4)  by  means  of  the  slip  which  it  gives  to  the  tendon  of  the 
flexor  longus  digitorum  in  the  sole  it  is  an  auxiliary  of  that 
muscle,  more  especially  in  flexing  the  second  and  third  toes. 

The  tendon  passes  through  the  groove  on  the  back  of  the  lower 
end  of  the  tibia  at  its  outer  part,  where  it  lies  beneath  the  internal 
annular  ligament,  occupying  one  of  the  fibro-osseous  canals,  and 
having  a  special  synovial  investment.  Beyond  this  point  it  passes 
in  succession  through  the  groove  on  the  posterior  border  of  the 
astragalus,  and  through  that  on  the  under  surface  of  the  sustenta- 
culum tali  of  the  os  calcis.  Each  of  these  grooves  is  converted  into 
a  fibro-osseous  canal  by  a  fibrous  expansion,  and  in  each  case  the 
tendon  has  a  synovial  investment.  In  the  sole  the  tendon  is  crossed 
superficially  or  interiorly,  and  from  within  outwards,  by  that  of 
the  flexor  longus  digitorum,  to  which  it  gives  a  slip.  In  most 
cases  this  slip  is  incorporated  with  the  long  flexor  tendons  of 
the  second  and  third  toes  (Turner).  As  it  passes  along  the  first 
phalanx  it  is  contained  in  a  fibro-osseous  canal  lined  by  synovial 
membrane,  which  also  invests  the  tendon  and  gives  rise  to  a  liga- 
mentum  breve.  In  the  leg  the  flexor  longus  hallucis  is  contained 
within  a  fibro-osseous  canal  formed  by  intermuscular  septa  and 
the  posterior  surface  of  the  shaft  of  the  fibula. 

Posterior  Tibial  Artery. — This  vessel  is  the  larger  of  the  two 
terminal  branches  of  the  po})liteal,  the  other  being  the  anterior 
tibial.  It  commences  at  the  lower  border  of  the  popliteus  muscle 
on  a  level  with  the  lower  border  of  the  tubercle  of  the  tibia, 
fully  i|  inches  below  the  uj)per  surface  of  the  head  of  that  bone, 
and  it  terminates  at  the  lower  border  of  the  internal  annular 
ligament  by  dividing  into  the  internal  and  external  jilantar  arteries. 
The  termination  of  the  vessel  is  situated  midway  between  the 
inner  part  of  the  point  of  the  heel  and  the  tip  of  the  internal 
malleolus.      In    the    ui)j)er    two-thirds    of    the    leg    it    is    deeply 


496 


A  MANUAL  OF  ANATOMY 


Superior  Internal  Articular  Artery, 


Internal  Head  of  Gastrocnemius 

Inferior  Internal  Articular- - 
Artery 

Popliteus-  _ 

Posterior  Tibial  Nerve 

Medullary  Artery  of  Tibia 

Soleus(cut) 


Internal  Popliteal  Nerve 
Popliteal  Artery 


Superior  External  Articular 
Artery 


_  External  Head  of  Gastrocnemius 

-    Plantaris 

--  Inferior  External  Articular 
Artery 

-.  Anterior  Tibial  Artery 
Posterior  Tibial  Artery 
Peroneal  Artery 


Tibialis  Posticv:s J 


Flexor  Longus  Digitorum 


.  Tibialis  Posticus 


.  Peroneus  Longus 


|_  _  Flexor  Longus  Hallucis 


_  Peroneus  Brevis 


Posterior  Tibial  Nerve  ^ 

Posterior  Tibial  Arterj'  _ 

Flexor  Longus  Digitorum 

Tibialis  Posticus 


Flexor  Longus  Hallucis 


Peroneus  Longus 
.  Peroneus  Brevis 

Tendo  Achillis  (reflected) 


Fig.  243. — The  Back  of  the  Right  Leg  (Deep  Dissection). 


THE  LOWER  LIMB 


497 


placed,  being  situated  between  the  superficial  and  deep  muscles, 
and  over  the  interval  between  the  tibia  and  fibula.  It  then  inclines 
inwards,  and  in  the  lower  third  of  the  leg  it  lies  over  the  back  of 
the  tibia  and  to  the  inner  side  of  the  tendo  Achillis,  where  it  is  com- 
paratively superficial.  The  course  of  the  vessel  may  be  indicated 
by  drawing  a  line  from  the  centre  of  the  lower  part  of  the  popliteal 
space  to  a  point  midway  between  the  inner  part  of  the  point  of  the 
heel  and  the  tip  of  the  internal  malleolus. 

Relations — Superficial  or  Posterior. — In  the  upper  two-thirds  the 
vessel  lies  beneath  the  gastrocnemius,  soleus,  and  posterior  or 
transverse  intermuscular  septum  ;  and,  in  the  lower  third,  it  is 
covered  by  the  skin,  superficial  fascia,  deep  fascia,  and  the  internal 
annular  ligament.  Anterior  or  Deep. — ^The  tibialis  posticus  (to 
which  it  is  bound  by  the  posterior  or  transverse  intermuscular 
septum),  flexor  longus  digitorum,  posterior  surface  of  the  tibia,  and 
internal  lateral  ligament  of  the  ankle-joint  (in  this  order  from  above 
downwards).  External. — The  tendo  Achillis  in  the  lower  part  of 
the  leg.  The  artery  in  this  part  of  its  course  lies  about  midway 
between  the  inner  border  of  the  tendo  Achillis  and  the  internal 
border  of  the  tibia.  As  the  vessel  passes  beneath  the  internal 
annular  ligament  it  occupies  a  special  fibro-osseous  canal  along 
with  its  venae  comites  and  the  posterior  tibial  nerve,  the  latter 
being  on  the  outer  side.  In  this  situation  the  tendons  of  the  tibialis 
posticus  and  flexor  longus  digitorum  lie  on  the  inner  side  of  these 
structures,  and  the  tendon  of  the  flexor  longus  hallucis  on  their 
outer  side. 

The  artery  is  accompanied  by  two  venae  comites,  which  closely 
embrace  its  sides,  and  communicate  with  each  other  at  frequent 
intervals  by  transverse  branches  crossing  superficial  to  the  vessel. 
These  venae  comites  ultimately  join  to  form  one  trunk,  which  unites 
with  that  formed  by  the  junction  of  the  venae  comites  of  the 
anterior  tibial  artery  to  form  the  popliteal  vein,  the  union  taking 
place  at  the  lower  border  of  the  popliteus  muscle.  The  posterior 
tibial  nerve  is  at  first  internal  to  the  artery  for  about  ij  inches. 
It  then  crosses  over  the  vessel  just  below  the  origin  of  the  peroneal 
branch,  and  from  this  point  onwards  it  lies  on  its  outer  side. 
Beneath  the  internal  annular  ligament  the  artery  has  frequently 
a  nerve  upon  either  side  of  it,  an  arrangement  which  is  brought 
about  by  an  early  division  of  the  posterior  tibial  nerve  into  its 
internal  and  external  plantar  branches. 

Branches. — These  are  as  follows  :  peroneal,  muscular,  medullary 
or  nutrient,  cutaneous,  communicating,  internal  malleolar,  internal 
calcaneal,  and  terminal. 

The  description  of  the  peroneal  artery,  from  its  large  size  and 
numerous  branchf;s,  will  l)e  deferred  to  the  last. 

The  muscular  branches  are  numerous,  and  are  distributed  to 
the  deej^  group  of  muscles  and  to  the  soleus. 

The  medullary  or  nutrient  artery  is  the  largest  of  all  the  arteries 
bearing  that  name.     Arising  from  the  upper  part  of  the  posterior 

32 


498  A  MANUAL  OF  ANATOMY 

tibial,  it  pierces  the  tibialis  posticus  and  enters  the  medullary 
foramen  of  the  tibia,  accompanied  by  the  medullary  branch  of  the 
nerve  to  the  popliteus. 

The  cutaneous  branches  are  distributed  to  the  integument  of  the 
inner  and  back  part  of  the  leg. 

The  communicating  branch  arises  about  an  inch  above  the  ankle- 
joint.  It  passes  transversely  outwards  between  the  tibia  and  flexor 
longus  hallucis,  and  anastomoses  with  the  communicating  branch 
of  the  peroneal  artery. 

The  internal  malleolar  branches  are  usually  two  in  number. 
Passing  inwards  beneath  the  tendons  of  the  flexor  longus  digitorum 
and  tibialis  posticus,  they  reach  the  front  of  the  internal  malleolus, 
where  they  take  part  in  the  internal  malleolar  anastomosis. 

The  internal  calcaneal  branch  arises  beneath  the  internal  annular 
ligament,  which  it  pierces  near  the  lower  border  to  be  distributed 
over  the  inner  surface  of  the  os  calcis,  where  it  anastomoses 
with  the  internal  calcaneal  branches  of  the  external  plantar 
artery. 

The  terminal  branches  are  the  internal  and  external  plantar 
arteries,  which  will  be  afterwards  described. 

Peroneal  Artery. — ^This  vessel,  which  is  of  large  size,  arises  from 
the  posterior  tibial  fully  i  inch  below  its  commencement.  It  is  at 
first  directed  downwards  and  outwards  over  the  tibialis  posticus 
to  the  back  of  the  fibula.  Having  reached  that  bone,  it  descends 
along  its  posterior  surface  close  to  the  postero-internal  border, 
lying  between  the  bone  and  the  flexor  longus  hallucis,  or  within 
that  muscle,  or  in  a  fibrous  canal  between  that  muscle  and  the 
tibialis  posticus.  About  2  inches  above  the  ankle-joint  it  escapes 
from  beneath  the  flexor  longus  hallucis,  and  divides  into  anterior 
and  posterior  peroneal  arteries. 

Branches. — ^The  branches  are  as  follows  :  muscular,  medullary 
or  nutrient,  cutaneous,  communicating,  and  terminal. 

The  muscular  branches  are  distributed  to  the  adjacent  muscles. 

The  medullary  or  nutrient  artery  enters  the  medullary  foramen  of 
the  fibula. 

The  cutaneous  branches  are  distributed  to  the  integument  on  the 
outer  and  back  part  of  the  leg. 

The  communicating  branch  arises  about  i  inch  above  the  ankle- 
.  joint.  It  passes  transversely  inwards  and  anastomoses  with  the 
communicating  branch  of  the  posterior  tibial  artery. 

The  terminal  branches  are  the  anterior  peroneal  and  posterior 
peroneal. 

The  anterior  peroneal  artery  arises  from  the  peroneal  artery  near 
the  lower  part  of  the  interosseous  membrane,  and  passes  forwards 
through  the  inferior  hiatus  in  it.  Having  reached  the  front  of 
the  leg,  it  descends  under  cover  of  the  peroneus  tertius,  and  takes 
part  in  the  external  malleolar  anastomosis,  along  with  the  external 
malleolar  of  the  anterior  tibial,  the  external  tarsal  of  the  dorsalis 
pedis,  and  the  posterior  peroneal. 


THE  LOWER  LIMB  499 

The  posterior  peroneal  artery  is  the  continuation  of  the  peroneal 
artery.  It  passes  behind  the  external  malleolus,  and  along  the 
outer  border  of  the  foot  for  a  variable  distance.  Its  branches 
are  chiefly  distributed  over  the  outer  surface  of  the  os  calcis, 
and  these  external  calcaneal  branches  take  part  in  the  external 
malleolar  anastomosis.  Over  the  prominence  of  the  heel  they 
anastomose  freely  with  the  internal  calcaneal  branches  of  the 
external  plantar,  and  on  the  outer  border  of  the  foot  the  pos- 
terior peroneal  again  anastomoses  with  branches  of  the  external 
plantar. 

The  peroneal  artery  is  accompanied  by  two  vena  comites,  which 
ultimately  join  the  posterior  tibial  venae  comites. 

Varieties  of  tlie  Posterior  Tibial  Artery.— The  vessel  is  sometimes  very  small 
m  which  cases  the  peroneal  artery  is  of  large  size,  as  well  as  the  communicating 
branch  normally  given  off  about  i  inch  above  the  ankle-joint,  and  so  the  small 
posterior  tibial  artery  is  reinforced.  In  rare  cases  the  vessel  does  not  reach 
the  ankle,  and  it  may  even  be  entirely  absent,  in  which  cases  there  is- always 
a  large  peroneal  artery  to  make  good  the  deficiency. 

Varieties  of  the  Peroneal  Artery.— The  level  at  which  this  vessel  arises  from 
the  posterior  tibial  is  subject  to  variety.  Its  normal  origin  is  fully  i  inch 
below  the  commencement  of  the  posterior  tibial,  but  it  may  arise  lower  down 
°^J^f^^^  ^P'  or  It  may  even  spring  from  the  popliteal,  or  from  the  anterior 
Ubial.  In  some  cases  it  is  of  large  size,  in  order  to  compensate  for  a  small 
posterior  tibial.  In  other  cases  the  peroneal  arterv  may  stop  short  of  the 
ankle,  its  place  being  taken  by  a  branch  of  the  poste'rior  tibial.  The  anterior 
peroneal  branch  is  sometimes  of  large  size,  in  order  that  it  may  reinforce 
a  small  anterior  tibial,  or  even  furnish  the  dorsalis  pedis  artery. 

Posterior  Tibial  Nerve.— This  nerve  is  the  continuation  of  the 
mternal  pophteal.  It  commences  at  the  lower  border  of  the 
popliteus  muscle,  and  its  normal  termination  corresponds  with  the 
lower  border  of  the  internal  annular  ligament,  where  it  divides  into 
internal  and  external  plantar  nerves.  The  division,  however, 
frequently  takes  place  at  the  upper  border  of  the  internal  annular 
ligament,  or  as  the  nerve  passes  beneath  it.  The  nerve  closely 
accompanies  the  posterior  tibial  artery  throughout  the  whole  of 
its  course.  It  lies  at  first  on  the  inner  side  of  the  artery,  with  the 
intervention  of  the  internal  vena  comes,  but  it  only  maintains  this 
position  for  about  i.\  inches.  It  then  crosses  over  the  vessel,  and 
descends  upon  its  outer  side,  the  external  vena  comes  intervening. 
The  general  relations  of  the  nerve  are  similar  to  those  of  the  corre- 
sponding artery. 

Branches.  —  These  are  muscular,  fibular,  calcaneo  -  plantar, 
articular,  and  terminal. 

The  muscular  branches  are  given  off  from  the  upper  part 
of  the  nerve,  and  supply  the  flexor  longus  digitorum,  tibialis 
posticus,  flexor  longus  hallucis,  and  soleus,  the  branch  to  the  last 
muscle  entering  it  on  its  deep  or  anterior  surface  near  the  centre 
of  the  leg. 

The  fibular  branch  is  a  long  nerve  which  is  usually  associated 
at  its  origin  with  the  branch  to  the  flexor  longus  hallucis.  It 
accompanies  the  peroneal  artery,  and   furnishes   (i)    a  medullary 

32—2 


Soo  A  MANUAL  OF  ANATOMY 

branch,  which  goes  with  the  medullary  artery  into  the  interior  of  the 
fibula  ;  (2)  periosteal  branches  to  the  fibular  periosteum ;  and  (3)  twigs 
to  the  coats  of  the  peroneal  artery. 

The  caleaneo-plantar  branch  arises  from  the  posterior  tibial 
whilst  it  is  beneath  the  internal  annular  ligament.  Having  pierced 
the  ligament,  it  divides  into  internal  calcaneal  and  plantar  branches. 
The  former  supply  the  integument  of  the  inner  side  of  the  heel, 
and  the  latter  are  the  cutaneous  nerves  of  the  inner  and  posterior 
part  of  the  sole. 

The  articular  branches,  two  or  three  in  number,  arise  from  the 
posterior  tibial  close  to  its  termination,  and  enter  the  ankle-joint  on 
its  inner  aspect  by  piercing  the  internal  lateral  ligament. 

The  terminal  branches  are  the  internal  plantar  and  external 
plantar  nerves,  which  will  be  afterwards  described. 


THE  KNEE-JOINT. 

The  knee-joint  belongs  to  the  class  diarthrosis,  and  to  the  sub- 
division ginglymus.  Though  the  chief  movements  are  flexion  and 
extension,  there  is  also  a  certain  amount  of  gliding  or  to  and  fro 
movement,  as  well  as  rotation.  The  joint,  therefore,  partakes  of 
the  nature  of  an  arthrodial  joint.  It  is  really  made  up  of  three 
joints,  namely,  one  into  which  the  patella  and  the  patellar  surface 
of  the  femur  enter  (femoro-patellar),  and  other  two  into  each  of 
which  a  femoral  condyle  and  a  tibial  condylar  surface  enter  (femoro- 
tibial).  These  three  joints  in  man  communicate  freely  with  one 
another. 

The  articular  surfaces  are  (i)  the  condyles  and  patellar  surface 
of  the  femur,  (2)  the  upper  three-fourths  of  the  posterior  surface 
of  the  patella,  and  (3)  the  condylar  articular  surfaces  of  the 
tibia. 

The  ligaments  are  divided  into  two  groups,  external  and 
internal. 

I.  External  Ligaments. — ^These  are  as  follows  :  anterior  or  liga- 
mentum  patellae,  posterior,  external  lateral,  internal  lateral,  and 
capsular. 

The  anterior  ligament  or  ligamentum  patellae  is  attached 
superiorly  to  the  apex  and  adjacent  margins  of  the  lower  part  of 
the  patella,  and  inferiorly  to  the  lower  rough  portion  of  the 
tubercle  of  the  tibia,  a  bursa  intervening  between  it  and  the 
upper  smooth  portion  of  the  tubercle.  It  is  a  very  strong,  flat, 
broad  ligament,  the  lateral  margins  of  which  are  connected  with 
the  lateral  patellar  ligaments. 

The  posterior  ligament  is  really  a  part  of  the  capsular 
ligament.  It  covers  the  back  parts  of  the  femoral  condyles,  and 
extends  between  the  external  and  internal  lateral  ligaments. 
Superiorly  it  is  attached  to  the  upper  margin  of  the  intercondylar 


THE  LOWER  LIMB  501 

fossa,  and  at  either  side  of  this  to  the  back  of  the  femur  immediately 
above  each  condyle.  Interiorly  it  is  attached  to  the  posterior 
border  of  the  head  of  the  tibia.  It  constitutes  a  broad  membranous 
ligament,  which  in  itself  is  thin,  but  it  receives  a  considerable 
accession  of  fibres  from  the  tendon  of  the  semimembranosus. 
These  fibres  form  a  strong  prominent  bundle,  which  represents  one 
mode  of  insertion  of  that  muscle,  and  is  known  as  the  ligamentum 


j_Ligamentum  Mucosum 
i.Post.  Crucial  Ligament 

!_  Ant.  Crucial  Ligament 


[_  Internal  .\lar  Ligament 


._Tendon  of  Quadriceps 
Extensor  Cruris 


Fig,  244. — Interior  of  the  Left  Knee-Joint 
(Anterior  View). 

posticum  Winslowii.  It  is  directed  upwards  and  outwards  from 
the  tendon  of  the  semimembranosus  towards  the  outer  condyle  of 
the  femur  and  outer  head  of  the  gastrocnemius.  Internally  the 
posterior  ligament  blends  with  the  internal  lateral  ligament,  and 
externally  (regarding  it  as  a  part  of  the  capsular  ligament)  it  sends 
an  expansion  over  the  long  external  lateral  ligament.  The  posterior 
ligament  presents  a  number  of  o])cnings  for  the  passage  of  nutrient 
vessels  and  nerves,  the  largest  of  these  being  at  its  centre  for  the 


S02 


A  MANUAL  OF  ANATOMY 


azygos  artery,  accompanied  by  a  branch  of  the  interna]  popHteal 
nerve  and,  it  may  be,  the  geniculate  branch  of  the  obturator  nerve. 
At  the  outer  part  of  the  hgament  there  is  a  special  opening  for  the 
tendon  of  the  popliteus.  Another  opening  is  frequently  present 
over  the  upper  and  back  part  of  the  inner  condyle,  and,  when 
this  is  so,  the  popliteal  bursa  between  the  semimembranosus  and 
the  inner  head  of  the  gastrocnemius  communicates  with  the 
synovial  membrane  of  the  joint.      The  upper  and  outer  part  of 


External  Head  of 
Gastrocnemius 


Long  Ext.  Lat.  Lig. — 

Short  Ext.  Lat.  Lig.    _ 
Popliteus 
Tendon  of  Biceps 


Tendon  of  Adductor 
Magnus 


Internal  Head  of 
Gastrocnemius 


Posterior  Ligament 

Ligamentum  Posti- 
cum  Winslowii 


Tendon  of  Semimem- 
branosus 


Expansion  to 
Popliteal  Fascia 


Popliteus  (cut) 

Fig.   245. — The  Left  Knee-Joint  (Posterior  View). 

the  posterior  ligament  gives  origin  to  some  of    the  fibres  of  the 
plantaris. 

The  external  lateral  ligament  consists  of  two  divisions — anterior 
and  posterior.  The  anterior  division  is  the  proper  external  lateral 
ligament,  and  is  known  as  the  long  external  lateral  ligament.  It  is 
firm  and  cord-like,  and  passes  vertically  downwards,  lying  clear  of 
the  joint.  It  is  attached  superiorly  to  the  external  tuberosity  of 
the  femur,  and  interiorly  to  the  outer  margin  of  the  head  of  the 
fibula  about  |  inch  anterior  to  the  styloid  process.  The  hgament 
crosses  the  tendon  of  the  popliteus,  and,  near  the  head  of  the  fibula, 


THE  LOWER  LIMB  503 

it  pierces  the  tendon  of  the  biceps  femoris,  being  there  provided  with 
a  synovial  investment.  The  inferior  external  articular  vessels  and 
nerve  pass  beneath  it.  The  long  external  lateral  ligament  repre- 
sents the  original  tendon  of  origin  of  the  peroneus  longus  from  the 
femur.  The  posterior  division  of  the  ligament,  which  is  known  as 
the  short  external  lateral  ligament,  lies  a  little  behind  the  long,  and  is 
not  well  defined.  If  distinct,  it  is  attached  above  to  the  external 
condyle  close  to  the  outer  head  of  the  gastrocnemius,  where  it  blends 
with  the  posterior  ligament,  its  inferior  attachment  being  to  the 
styloid  process  of  the  fibula.  Its  direction  is  downwards  and 
forwards,  and  it  is  to  be  regarded  as  an  expansion  in  that  direction 
of  the  posterior  ligament. 

The  internal  lateral  ligament  is  a  long,  flat,  strong  band  of 
unequal  width,  being  broader  at  the  centre  than  at  either  end. 
It  is  attached  superiorly  to  the  internal  tuberosity  of  the  femur, 
and  interiorly  to  the  internal  border  and  adjacent  part  of  the 
internal  surface  of  the  shaft  of  the  tibia,  extending  from  the 
internal  tuberosity  downwards  for  fully  3  inches.  Its  posterior 
border  covers  the  chief  part  of  the  tendon  of  the  semimembranosus, 
and  blends  with  the  posterior  ligament.  As  the  ligament  passes 
over  the  inner  side  of  the  knee-joint  it  is  closely  adherent  to  the 
internal  semilunar  fibro-cartilage,  and,  lower  down,  the  inferior 
articular  vessels  and  nerve  pass  beneath  it.  The  internal  lateral 
ligament  represents  the  original  insertion  of  the  adductor  magnus 
into  the  tibia. 

The  capsular  ligament  is  formed  to  a  large  extent  by  expansions 
derived  from  the  tendons  of  the  vastus  externus,  vastus  internus, 
sartorius,  and  semimembranosus,  and  from  the  fascia  lata.  It 
surrounds  the  joint  except  above  the  patella,  where  its  place  is 
taken  by  the  suprapatellar  tendon.  The  posterior  part  of  the 
capsule,  which  forms  the  posterior  ligament,  is  specially  strong, 
being  reinforced  by  the  ligamentum  posticum  Winslowii.  In  other 
situations  it  is  comparatively  thin.  It  furnishes  a  thin  expansion 
over  the  ligamentum  patellae,  and  on  either  side  of  the  patella  it 
forms  the  lateral  patellar  ligaments.  Externally,  where  it  is  closely 
incorporated  with  the  ilio-tibial  band  of  the  fascia  lata,  it  covers 
the  long  external  lateral  ligament.  Internally,  where  it  receives 
accessions  of  fibres  from  the  sartorius  and  semimembranosus,  it 
blends  with  the  internal  lateral  ligament. 

The  lateral  patellar  ligaments  are  two  in  number,  external 
and  internal,  and  they  take  the  form  of  flat  membranous  bands, 
sometimes  called  the  retinacula.  The  external  extends  between  the 
outer  border  of  the  patella  and  the  anterior  margin  of  the  outer 
tuberosity  of  the  tibia.  It  is  intimately  connected  with,  and  in 
part  formed  by,  the  ilio-tibial  band  of  the  fascia  lata.  The  internal 
extends  between  the  inner  border  of  the  patella  and  the  anterior 
margin  of  the  inner  tuberosity  of  the  tibia. 

2.  Internal  Ligaments. — The  interna  Hgaments,  i)roperly  so 
called,    are    as    follows  :    the    two     crucial    ligaments ;    the    two 


504 


A  MANUAL  OF  ANATOMY 


semilunar  fibro-cartilages,  with  their  coronary  hgaments ;  and 
the  transverse  ligament.  There  are  other  structures,  within  the 
joint,  designated  as  ligaments,  namely,  the  ligamentum  mucosum 
and  ligamenta  alaria  ;  but,  as  these  are  merely  folds  of  the  synovial 
membrane,  they  will  be  described  in  connection  with  it. 

Crucial  Ligaments.  —  These  are  two  in  number,  anterior  or 
external,  and  posterior  or  internal,  and  they  bind  the  condyles  of 
the  femur  to  the  head  of  the  tibia.  They  are  very  powerful, 
somewhat  round  bundles  situated  in  the  centre  of  the  joint,  and  so 
disposed  as  to  form  a  cross. 


Posterior  Crucial  Ligament  >/      ' 
Patellar  Facets 


Internal  Condyle f-Yh  . 


Internal  Semilunar 

Fibro-cartilage 


— Jjiv External  Condj'le 


Anterior  Crucial 

Ligamen  t 

External  Semilunar 

Fibro-cartilage 
Long  External  Lateral 
Ligament 

--.Transverse  Ligament 
Anterior  Superior 
Tibio-fibular  Ligament 


Fig.  246. — The  Crucial  Ligaments  of  the  Left  Knee-Joint 
(Anterior   View). 


The  anterior  or  external  crucial  ligament  is  attached  inferiorly  to 
the  inner  part  of  the  rough  depression  on  the  upper  surface  of  the 
head  of  the  tibia  in  front  of  the  inner  tubercle  of  the  spine. 
Superiorly  it  is  attached  to  the  depression  on  the  posterior  part 
of  the  internal  surface  of  the  external  condyle  of  the  femur.  Its 
direction  is  upwards,  backwards,  and  outwards.  At  its  tibial  attach- 
ment it  has  the  anterior  cornu  of  the  internal  semilunar  fibro-cartilage 
in  front  of  it,  and  the  anterior  cornu  of  the  external  semilunar  fibro- 
cartilage  behind  and  to  its  outer  side.  The  anterior  crucial 
ligament  is  tense  in  extension  of  the  knee-joint,  and  prevents  over- 
extension. It  is  also  tense  in  internal  rotation  of  the  leg.  The 
ligament  is  at  one  period  the  internal  lateral  ligament  of  the  external 
femoro-tibial  joint. 


THE  LOWER  LIMB 


505 


The  posterior  or  internal  crucial  ligament  is  attached  inferiorly 
to  the  back  part  of  the  rough  depression  on  the  head  of  the  tibia 
behind  the  spine,  and  to  the  pophteal  notch.  Superiorly  it  is 
attached  to  the  anterior  part  of  the  external  surface  of  the  internal 
condyle  of  the  femur,  close  to  the  front  part  of  the  intercondylar 
fossa,  upon  which  it  slightly  encroaches.  Its  direction  is  upwards, 
forwards,  and  slightly  inwards.  It  is  stronger,  but  shorter,  than 
the  anterior  crucial  ligament,  and  is  not  so  oblique.     At  its  tibial 


Anterior  Crucial - 
Ligament 


External  Semilunar_ 

Fibro-cartilage 
Synovial  Membrane- 
Long  External  Lateral. 
Ligament 
Posterior  Superior- 
Tibio-fibular 
Ligament 


-Internal  Semilunar 
1  ibro-cartilage 

.-  S\novial  Membrane 

Internal  Lateral 

I  igament 
Post.  Accessory  Bundle 

Posterior  Crucial 
Ligament 


Fig.  247. — The  Crucial  Ligaments  of  the  Left  Knee-Joint 
(Posterior  View)  (after  Spalteholz). 

attachment  it  is  behind  the  posterior  cornua  of  both  semilunar 
fibro-cartilages,  the  posterior  cornu  of  the  internal  one  being  more 
immediately  in  front  of  it  and  to  its  inner  side. 

The  posterior  crucial  ligament  is  tense  in  flexion  of  the  knee- 
joint,  and  checks  over-flexion.  It  is  at  one  period  the  external 
lateral  ligament  of  the  internal  femoro-tibial  joint. 

Two  views  may  be  stated  as  to  the  origin  of  the  crucial  Ugaments. 
(i)  According  to  Keith,  they  are  originally  parts  of  the  capsule  of  the  knee- 
joint,  but  have  become  separated  from  that  structure  as  the^  result  of  the 


5o6  A  MANUAL  OF  ANATOMY 

outgrowth  of  the  condyles  of  the  femur.  (2)  According  to  Bland-Sutton, 
they  are  modifications  of  muscles,  but  there  are  no  certain  facts  as  to  which 
muscles  they  originally  belonged. 

The  semilunar  fibro-cartilages  are  two  in  number — internal 
and  external.  They  are  lunated  plates,  of  very  firm  consist- 
ence, which  are  placed  upon  the  peripheral  parts  of  the  condylar 
articular  surfaces  of  the  tibia  so  as  to  deepen  them  for  the 
reception  of  the  condyles  of  the  femur.  They  also  serve  as 
cushions,  which  mitigate  pressure  and  diminish  shock.  Each 
presents  two  surfaces,  superior  and  inferior  ;  two  borders,  outer 
and  inner  ;  and  two  extremities  or  cornua,  anterior  and  posterior. 
The  superior  surface  is  slightly  concave  to  adapt  itself  to  a  femoral 
condyle,  being  sloped  from  the  outer  to  the  inner  border.  The 
inferior  surface  is  flat,  and  rests  upon  a  condylar  surface  of  the 
tibia  at  its  circumference.  Both  these  surfaces  are  covered  by  the 
synovial  membrane  of  the  joint.  The  outer  border  is  convex  and 
thick,  and  it  is  attached  to  the  margin  of  the  corresponding  tuber- 
osity of  the  tibia  by  fibres  which  are  really  a  part  of  the  capsular 
ligament,  but  which  have  received  the  name  of  coronary  ligament 
(one  for  each  fibro-cartilage).  The  external  semilunar  fibro- 
cartilage  is  more  loosely  attached  in  this  manner  than  the  internal. 
Partly  on  this  account,  and  partly  by  reason  of  the  close  proximity 
of  its  two  comua,  the  external  fibro-cartilage  is  more  movable  than 
the  internal.  The  inner  border  of  each  fibro-cartilage  is  very  thin, 
sharp,  and  concave.  It  is  quite  free,  and  covered  by  the  synovial 
membrane. 

The  extremities  or  cornua  are  thin  fibrous  bands,  which  have 
the  following  attachments :  the  anterior  cornu  of  the  internal 
semilunar  fibro-cartilage  is  attached  to  the  rough  depression  in 
front  of  the  spine  of  the  tibia  at  its  anterior  and  inner  part  ;  or,  to 
put  it  in  another  way,  it  is  attached  to  the  upper  surface  of  the 
head  of  the  tibia  in  front,  and  to  the  outer  side,  of  the  internal 
condylar  surface.  It  has  the  anterior  crucial  ligament  directly 
behind  it.  The  posterior  cornu  is  attached  to  the  inner  part  of  the 
rough  depression  behind  the  spine  of  the  tibia,  where  it  has  the 
posterior  crucial  ligament  behind  it.  The  internal  semilunar  fibro- 
cartilage  is  semicircular,  and  may  be  likened  to  the  capital  letter  C, 
its  cornua  being  wide  apart,  and  embracing  between  them  the 
cornua  of  the  external  semilunar  fibro-cartilage.  It  is  intimately 
connected  with  the  internal  lateral  ligament. 

The  anterior  cornu  of  the  external  semilunar  fibro-cartilage  is 
attached  to  the  head  of  the  tibia  immediately  in  front  of  the  outer 
tubercle  of  the  spine,  where  it  is  placed  on  the  outer  side  of  and 
behind  the  anterior  crucial  ligament.  The  posterior  cornu  is 
attached  to  the  rough  depression  between  the  two  tubercles  of  the 
spine,  and  also  to  a  depression  immediately  behind  the  outer 
tubercle.  The  external  semilunar  fibro-cartilage  is  almost  circular, 
thus  O,  its  cornua  being  very  close  together,  and  being  embraced 
by  the  cornua  of  the  internal  semilunar  fibro-cartilage.     The  pos- 


THE  LOWER  LIMB 


507 


terior  and  outer  aspect  of  the  external  semilunar  fibro-cartilage  is 
grooved  by  the  tendon  of  the  popliteus,  and  this  tendon  separates 
it  from  the  long  external  lateral  ligament,  whilst  posteriorly  it  is 
connected  with  the  posterior  ligament. 

The  semilunar  fibro-cartilages  move  forwards  when  the  knee- 
joint  is  extended,  and  backwards  when  it  is  flexed,  the  external 
more  so  than  the  internal. 

The  so-called  coronary  ligaments  are  really  portions  of  the 
capsular  ligament.  They  represent  fibres  which  connect  the  outer 
convex  borders  of  the  semilunar  iibro-cartilages  to  the  margins  of 
the  tuberosities  of  the  tibia,  more  loosely  in  the  case  of  the  external 
than  the  internal. 


Anterior  Crucial  Ligament 

Ant.  Cornu  of  Internal 
Semilunar  Fibro-cartilage 


Transverse  Ligament 


Int.  Semilunar 
Fibro-cartilage 


Ant.  Cornu  of  External 
Semilunar  Fibro-cartilage 


-Fxt    Semilunar 
I*  ibro-cartilage 


Post.  Cornu  of  Internal  Semilunar 
Fibro-cartilage 


Post   Cornu  of  External  Semilunar 
Fibro-cartilage 


Posterior  Crucial 
Ligament 


Fig.   248. — The  Ligaments  and  Fibro-C.\rtilage.s  on  the   Head  of  the 

Right  Tibia. 


In  connection  with  the  external  semilunar  libro-cartilage  there  are  two 
accessory  bundles,  anterior  and  posterior.  The  posterior  bundle  extends  from 
the  back  part  of  the  external  semilunar  fibro-cartilage  to  the  external  surface 
of  the  internal  condyle  of  the  femur,  where  it  is  attached  close  to  the  posterior 
crucial  ligament.  It  is  thick  and  strong,  and  may  be  double,  in  which 
case  the  two  Vjundles  are  disposed  one  in  front  of,  and  the  otlier  behind,  the 
posterior  crucial  ligament.  If  single  it  may  be  in  front  of  that  ligament,  or 
behind  it,  and  it  may  he  closely  connected  with  tlie  tibial  attachment  of  the 
ligament.  It  serves  as  a  kind  of  anchor  to  the  back  ])art  of  the  external 
semilunar  fibro-cartilage,  and  so  prevents  too  much  displacement  of  it  during 
rotation.     The  anterior  bundle  constitutes  the  transverse  ligament. 

The  external  semilunar  fibro-cartilage  is  to  be  regarded  as  originating  from 
the  biceps  femoris,  and  the  internal  from  the  semimembranosus,  certain  tex- 
tural  alterations  having  taken  place  in  the  course  of  the  metamorjihosis. 

The  transverse  ligament  is  a  narrow  band  which  extends 
from   the   front   of   the   external   semilunar  fibro-cartilage   to   the 


5o8 


A  MANUAL  OF  ANATOMY 


front  of  the  internal.  It  prevents  the  front  part  of  the  external 
semilunar  fibro-cartilage  from  moving  too  far  backwards  during 
flexion  of  the  joint. 

The  synovial  membrane  invests  the  inner  surface  of  the  capsular 
ligament.  On  reaching  the  semilunar  fibro-cartilages  it  is  reflected 
over  their  upper  and  under  surfaces,  and  is  then  conducted  by  the 
coronary  hgaments  to  the  margins  of  the  tuberosities  of  the  tibia. 
Between  the  front  of  the  head  of  the  tibia  and  the  patella  the 
membrane  covers  a  collection  of  fat,  known  as  the   infrapatellar 


Suprapatellar  Bursa 

-  Quadriceps  Extensor  Cruris 


Pouch  of  Synovial 
Membrane  of  Knee-joint 


Popliteus 

Lateral  Ligament.. 


Semilunar  Fibro-cartilage 
Liffamentum  Patellas 


Bursa  beneath  Ligamentum 
Patella 


Fig.  249. — The  Synovial  Membrane  of  the  Right  Knee-Joint 
(External  View)  (after  Spalteholz). 

pad,  and  in  this  situation  it  is  raised  into  certain  folds,  called 
ligaments,  namely,  the  ligamentum  mucosum  and  ligamenta  alaria, 
to  be  presently  described.  Above  the  patella  the  membrane 
extends  upwards  in  the  form  of  a  large  pouch  upon  the  front  of  the 
shaft  of  the  femur  for  about  2  inches  above  the  upper  border  of 
the  patellar  surface  of  the  bone.  This  pouch  Hes  beneath 
the  suprapatellar  tendon  of  the  quadriceps  extensor  cruris,  and 
communicates  with  the  suprapatellar  bursa,  which  is  situated 
immediately  above  it,  and  which  extends  upwards  for  about  i  inch 
beneath  the  suprapatellar  tendon. 


THE  LOWER  LIMB  509 

From  the  posterior  ligament  the  synovial  membrane  is  reflected 
forwards  in  the  form  of  two  laminae,  one  of  which  passes  over  the 
outer  surface  of  the  anterior  crucial  ligament,  and  the  other  over 
the  inner  surface  of  the  posterior  crucial  ligament.  After  having 
done  so,  these  two  laminae  become  continuous  with  each  other  in 
front  of  the  crucial  ligaments.  It  will  thus  be  evident  that  the 
following  parts  of  these  ligaments  are  destitute  of  synovial 
membrane  :  (i)  the  posterior  surface  of  each  ligament,  and  (2) 
that  part  of  the  anterior  surface  of  the  posterior  ligament  which  is 
in  contact  with  the  anterior  ligament. 

In  connection  with  the  posterior  ligament  of  the  knee-joint  it 
is  to  be  noted  that  there  is  a  narrow  median  vertical  zone  which 
is  destitute  of  synovial  membrane,  on  account  of  the  forward  reflec- 
tion of  that  membrane  in  two  laminae.  This  interlaminar  zone  is 
covered  by  a  certain  amount  of  fat. 

The  synovial  membrane  furnishes  an  investment  to  the  tendon 
of  the  popliteus,  which  separates  that  tendon  from  the  long  external 
lateral  ligament.  This  prolongation  also  extends  in  a  downward 
direction  between  the  posterior  part  of  the  external  semilunar 
fibro-cartilage  and  the  outer  tuberosity  of  the  tibia,  so  as  to  facilitate 
the  movement  of  the  tendon  of  the  popliteus  at  that  point.  It 
may  extend  so  far  down  as  to  become  continuous  with  the  synovial 
membrane  of  the  superior  tibio-fibular  joint.  At  the  back  of  the 
joint  the  synovial  membrane  frequently  communicates  with  the 
popliteal  bursa  between  the  semimembranosus  and  inner  head  of 
the  gastrocnemius. 

The  synovial  membrane,  as  it  covers  the  infrapatellar  pad  of 
fat,  forms  three  folds — the  ligamentum  mucosum  and  ligamenta 
alaria.  The  ligamentum  mucosum,  which  contains  a  little  fat, 
extends  backwards  to  be  attached  to  the  front  part  of  the  inter- 
condylar fossa  of  the  femur.  It  is  narrow  and  pointed  at  its 
femoral  attachment,  but  over  the  infrapatellar  pad  of  fat  it 
widens  out  and  becomes  triangular.  The  lateral  borders  of  this 
latter  part  of  the  ligamentum  mucosum  constitute  the  so-called 
ligamenta  alaria,  which  extend  for  a  short  distance  in  an  upward 
direction  along  the  lateral  margins  of  the  patella. 

The  ligamentum  mucosum,  which  serves  to  adjust  the  infra- 
patellar pad  of  fat  to  the  different  positions  of  the  joint,  is  the 
remains  of  the  double  synovial  partition  which  originally  separates 
the  femoro-tibial  articulations. 

The  articular  fat  forms  two  chief  collections,  called  infrapatellar 
and  suprapatellar,  which  represent  the  Haversian  glands  of  the 
knee-joint.  The  infrapatellar  pad  is  the  larger  of  the  two,  and 
fills  up  the  sj)ace  between  the  lower  end  of  the  femur,  the  head  of 
the  tibia,  and  the  patella  with  its  ligament.  It  adapts  itself  to  the 
different  positions  of  the  joint,  and  the  ligamentum  mucosum  acts 
as  its  regulator.  The  suprapatellar  pad  is  situated  around  the 
suprapatellar  bursa  and  the  j)ouch  which  the  synovial  membrane 
sends  upwards  above  the  patellar  surface  of  the  femur. 


Sio 


A  MANUAL  OF  ANATOMY 


Muscular  Relations. — ^The  muscular  relations  are  as  follows  : 

Anterior. — The  quadriceps  extensor  cruris. 

External. — ^The  biceps  femoris. 

Posterior. — The  popliteus,  plantaris,  and  outer  head  of  the 
gastrocnemius  externally,  and  the  inner  head  of  the  gastrocnemius 
and  semimembranosus  internally. 

Internal. — ^The  sartorius,  gracilis,  semitendinosus,  and  semi- 
membranosus. 

Arterial  Supply. — The  joint  receives  its  arterial  supply  from  the 
following  sources  :  (i)  the  long  descending  branch  of  the  external 
circumflex  of  the  arteria  profunda  femoris  ;  (2)  the  deep  branch  of 


Subcrureus 

— Suprapatellar  Bursa 


Posterior  Ligament. 
Posterior  Crucial  Ligament. 

Anterior  Crucial  Ligament 


Pouch  of  Synovial  Membrane 
of  Knee-joint 

—  Prepatellar  Bursa 


-Ligamentum  PatelltE 
-Ligamentum  Mucosum 

-Infrapatellar  Pad  of  Fat 

Bursa  beneath 
_]jigamentum  Patellae 


.-Skin 


Fig.  250. — Sagittal  Section  of  the  Right  Knee-Joint,  viewed 
FROM  the  Outer  Side. 


the  anastomotica  magna  of  the  superficial  femoral  ;  (3)  the  superior 
and  inferior  external  and  internal  articular  and  the  central  or 
azygos  articular  branches  of  the  popliteal ;  and  (4)  the  anterior 
tibial  recurrent  and  posterior  tibial  recurrent  (inconstant)  branches 
of  the  anterior  tibial. 

Nerve-supply. — ^The  joint  receives  its  nerves  from  the  following 
sources  :  (i)  the  external  and  internal  popliteal,  both  from  the 
great  sciatic  ;  (2)  the  anterior  crural  ;  and  (3)  the  obturator. 

The  external  popliteal  nerve  furnishes  three  articular  branches, 
one  with  the  superior  external  articular  artery,  one  with  the  inferior 
external  articular,  and  a  recurrent  branch  with  the  anterior  tibial 
recurrent.     The  internal  popliteal  nerve  furnishes  three  (sometimes 


THE  LOWER  LIMB 


S" 


Superior 
Internal  Articular 


Superior 
External  Articular 


two)  articular  branches,  one  with  the  superior  internal  articular 
arterj^  (inconstant),  one  with  the  central  or  azygos  articular,  and 
one  with  the  .inferior  internal  articular. 

The  anterior  crural  nerve  furnishes  articular  branches  as  follows  : 
(I)  the  nerve  to  the  vastus  externus  furnishes  one  articular 
branch  ;  (2)  the  most  internal  of  the  branches  to  the  crureus 
furnishes  another  articular  branch,  which  in  its  course  supplies 
the  subcrureus  ;  and  (3)  the  nerve  to  the  vastus  internus  furnishes 
a  third  articular 
branch,    which    is    .     ,       .    ^,  (! 

'  .  Anastomotica  Magna  — | 

of      large       size,       and  (Deep  Branch) 

ultimately  accom- 
panies the  deep 
branch  of  the 
anastomotica  magna 
artery. 

The  obturator 
nerve,  by  its  deep 
or  posterior  division, 
furnishes  an  articular 
branch  called  the 
geniculate  nerve. 
This  branch,  how- 
ever, may  be  absent. 

If  the  nerve-supply 
of  the  knee-joint  is 
compared  with  that 
of  the  hip-joint,  it 
will  be  evident  that 
there  is  a  nervous 
sympathy  between 
these  two  articula- 
tions. 

Movements — Femoro- 
tibial  Joint  s. — T  h  e 
movements  between  the 
condyles  of  the  femur 
and  the  condylar  ar- 
ticular surfaces  of  the 
tibia  are  of  two  kinds, 
namely,  flexion  and  ex- 
tension, and  rotation,  the  latter  movement  being  only  possible  when  the 
knee-joint  is  flexed. 

Flexion  and  Extension. — These  movements  are  complicated  by  the  spiral 
outline  of  the  femoral  condyles,  and  they  partake  partly  of  gliding  and  partly 
of  rolling.  During  extension  the  two  condyles  move  parallel  to  each  other 
up  to  a  certain  stage,  namely,  towards  the  end  of  extension.  When  this 
stage  has  been  reached,  the  anterior  part  of  the  outer  condyle  is  in  contact 
with  the  outer  tibial  articular  surface.  The  inner  condyle,  however,  being 
longer  than  the  outer,  continues  to  glide  backwards  so  as  to  bring  its  oblicjue 
anterior  part  into  contact  with  the  inner  tibial  articular  surface.  The  result 
is  that  the  femur  is  rotated  inwards  on   the  tibia.      Hence,  at  the  very  corn- 


Inferior  Int 
.Vrticular 


Fig.  251. — The  Deep  Anastomo.ses  round  the 
Knee-Joint  (Anterior  View)  (Tiedemann). 


512  A  MANUAL  OF  ANATOMY 

mencement  of  flexion,  the  femur  is  rotated  outwards  on  the  tibia.  When 
the  joint  is  completely  extended,  the  following  ligaments  are  rendered  tense  : 
(i)  anterior  crucial,  (2)  posterior  ligament,  and  (3)  long  external  lateral  and 
internal  lateral  ligaments.  Over-extension  is  checked  (i)by  the  tightening 
of  the  anterior  crucial,  the  posterior  ligament,  and  the  two  lateral  ligaments  ; 
(2)  by  the  anterior  portions  of  the  semilunar  fibro-cartilages  being  pressed 
into  the  depressions  of  the  femoral  condyles  ;  (3)  by  the  locking  which  takes 
place  between  the  anterior  crucial  ligament  and  the  front  part  of  the  inter- 
condylar fossa  ;  and  (4)  by  the  locking  which  takes  place  between  the  inner 
depression  of  the  outer  femoral  condyle  and  the  front  of  the  outer  tubercle 
of  the  tibial  spine  (Bruce  Young).  At  the  end  of  extension  the  outer  con- 
dyle pushes  the  anterior  and  inner  part  of  the  external  semilunar  fibro-cartilage 
over  the  anterior  and  inner  border  of  the  outer  condylar  surface  of  the 
tibia.  When  this  has  been  done,  the  depression  at  the  inner  end  of  the 
groove  on  the  outer  condyle  comes  into  contact  with  the  front  of  the  outer 
tubercle  of  the  tibial  spine,  and  with  a  special  facet  in  front  of  that  tubercle 
(at  the  anterior  and  inner  part  of  the  outer  condylar  surface  of  the  tibia), 
and  so  the  locking  takes  place. 

In  flexion  of  the  knee-joint  the  external  ligaments  are  relaxed,  except 
the  ligamentum  patellae.  Over-flexion  is  checked  by  (i)  the  stretching  of 
the  quadriceps  extensor  cruris  ;  (2)  the  meeting  of  the  fleshy  parts  of  the 
calf  and  back  of  the  thigh  ;  (3)  the  tightening  of  the  posterior  crucial 
ligament  ;  and  (4)  the  extreme  posterior  and  outer  part  of  the  inner  condyle 
(which  here  presents  a  special  facet)  being  pressed  against  the  back  part 
of  the  inner  tubercle  of  the  tibial  spine  (Cleland). 

In  extension  of  the  joint  the  semilunar  fibro-cartilages  move  forwards, 
and  in  flexion  they  move  backwards. 

Rotation. — This  movement  is  impossible  in  extension  of  the  knee-joint, 
owing  to  the  tightening  of  the  anterior  crucial  and  the  external  ligaments,  except 
the  ligamentum  patellse.  In  semiflexion,  however,  a  fair  amount  of  rotation 
is  allowed.  Internal  rotation  is  checked  by  the  anterior  crucial  ligament, 
and  external  rotation  by  the  internal  lateral  ligament. 

The  range  of  rotation  is  about  40  degrees.  Assuming  that  all  the  muscles 
and  external  ligaments  are  cut,  in  which  case  the  femur  and  tibia  would  be 
connected  only  by  the  crucial  ligaments,  if  the  femur  is  grasped  firmly  and 
the  tibia  rotated  inwards  the  movement  will  be  seen  to  be  arrested  by  the 
tightening  of  the  anterior  crucial  ligament.  If,  however,  the  tibia  is  rotated 
outwards  neither  crucial  ligament  interferes  with  the  movement,  so  that  the 
tibia  can  be  made  to  describe  half  a  circle,  thus  directing  the  front  of  the 
head  of  the  bone  backwards. 

Muscles  concerned  in  the  Movements — Flexion. — The  muscles  which  pro- 
duce flexion  are  the  biceps  femoris,  semitendinosus,  semimembranosus,  sar- 
torius,  gracilis,  and  popliteus.  If  the  ankle-joint  is  fixed,  the  gastrocnemius, 
with  the  plantaris  as  a  feeble  auxiliary,  acts  as  a  flexor.  Extension. — 
The  chief  extensor  is  the  quadriceps  extensor  cruris.  The  gluteus  maximus 
and  tensor  fasciae  femoris,  however,  take  part  in  the  completion  of  extension 
by  means  of  the  iUo-tibial  band  of  the  fascia  lata.  Internal  Rotation. — This 
movement  is  produced  by  the  popliteus,  semitendinosus,  semimembranosus, 
gracihs,  and  sartorius,  in  each  case  after  flexion  has  been  effected.  External 
Rotation. — This  movement  is  produced  by  the  biceps  femoris  after  it  has 
flexed  the  joint. 

Femoro  -  patellar  Joint.  —  The  movement  at  this  joint  is  of  a  gliding 
or  to-and-fro  nature,  associated  with  a  certain  amount  of  rolling  of  the  patella, 
the  result  of  which  is  to  bring  different  parts  of  the  opposed  articular  surfaces 
into  contact  in  different  positions  of  the  joint.  This  combination  of  gliding 
and  rolling  constitutes  the  movement  called  coaptation.  In  extension  of  the 
knee,  when  the  patella  is  drawn  up  by  the  quadriceps  extensor  cruris,  the 
inferior  pair  of  patellar  facets  are  in  contact  with  the  upper  part  of  the  patellar 
surface  of  the  femur.  In  semiflexion  the  middle  pair  of  patellar  facets  are 
in  contact  with  the  middle  part  of  the  patellar  surface  of  the  femur.  In 
■ordinary  flexion  the  upper  pair  of  patellar  facets  are  in  contact  with  the 


THE  LOWER  LIMB  513 

lower  part  of  the  patellar  surface  of  the  femur.  In  extreme  flexion,  as  in  the 
position  assumed  by  the  miner  when  at  work,  the  patella  is  entirely  off  the 
patellar  surface  of  the  femur,  and,  being  turned  outwards  by  the  internal 
condyle,  the  inner  vertical  facet  of  the  patella  articulates  with  the  semilunar 
facet  on  the  outer  part  of  thetibial  surface  of  the  internal  condyle  close  to  the 
intercondylar  fossa,  and  the  upper  and  outer  horizontal  patellar  facet  is  in 
contact  with  the  front  part  of  the  external  condyle  of  the  femur.  When  the 
patella  is  turned  inwards  in  extension  of  the  joint,  the  outer  lateral  patellar 
ligament  is  put  upon  the  stretch,  and  so  prevents  over-displacement  inwards. 
When  the  patella  is  turned  outwards  in  flexion  by  the  internal  condyle,  the 
inner  lateral  patellar  ligament  is  put  upon  the  stretch,  and  so  prevents  over- 
displacement  outwards. 

When  a  person  stands  erect  with  both  feet  upon  the  ground,  the  vertical 
line  of  the  centre  of  gravity  falls  in  front  of  the  axis  of  movement  at  the 
knee-joint.  There  is  thus  a  tendenc^^  to  over-extension,  which,  however,  is 
resisted  by  the  tension  of  the  Ugaments.  In  the  erect  attitude  the  knee-joint 
is,  therefore,  maintained  in  a  state  of  extension  to  a  large  extent  without 
muscular  effort.  This  is  proved  by  the  fact  that  each  patella  is  freely 
movable.  When,  however,  one  hmb  is  raised  from  the  ground,  muscular 
effort  now  becomes  necessary  to  maintain  extension,  and  the  patella  of 
each  limb  becomes  fixed.  The  gluteus  maximus  and  tensor  fasciae  femoris 
muscles,  acting  through  the  iho-tibial  band  of  the  fascia  lata,  contribute  to 
the  maintenance  of  extension  at  the  knee-joint,  as  in  standing. 


SOLE  OF  THE  FOOT. 

Landmarks. — Along  the  inner  border  of  the  foot  there  are  several 
important  bony  landmarks  which  can  be  made  out  without  much 
difficulty.  The  internal  malleolus  is  a  good  starting-point.  One 
inch  below  this  projection  the  sustentaculum  tali  of  the  os  calcis 
can  be  felt,  and  a  little  in  front  of  it  is  the  tuberosity  of  the  navicular 
or  scaphoid  bone.  The  navicular  tuberosity  is  situated  about 
i^  inches  in  front  of  the  internal  malleolus,  and  on  a  lower  level. 
The  recess  between  the  sustentaculum  tali  and  the  navicular 
tuberosity  is  bridged  over  by  the  spring  ligament  and  the  tendon 
of  the  tibialis  posticus,  the  latter  being  the  more  superficial. 
Immediately  in  front  of  the  navicular  tuberosity  the  eminence 
on  the  plantar  surface  of  the  internal  cuneiform  bone  may  be  felt. 
and  anterior  to  it  is  the  tuberosity  on  the  plantar  aspect  of  the 
proximal  end  of  the  first  metatarsal  bone.  Along  the  outer  border 
two  projections  can  be  felt,  namely,  the  external  malleolus  and 
the  tuberosity  on  the  outer  side  of  the  proximal  end  of  the  fifth 
metatarsal  bone. 

The  guide  to  the  astragalo-navicular  joint  on  the  inner  side  of 
the  foot  is  the  tuberosity  of  the  navicular  bone,  the  joint  being 
situated  immediately  behind  that  tuberosity.  The  guide  to  the 
calcaneo-cuboid  joint  on  the  outer  side  of  the  foot  is  a  point  midway 
between  the  external  malleolus  and  the  tuberosity  on  the  outer  side 
of  the  proximal  end  of  the  fifth  metatarsal  bone.  The  astragalo- 
navicular  and  calcaneo-cuboid  joints  lie  in  the  same  transverse 
plane,  and  are  the  joints  at  which  disarticulation  is  performed  in 
Chopart's  operation.     The  guide  to  the  joint  between  the  internal 

33 


514  A  MANUAL  OF  ANATOMY 

cuneiform  and  first  metatarsal  bones  is  a  point  i^  inches  in  front  of 
the  navicular  tuberosity.  This  is  to  be  remembered  in  connection 
with  the  tarso-metatarsal  operations  of  Lisfranc  and  Hey.  The 
joint  between  the  cuboid  and  fifth  metatarsal  bones  is  situated 
immediately  behind  the  tuberosity  on  the  outer  side  of  the  proximal 
end  of  the  fifth  metatarsal  bone. 

The  course  of  the  external  plantar  artery  is  complicated  by  the 
fact  that  it  first  crosses  the  sole  of  the  foot  from  within  outwards, 
and  afterwards  from  without  inwards.  The  former  course  is 
indicated  by  a  line  drawn  from  a  point  midway  between  the  inner 
part  of  the  point  of  the  heel  and  the  tip  of  the  internal  malleolus 
to  a  point  about  i  inch  internal  to  the  tuberosity  on  the  outer  side 
of  the  base  of  the  fifth  metatarsal  bone.  A  line  drawn  from  the 
latter  point  to  the  proximal  part  of  the  first  interosseous  space 
indicates  the  position  of  the  artery  as  it  recrosses  the  foot.  To 
indicate  the  course  of  the  internal  plantar  artery  start  from  the 
same  point  as  for  the  commencement  of  the  external  plantar  vessel, 
and  draw  a  line  to  the  centre  of  the  metatarso-phalangeal  joint  of 
the  great  toe. 

The  skin  of  the  sole  is  characterized  by  great  thickness  over 
the  bony  prominences  of  the  heel  and  balls  of  the  toes,  in  which 
situations  bursge  are  frequently  developed.  The  superficial  fascia 
is  coarse  and  granular.  It  forms  a  thick  pad  composed  of  lobules 
of  fat,  which  lie  between,  and  are  supported  by,  processes  of  fibrous 
tissue  passing  between  the  skin  and  the  plantar  fascia. 

Plantar  Fascia  or  Aponeurosis. — The  plantar  fascia  is  connected 
to  the  skin  by  fibrous  processes,  which  enclose  and  support  the 
lobules  of  the  superficial  fascia,  and  it  presents  two  longitudinal 
grooves,  along  the  course  of  which  intermuscular  septa  pass  deeply 
into  the  sole.  These  grooves  indicate  the  division  of  the  plantar 
fascia  into  three  portions — central  and  two  lateral. 

The  central  division  covers  the  flexor  brevis  digitorum,  and  is  of 
considerable  strength.  It  is  triangular,  being  somewhat  pointed 
behind  and  expanded  in  front.  Posteriorly,  where  it  is  narrow 
and  thick,  it  is  attached  to  the  inner  tubercle  on  the  plantar  aspect 
of  the  tuber  calcis.  From  this  point  the  fibres  pass  forwards 
towards  the  toes,  the  central  division  meanwhile  widening  out  and 
becoming  thinner.  At  the  heads  of  the  metatarsal  bones  it  divides 
into  five  digital  processes,  one  for  each  toe.  The  direction  of  its 
fibres  is  longitudinal — that  is  to  say,  they  run  from  heel  to  toes, 
but  towards  the  balls  of  the  toes  transverse  fibres  make  their 
appearance.  Moreover,  in  the  webs  of  the  toes  there  are  other 
superadded  transverse  fibres,  which  constitute  the  superficial 
transverse  ligament.  This  ligament  arches  over  the  digital  vessels, 
nerves,  lumbricales  muscles,  and  digital  processes.  Each  of  the 
five  digital  processes  forms  an  arch  over  the  flexor  tendons  as 
these  are  about  to  pass  to  the  plantar  aspects  of  the  toes.  The 
final  disposition  of  each  process  is  as  follows  :  (i)  it  is  attached 
■superficially  to  the  skin  ;  (2)  it  joins  the  vaginal  ligament  of  the 


THE  LOWER  LIMB 


51S 


Abductor  Hallucis 


Flexor  Longus  Hallucis 


Flexor  Brevis  Hallucis_ 


_  Flexor  Brevis 

Digitorum 
.Abductor  Minimi 
Digiti 

.  Flexor  Brevis 
JNIinimi  Digiti 


s^Lumbricales 


Fig.  252. — The  Plantar  Fascia,  and  First  Layer  of  Muscles  (in  part). 


33—2 


5i6  A  MANUAL  OF  ANATOMY 

flexor  sheath  anteriorly  ;  and  (3)  at  each  side  of  the  flexor  tendons 
it  sends  a  deep  process  upwards,  which  joins  the  transverse  meta- 
tarsal (deep  transverse)  ligament  connecting  the  heads  of  the 
metatarsal  bones,  and  is  also  attached  to  the  corresponding 
lateral  metatarso-phalangeal  ligament.  There  is  thus  formed  a 
tunnel  for  the  passage  of  the  flexor  tendons.  The  lumbricales 
muscles  and  the  digital  vessels  and  nerves  make  their  appearance 
between  the  diverging  digital  processes.  The  central  division 
contributes  to  the  maintenance  of  the  longitudinal  arch  of  the 
foot  by  its  tendency  to  approximate  the  toes  to  the  heel.  When  it 
becomes  contracted  it  gives  rise  to  an  exaggeration  of  the  longi- 
tudinal arch,  a  condition  known  as  pes  cavus.  Morphologically 
it  represents  the  divorced  plantar  portion  of  the  tendon  of  the 
plantaris. 

The  external  division  is  weaker  than  the  central.  It  is  attached 
posteriorly  to  the  outer  tubercle  on  the  plantar  aspect  of  the 
tuber  calcis,  whence  it  passes  forwards  over  the  abductor  minimi 
digiti  muscle.  Internally  it  is  continuous  with  the  central  division 
along  the  line  of  attachment  of  the  external  intermuscular  septum  ; 
externally  it  is  continuous  round  the  outer  border  of  the  foot 
with  the  deep  fascia  of  the  dorsum  ;  and  anteriorly,  having  become 
very  thin,  it  is  attached  to  the  proximal  end  of  the  first  phalanx  of 
the  little  toe  on  its  outer  aspect.  This  division  forms  a  specially 
strong  band  between  the  outer  tubercle  of  the  os  calcis  and  the 
tuberosity  on  the  outer  side  of  the  base  of  the  fifth  metatarsal 
bone,  which  is  the  remains  of  the  abductor  ossis  metatarsi  quinti,  or 
Wood's  muscle. 

The  internal  division  is  the  weakest  of  the  three.  It  is 
attached  posteriorly  to  the  internal  aspect  of  the  inner  tubercle 
on  the  plantar  surface  of  the  tuber  calcis,  and  to  the  lower  border 
of  the  internal  annular  ligament,  whence  it  passes  forwards  over 
the  abductor  hallucis  muscle.  Externally  it  is  continuous  with 
the  central  division  along  the  line  of  attachment  of  the  internal 
intermuscular  septum  ;  internally  it  is  continuous  round  the  inner 
border  of  the  foot  with  the  deep  fascia  of  the  dorsum  ;  and 
anteriorly,  where  it  becomes  very  thin,  it  is  attached  to  the 
proximal  end  of  the  first  phalanx  of  the  great  toe  on  its  inner 
aspect. 

The  intermuscular  septa  are  two  in  number,  external  and  internal, 
and  they  extend  upwards  into  the  sole  at  either  side  of  the  central 
division  along  the  course  of  the  longitudinal  grooves.  They  are 
situated  on  either  side  of  the  flexor  brevis  digitorum,  the  internal 
septum  lying  between  that  muscle  and  the  abductor  hallucis, 
and  the  external  septum  intervening  between  it  and  the  abductor 
minimi  digiti.  Each  septum  gives  partial  origin  to  the  muscles 
between  which  it  lies.  The  plantar  fascia  and  the  two  inter- 
muscular septa  form  three  muscular  compartments — inner,  middle, 
and  outer. 

Cutaneous   Nerves.  —  The   cutaneous    nerves    are    as    follows  : 


THE  LOWER  LIMB  517 

calcaneo-plantar,  branches  of  the  internal  plantar,  and  branches 
of  the  external  plantar. 

The  calcaneo-plantar  nerve  is  a  branch  of  the  posterior  tibial 
whilst  that  nerve  is  beneath  the  internal  annular  lig;ament. 
Having  pierced  that  ligament,  the  nerve  divides  into  internal 
calcaneal  and  plantar  branches.  The  former  supplies  the  integu- 
ment of  the  inner  side  of  the  heel,  and  the  latter  the  inner  and 
posterior  part  of  the  sole. 

The  plantar  cutaneous  branches  of  the  internal  plantar  nerve 
appear  along  the  groove  between  the  abductor  hallucis  and  flexor 
brevis  digitorum,  and,  having  pierced  the  plantar  fascia,  are 
distributed  to  the  integument  of  the  inner  half  of  the  sole. 

The  plantar  cutaneous  branches  of  the  external  plantar  nerve 
appear  along  the  groove  between  the  iiexor  brevis  digitorum  and 
abductor  minimi  digiti,  and,  having  pierced  the  plantar  fascia, 
are  distributed  to  the  integument  of  the  outer  half  of  the 
sole. 

It  is  to  be  noted  that  the  integument  of  the  outer  side  of  the  heel 
and  outer  border  of  the  foot,  including  the  outer  side  of  the  little  toe, 
is  supplied  by  the  short  saphenous  nerve,  the  external  branch  of 
the  musculo-cutaneous  nerve  also  taking  part  in  the  supply  of 
the  outer  border,  whilst  the  integument  of  the  inner  border  of  the 
foot  is  supplied  by  the  long  saphenous,  and  by  the  internal  branch 
of  the  musculo-cutaneous  nerve. 

The  cutaneous  arteries  of  the  sole  are  branches  of  the  internal 
and  external  plantar  vessels,  and  in  their  course  and  distribution 
they  accompany  the  corresponding  cutaneous  nerves.  There  is  a 
very  copious  supply  of  arteries  to  the  integument  of  the  heel,  repre- 
sented by  the  internal  calcaneal  branches  of  the  external  plantar 
and  posterior  tibial  arteries  on  the  inner  side,  and  the  external 
calcaneal  branches  of  the  posterior  peroneal  artery  on  the  outer 
side. 

Superficial  Veins. — The  superficial  veins  are  very  numerous,  and 
are  for  the  most  part  arranged  in  the  form  of  a  plexus,  which  lies 
immediately  beneath  the  skin.  Besides  this  plexus,  there  is  a 
transverse  venous  arch  situated  near  the  clefts  of  the  toes.  The 
destination  of  the  venous  blood  of  the  plexus  and  transverse  arch 
is  the  dorsum  of  the  foot.  The  blood  is  conveyed  away  from  the 
plantar  subcutaneous  plexus  by  anterior  efferent  and  lateral  efferent 
vessels.  The  anterior  efferent  vessels  terminate  in  the  transverse 
venous  arch  near  the  clefts  of  the  toes.  The  lateral  efferent  vessels 
turn  round  the  outer  and  inner  borders  of  the  foot,  the  external 
set  terminating  in  the  short  saphenous  vein,  and  the  internal  set 
in  the  long  saphenous  vein,  just  where  these  vessels  are  springing 
from  the  extremities  of  the  dorsal  venous  arch.  The  transverse 
venous  arch  near  the  clefts  of  the  toes  receives  the  anterior  efferent 
vessels  of  the  plantar  subcutaneous  plexus,  and  the  plantar  digital 
veins.  The  blood  is  conveyed  away  from  it  by  means  of  efferent 
veins,  called  interdigilal,  which  i)ass  upwards  to  the  dorsum  of  the 


Si8  A  MANUAL  OF  ANATOMY 

foot,  where  they  terminate  in  the  dorsal  venous  arch.  The  super- 
ficial veins  of  the  sole  are  all  furnished  with  valves,  which  are  so 
placed  as  to  direct  the  flow  of  blood  to  the  dorsum  of  the  foot. 

Muscles. — The  muscles  of  the  sole  are  divided  into  four  layers — 
first,  second,  third,  and  fourth. 

First  Layer. — ^The  first  layer  consists  of  the  following  three 
muscles,  named  in  order  from  within  outwards  :  abductor  hallucis, 
flexor  brevis  digitorum,  and  abductor  minimi  digiti.  All  three  lie 
immediately  beneath  the  corresponding  divisions  of  the  plantar 
fascia,  each  muscle  having  a  compartment  to  itself. 

Abductor  Hallucis  —  Origin.  —  The  outer  head  arises  from 
(i)  the  internal  aspect  of  the  inner  tubercle  on  the  plantar  surface 
of  the  tuber  calcis  ;  (2)  the  deep  surface  of  the  internal  division 
of  the  plantar  fascia  ;  and  (3)  the  internal  intermuscular  septum, 
which  separates  it  from  the  flexor  brevis  digitorum.  Tlie  inner 
head  arises  from  (i)  the  lower  border  of  the  internal  annular 
ligament  on  its  deep  aspect  ;  and  (2)  the  fibrous  structures  along 
the  adjacent  part  of  the  inner  side  of  the  sole,  such  as  the  tendon 
of  the  tibialis  posticus  and  some  of  its  expansions. 

Insertion. — The  tubercular  enlargement  on  the  inner  side  of  the 
base  of  the  first  phalanx  of  the  great  toe. 

Nerve-suf'ply. — ^The  internal  plantar  nerve. 

Action. — (i)  To  abduct  the  great  toe  from  the  imaginary  middle 
line  of  the  foot,  which  passes  through  the  centre  of  the  second  toe  ; 
and  (2)  to  flex  the  metatarso-phalangeal  joint  of  the  great  toe. 
The  tendon  of  the  muscle  receives  on  its  outer  and  deep  aspect  the 
fleshy  inner  head  of  the  flexor  brevis  hallucis. 

Flexor  Brevis  Digitorum  (flexor  perforatus) — Origin. — (i)  The 
front  of  the  inner  tubercle  on  the  plantar  surface  of  the  tuber 
calcis  ;  (2)  the  deep  surface  of  the  central  division  of  the  plantar 
fascia  ;  and  (3)  the  intermuscular  septum  on  either  side. 

Insertion. — By  means  of  four  tendons  which  go  to  the  four  outer 
toes,  where  each  is  inserted  into  the  sides  of  the  shaft  of  the  second 
phalanx  at  its  centre  and  on  its  plantar  aspect. 

Nerve-supply. — ^The  internal  plantar  nerve. 

Action. — (i)  To  flex  the  second  phalanges  of  the  four  outer  toes, 
and  (2)  to  flex  the  metatarso-phalangeal  joints. 

Each  tendon,  as  it  passes  along  the  plantar  surface  of  a  toe,  has 
a  tendon  of  the  flexor  longus  digitorum  above  it  as  far  as  the 
second  phalanx,  the  two  tendons  occupying  a  fibro-osseous  canal 
lined  by  a  synovial  membrane  which  furnishes  a  separate  invest- 
ment for  each  tendon.  Opposite  the  first  phalanx  the  brevis  tendon 
divides  into  two  parts,  and  the  longus  tendon  passes  through  the 
cleft  thus  formed;  hence  the  name  flexor  perforatus  for  the  brevis 
muscle.  Thereafter  the  two  divisions  of  the  brevis  tendon  unite 
by  their  adjacent  margins  on  the  upper  or  deep  surface  of  the 
longus  tendon,  but  they  soon  separate  and  take  insertion  into  the 
sides  of  the  shaft  of  the  second  phalanx  at  its  centre  and  on  its 
plantar    aspect.     Each    brevis    tendon    has    a   ligamentum    breve 


THE  LOWER  LIMB 


S19 


Abductor  Minimi  Digiti . 


Outer  Digital  Branch  of 

External  Plantar  Nerve 

External  Plantar __,__._ 


Inner  Digital  Branch  of 
External  Plantar  Ner\'e 


Communicating  Nerve 

Flexor  Brevis  Minimi  — 
Digiti 


Central  Division  of  Plantar 

MWM  Fascia  (cut) 


Abductor  Hallucis 


i\        W  \1      Flexor  Brevis  Digitorum 


Internal  Plantar  Nerve 
and  Artery 


Flexor  Brevis  Hallucis 


Tendon  of  Flexor 
Longus  Hallucis 


Fig.  253.— The  First  Layer  of  Plantar  Muscles  (Left  Foot). 


520  A  MANUAL  OF  ANATOMY 

which  passes  between  its  upper  surface  near  its  final  division  and 
the  distal  end  of  the  first  phalanx.  The  fibrous  sheaths  of  the 
tendons,  as  they  pass  along  the  plantar  aspects  of  the  toes,  as 
well  as  the  accessories  of  these  sheaths,  correspond  with  those 
of  the  fingers.  As  the  long  and  short  flexor  tendons  are  about 
to  pass  to  the  plantar  aspects  of  the  respective  toes,  and  before 
entering  the  fibro  -  osseous  canals,  each  pair  of  tendons  passes 
through  a  short  fibrous  tunnel,  corresponding  in  position  with  the 
balls  of  the  toes,  and  constructed  in  the  following  manner  : 
superiorly  or  deeply  it  is  formed  by  a  portion  of  the  transverse 
metatarsal  ligament  ;  interiorly  or  superficially  by  a  digital  process 
of  the  central  division  of  the  plantar  fascia ;  and  on  either 
side  by  the  deep  expansion  of  the  digital  process  which  joins  the 
transverse  metatarsal  hgament  and  lateral  metatarso-phalangeal 
ligament. 

Abductor  Minimi  Digiti — Origin. — (i)  The  outer  side  and  front 
of  the  outer  tubercle  on  the  plantar  aspect  of  the  tuber  calcis  ; 
(2)  the  front  of  the  inner  tubercle  ;  (3)  the  external  intermuscular 
septum  ;  and  (4)  the  external  division  of  the  plantar  fascia, 
more  particularly  the  strong  band  which  extends  between  the 
outer  tubercle  of  the  os  calcis  and  the  tuberosity  on  the  outer  side 
of  the  base  of  the  fifth  metatarsal  bone. 

Insertion. — The  outer  side  of  the  base  of  the  first  phalanx  of  the 
little  toe,  in  conjunction  with  the  flexor  brevis  minimi  digiti.  It 
often  takes  attachment  also  to  the  base  of  the  fifth  metatarsal  bone 
on  the  outer  aspect  of  its  plantar  surface. 

Nerve-supply. — ^The  external  plantar  nerve. 

Action. — (i)  To  abduct  the  little  toe,  and '(2)  to  flex  its  metatarso- 
phalangeal joint. 

Occasionally  a  fourth  muscle  is  met  with  in  the  first  layer,  called  the 
abductor  ossis  metatarsi  quinti  or  Wood's  muscle.  It  arises  from  the  outer 
tubercle  on  the  plantar  aspect  of  the  tuber  calcis,  and  from  the  adjacent 
portion  of  the  plantar  fascia,  and  it  is  inserted  into  the  tuberosity  on  the 
outer  side  of  the  base  of  the  fifth  metatarsal  bone.  In  most  cases,  however, 
this  muscle  has  undergone  degeneration,  and  is  only  represented  by  the  strong 
band  of  the  external  division  of  the  plantar  fascia,  which  extends  between  the 
outer  calcaneal  tubercle  and  the  tuberosity  on  the  outer  side  of  the  base 
of  the  fifth  metatarsal  bone. 

Second  Layer. — ^This  layer  consists  partly  of  tendons  and  partly 
of  muscles.  They  are  as  follows :  the  tendon  of  the  flexor  longus 
hallucis  ;  the  tendon  of  the  flexor  longus  digitorum ;  the  flexor 
or  musculus  accessorius  ;  and  the  lumbricales. 

Tendons  of  Flexor  Longus  Hallucis  and  Flexor  Longus  Digitorum. 
— ^The  tendon  of  the  flexor  longus  hallucis,  after  leaving  the 
groove  on  the  under  surface  of  the  sustentaculum  tali  of  the 
OS  calcis,  is  directed  forwards  and  inwards,  lying  in  its  course 
between  the  two  heads  of  the  flexor  brevis  hallucis,  and  the 
tendon  of  the  flexor  longus  digitorum  is  directed  forwards  and  out- 
wards  towards   the  middle   line   of   the   sole.     The   two  tendons, 


THE  LOWER  LIMB 


521 


Abductor  Minimi 
Digiti 

Long  Plantar. 
Ligament 

Outer  Head  of  Flexor 
Accessorius 
External  Plantar. 

Arterj' 

External  Plantar 

Nerve 


Peroneus  Longus 


Tuberosity  of 
Fifth  Metatarsal 


Abductor  Minimi  . 
Digiti 
Flexor  Brevis 
Minimi  Digiti 

Fourth  Lumbri- . 
calls 


Tendon  of  Flexor 
Brevis  Digitorum' 


Flexor  Brevis  Digitorum 


Inner  Head  of  Flexor 
Accessorius 


-Internal  Plantar  Nerve 


Internal 
Plantar  Artery 

Flexor  Accessorius 


'*         .  Flexor  Longus 
Digitorum 


__■' Abductor  Hallucis 


.  Inner  Head  of  Flexor 
Brevis  Hallucis 

.Flexor  Longus 
Hallucis 


Fig.  254.' — The  Second  Layer  of  Plantar  Muscles  (Left  Foot). 


522  A  MANUAL  OF  ANATOMY 

therefore,  cross  each  other,  that  of  the  flexor  longus  hallucis  being 
above,  or  on  the  deep  surface  of,  the  other,  and  giving  a  shp  to  it. 
The  tendon  of  the  flexor  longus  digitorum,  on  reaching  the  middle 
line  of  the  sole,  receives  the  flexor  or  musculus  accessorius,  and 
thereafter  terminates  in  four  tendons  for  the  four  outer  toes,  with 
which  tendons  the  lumbricales  are  associated. 

Flexor  or  Musculus  Accessorius.  —  This  muscle  is  so  named 
because  it  is  accessory  to  the  long  flexor.  It  arises  by  two  heads, 
inner  and  outer,  which  embrace  between  them  the  os  calcis  and  the 
long  plantar  ligament. 

Origin. — The  inner  head  arises  from  the  internal  concave  surface 
of  the  OS  calcis  below  the  groove  on  the  under  surface  of  the  susten- 
taculum tali.  The  outer  head  arises  from  (i)  the  junction  of  the 
external  and  plantar  surfaces  of  the  os  calcis  in  front  of  the  outer 
tubercle  ;  and  (2)  the  adjacent  portion  of  the  long  plantar  ligament. 

Insertion. — ^The  outer  border  and  upper  surface  of  the  tendon 
of  the  flexor  longus  digitorum  about  the  centre  of  the  sole. 

Nerve-supply. — ^The  external  plantar  nerve. 

Action. — (i)  To  flex  the  terminal  phalanges  of  the  four  outer  toes, 
and  (2)  to  counteract  the  tendency  of  the  long  flexor  tendons  to 
draw  the  toes  inwards  during  flexion.  In  performing  this  latter 
action,  the  muscle  keeps  the  long  flexor  tendon  in  the  middle  line, 
so  that  its  four  divisions  act  in  a  straight  line  upon  the  toes. 

The  inner  head  of  the  muscle  is  broad  and  fleshy,  whilst  the  outer 
head  is  narrow,  pointed,  and  tendinous. 

This  muscle  is  to  be  regarded  as  a  detached  portion  of  the 
flexor  longus  digitorum,  forming  an  additional  tarsal  origin  for  the 
purpose  of  counteracting  the  obliquity  of  its  tendons. 

Lumbricales. — ^These  muscles  are  four  in  number. 

Origin. — From  the  tendons  of  the  flexor  longus  digitorum  where 
these  begin  to  diverge,  the  outer  three  taking  origin  each  from  the 
contiguous  sides  of  the  tendons  between  which  it  lies,  and  the  most 
internal  springing  only  from  the  inner  side  of  the  long  flexor  tendon 
destined  for  the  second  toe. 

Insertion. — ^The  tendons,  having  passed  round  the  inner  sides  of 
the  metatarso-phalangeal  joints  of  the  four  outer  toes,  take  insertion 
each  into  the  expansion  formed  by  the  extensor  tendon  on  the 
dorsal  aspect  of  the  first  phalanx. 

Nerve-supply. — ^The  most  internal  or  first  lumbricalis  is  supplied 
by  the  internal  plantar  nerve,  more  particularly  by  its  second 
digital  branch  on  its  way  to  the  cleft  between  the  great  toe  and  the 
second.  The  outer  three  lumbricales,  or  the  second,  third,  and 
fourth,  are  supplied  by  the  deep  division  of  the  external  plantar 
nerve. 

Action. — (i)  To  flex  the  metatarso-phalangeal  joint,  and  (2)  to 
extend  the  interphalangeal  joints. 

The  muscles  are  to  be  regarded  as  detached  portions  of  the  flexor 
longus  digitorum. 

Third  Layer. — The   third   layer   consists   of   the   following  four 


THE  LOWER  LIMB 


523 


Abductor  Minimi  Diariti irr^' 


Long  Plantar  Ligament ttV" 


Flexor  Accessorius 


Peroneus  Longus   — 
Peroneus  Brevis 


Fourth  Dorsal 
Interosseous 

Third  Plantar 
Interosseous     ^^ 
Abductor  Minimi  Digiti  ^ 

Flexor  Brevis  Minimi  _* 
Digiti 

Adductor  Transversus 
Hallucis 


Flexor  Brevis  Digitorum 


External  Plantar  Artery 
External  Plantar  Nerve 
Internal  Plantar  Nerve 


Abductor  Hallucis 


Internal  Plantar  Artery 
Tendon  of  Flexor  Longus 

Digitorum 
Tendon  of  Flexor  Longus 

Hallucis 

-   Origin  of  Flexor  Brevis 
Hallucis 


Adducto!  Obliquus  Hallucis 

Abductor  Hallucis 

Inner  Head  of  Flexor 
Brevis  Hallucis 

Outer  Head  of  Flexor 
Brevis  Hallucis 


Tendon  of  Flexor  Longus 
Hallucis 


Fig.  255.— The  Third  Lavek  of  Plantar  Muscles  (Left  Foot). 


524  A   MANUAL  OF  ANATOMY 

muscles :  flexor  brevis  hallucis ;  adductor  obliquus  hallucis ;  adductor 
transversus  hallucis  ;  and  flexor  brevis  minimi  digiti. 

Flexor  Brevis  Hallucis — Origin. — (i)  The  inner  part  of  the  plantar 
surface  of  the  cuboid  bone  (sometimes  the  internal  surface),  and 
(2)  the  expansions  of  the  tibialis  posticus  tendon  to  the  middle  and 
external  cuneiform  bones. 

Insertion. — By  means  of  two  heads,  outer  and  inner.  The  inner 
head  is  inserted  into  the  tubercular  enlargement  on  the  inner  side 
of  the  base  of  the  first  phalanx  of  the  great  toe,  in  conjunction  with 
the  abductor  hallucis.  The  outer  head  is  inserted  into  the  tuber- 
cular enlargement  on  the  outer  side  of  the  base  of  the  first  phalanx 
of  the  great  toe,  in  conjunction  with  the  adductor  obliquus  hallucis 
and  adductor  transversus  hallucis. 

Nerve-supply. — The  internal  plantar  nerve,  more  particularly  its 
first  or  most  internal  digital  branch. 

Action. — ^To  flex  the  metatarso-phalangeal  joint  of  the  great 
toe.  It  may  at  the  same  time  act  as  a  very  slight  adductor  of 
that  toe. 

The  flexor  brevis  hallucis  lies  along  the  outer  side  of  the  tendon 
of  the  abductor  hallucis.  It  is  tendinous  and  narrow  behind,  but 
soon  becomes  fleshy  and  divides  into  an  inner  and  outer  head  of 
insertion,  between  which  is  the  tendon  of  the  flexor  longus  hallucis. 
In  each  head  there  is  a  sesamoid  bone. 

Adductor  Obliquus  Hallucis  —  Origin. — (i)  The  sheath  of  the 
tendon  of  the  peroneus  longus,  and  (2)  the  plantar  surfaces  of  the 
bases  of  the  second,  third,  and  fourth  metatarsal  bones. 

Insertion. — ^The  tubercular  enlargement  on  the  outer  side  of  the 
base  of  the  first  phalanx  of  the  great  toe,  in  conjunction  with  the 
outer  head  of  the  flexor  brevis  hallucis  on  the  inner  side  and  the 
adductor  transversus  hallucis  on  the  outer  side. 

Nerve-siipply. — The  deep  division  of  the  external  plantar  nerve. 

Action. — (i)  To  adduct  the  great  toe,  and  (2)  to  flex  the  meta- 
tarso-phalangeal joint. 

The  muscle  lies  obliquely  on  the  outer  side  of  the  flexor  brevis 
hallucis. 

Adductor  Transversus  Hallucis  (transversalis  pedis) — Origin. — 
(i)  The  inferior  metatarso-phalangeal  ligaments  of  the  third,  fourth, 
and  fifth  toes,  and  (2)  the  transverse  metatarsal  ligament. 

Insertion. — The  tubercular  enlargement  on  the  outer  side  of  the 
base  of  the  first  phalanx  of  the  great  toe,  in  conjunction  with  the 
adductor  obliquus  hallucis. 

Nerve-supply. — The  deep  division  of  the  external  plantar  nerve. 

Action. — (i)  To  adduct  the  great  toe,  and  (2)  to  approximate 
the  toes  to  each  other. 

The  muscle  consists  of  three  fleshy  bundles  which  join  into 
one,  and  it  lies  transversely  upon  the  heads  of  the  four  outer 
metatarsal  bones.  It  is  to  be  regarded  as  a  detached  portion  of 
the  adductor  obliquus  hallucis,  which  has  become  shifted  forwards 
to  the  balls  of  the  toes. 


THE  LOWER  LIMB 


525 


Flexor  Brevis  Minimi  Digiti — Origin. — (i)  The  plantar  surface 
of  the  base  of  the  fifth  metatarsal  bone,  and  (2)  the  sheath  of  the 
tendon  of  the  peroneus  longus. 

Insertion. — The  outer  side  of  the  base  of  the  first  phalanx  of  the 
little  toe,  in  exjunction  with  the  abductor  minimi  digiti.  A  few 
of  the  fibres  also  take  attachment  to  the  plantar  surface  of  the  shaft 
of  the  fifth  metatarsal  bone  over  its  anterior  part.  These  fibres 
represent  the  muscle  called  opponens  minimi  digiti,  the  origin  of 
which  corresponds  with  those  fibres  of  the  flexor  brevis  minimi 
digiti  which  spring  from  the  sheath  of  the  tendon  of  the  peroneus 
longus. 

Nerve-supply. — The  superficial  division  of  the  external  plantar 
nerve,  and  usually  the  outer  digital  branch  of  that  division  to  the 
outer  side  of  the  little  toe. 

Action. — To  flex  the  metatarso-phalangeal  joint  of  the  little  toe. 
The  muscle  is  a  small  fleshy  slip  which  lies  upon  the  plantar  surface 
of  the  fifth  metatarsal  bone,  under  cover  of  the  abductor  minimi 
digiti.  It  is  liable  to  be  taken  for  a  plantar  interosseous  muscle, 
lying,  as  it  does,  in  close  contact  with  the  most  external  plantar 
interosseous. 

Plantar  Triangle. — This  is  a  muscular  triangle  in  connection  with 
the  third  layer  of  muscles,  the  boundaries  of  which  are  as  follows  : 
Anterior  or  Base. — Adductor  transversus  hallucis.  Internal. — 
Adductor  obliquus  hallucis.  External.  —  Flexor  brevis  minimi 
digiti.  Floor. — Portions  of  the  plantar  and  dorsal  interosseous 
muscles,  covered  by  the  interosseous  fascia.  Roof. — The  long  flexor 
tendons  and  the  lumbricales.  Contents. — (i)  A  limited  portion  of 
the  deep  part  of  the  external  plantar  artery ;  (2)  some  of  the  digital 
branches  of  the  plantar  arch,  especially  the  second  and  third,  and 
the  corresponding  veins  ;  and  (3)  a  limited  portion  of  the  deep 
division  of  the  external  plantar  nerve. 

Fourth  Layer. — The  fourth  layer  consists  of  the  interosseous 
muscles  ;  the  tendon  of  the  peroneus  longus  ;  and  the  tendon  of  the 
tibialis  posticus. 

Interosseous  Muscles. — The  interosseous  muscles  are  seven  in 
num.ber,  and  are  arranged  in  two  groups — plantar,  of  which  there 
are  three,  and  dorsal,  of  which  there  are  four.  The  plantar  muscles 
are  seen  only  in  the  sole,  but  the  dorsal  muscles  are  seen  on  the 
dorsum  of  the  foot  as  well  as  in  the  sole.  The  plantar  aspects  of 
the  muscles  are  covered  by  the  thin  interosseous  fascia  which  joins 
anteriorly  the  transverse  metatarsal  ligament. 

Plantar  Interossei. — These  belong  to  the  three  outer  toes,  and 
are  named  first,  second,  and  third  from  within  outwards. 

Origin. — (i)  The  inner  surfaces  of  the  shafts  of  the  third,  fourth, 
and  fifth  metatarsal  bones,  and  (2)  the  sheath  of  the  tendon  of  the 
peroneus  longus. 

Insertion. — (i)  The  inner  sides  of  the  bases  of  the  first  j)ha]anges 
of  the  third,  fourth,  and  fifth  toes,  and  (2)  the  expansions  formed 
by  the  long  and  short  extensor  tendons  (in  the  case  of  the  fifth  toe 


526 


A  MANUAL  OF  ANATOMY 


long  extensor  only)  on  the  dorsal  aspects  of  the  first  phalanges  of 
the  same  toes. 

Dorsal  Interossei. — These  belong  to  the  second,  third,  and  fourth 
toes,  the  second  toe  having  two.  They  are  named  first,  second, 
third,  and  fourth,  from  within  outwards. 

Origin. — Each  muscle  arises  by  two  heads  from  the  adjacent  lateral 
surfaces  of  the  shafts  of  the  metatarsal  bones  between  which  it  is 
situated,  but  more  extensively  from  the  metatarsal  bone  of  the  toe 
upon  which  the  muscle  acts  than  from  the  other  bone.  In  the  case 
of  the  first  (most  internal)  muscle  its  inner  head  is  comparatively 
smaU,  and  arises  from  the  outer  side  of  the  base  of  the  first  meta- 
tarsal bone,  as  well  as  from  the  adjacent  portion  of  the  internal 
cuneiform. 


Fig.  256. — The  Interosseous  Muscles  of  the  Right  Foot. 
A,  Plantar;  B,  Dorsal. 


Insertion. — The  dorsal  interossei  are  inserted  in  a  manner  pre- 
cisely similar  to  the  plantar  interossei.  The  first  and  second  dorsal 
interossei  belong  to  the  second  toe,  one  on  either  side  ;  the  third 
belongs  to  the  outer  side  of  the  third  toe ;  and  the  fourth  to  the 
outer  side  of  the  fourth  toe.  In  the  case  of  all  the  interosseous 
muscles  the  insertion  into  a  first  phalanx  is  comparatively  slight, 
the  chief  insertion  being  into  the  expansion  of  the  extensor  tendon 
on  the  dorsal  aspect  of  the  first  phalanx. 

Nerve- supply. — The  external  plantar  nerve  in  the  following 
manner:  the  deep  division  of  .the  nerve  usually  supplies  the  inter- 
osseous muscles,  with  the  exception  of  the  two  which  occupy  the 
fourth  (most  external)  interosseous  space,  namely,  the  fourth 
dorsal  and  third  plantar.  These  two  are  usually  supplied  by  the 
outer  digital  branch  of  the  superficial  division  of  the  external  plantar 


THE  LOWER  LIMB 


527 


nerve  to  the  outer  side  of  the  httle  toe.  Sometjmes,  however,  the 
deep  division  of  the  nerve  supphes  all  seven  interosseous  muscles. 
In  all  cases  the  nerves  enter  the  muscles  on  their  plantar  aspects. 

Action — Plantar  Interossei. — These  are  adductors,  the  toes  which 
they  adduct  being  the  third,  fourth,  and  fifth.  Dorsal  Interossei. — 
These  are  abductors,  the  toes  which  they  abduct  being  the  second, 
third,  and  fourth. 

In  speaking  of  adduction  and  abduction  in  the  case  of  the  foot, 
reference  is  made  to  an  imaginary  line  passing  through  the  centre 
of  the  second  toe,  adduction  being  movement  towards  that  line, 
and  abduction  movement  from  it. 

The  first  and  second  dorsal  interossei,  acting  both  upon  the  second 
toe,  abduct  it  from  the  imaginary  line  passing  through  its  centre, 
the  first  abducting  it  to  the  inner  side  and  the  second  to  the  outer 
side.  The  third  and  fourth  dorsal  interossei  abduct  the  third  and 
fourth  toes. 

The  interosseous  muscles,  aided  by  the  lumbricales,  also  act  as 
follows  :  (i)  they  flex  the  metatarso-phalangeal  joints  of  the  four 
outer  toes,  and  (2)  they  extend  the  interphalangeal  joints  of  these 
toes. 

The  tendons  of  the  peroneus  longus  and  tibialis  posticus  have 
been  already  described. 

Plantar  Nerves. — The  plantar  nerves  are  two  in  number,  internal 
and  external.  They  are  the  terminal  branches  into  which  the 
posterior  tibial  nerve  divides  on  a  level  with  the  lower  border  of 
the  internal  annular  ligament,  though  the  division  frequently 
takes  place  on  a  level  with  the  upper  border  of  that  ligament,  or 
at  some  point  beneath  it.  The  internal  plantar  is  the  larger  of 
the  two  nerves,  and  it  accompanies  the  internal  plantar  artery, 
which  is  the  smaller  of  the  two  plantar  arteries.  The  external 
plantar  nerve  accompanies  the  external  plantar  artery. 

Internal  Plantar  Nerve. — This  nerve  has  a  wider  cutaneous,  but 
a  more  limited  muscular,  distribution  than  the  external  plantar. 
From  its  origin  it  passes  forwards  on  the  outer  side  of  the  internal 
plantar  artery,  being  at  first  under  cover  of  the  abductor  hallucis, 
and  subsequently  lying  between  that  muscle  and  the  flexor  brevis 
digitorum.  About  the  middle  (in  length)  of  the  foot  it  divides 
into  its  terminal  branches. 

Branches. — These  are  muscular,  articular,  plantar  cutaneous,  and 
digital. 

The  muscular  branches  supply  the  abductor  hallucis  and  flexor 
brevis  digittjrum. 

The  articular  branches  are  distributed  to  the  astragalo-navicular 
and  naviculo-cuneiform  articulations. 

The  plantar  cutaneous  branches  are  distributed  to  the  integu- 
ment ol  thi-  inner  hall  of  tlic  s(jle. 

The  digital  branches  are  four  in  number,  and  are  named  first, 
second,  third,  and  lourth  from  within  outwards.  The  first  is  a 
single  nerve,  but  the  other  three  are  compound.     The  first  digital 


S28 


A  MANUAL  OF  ANATOMY 


nerve  is  distributed  to  the  inner  side  of  the  great  toe,  and  it 
furnishes  a  branch  to  the  flexor  brevis  hallucis  muscle.  The 
second  digital  nerve  gives  off  a  twig  to  the  first  lumbricalis,  and 
near  the  cleft  between  the  great  toe  and  the  second  it  divides  into 
two  collateral  plantar  digital  nerves,  which  supply  the  contiguous 
sides  of  these  two  toes.  The  third  digital  nerve  divides  near  the 
cleft  between  the  second  and  third  toes  into  two  collateral  plantar 
digital  nerves,  which  supply  the  contiguous  sides  of  these  two  toes. 
The  fourth  digital  nerve  also  divides  near  the  cleft  between  the 
third  and  fourth  toes  into  two  collateral  plantar  digital  nerves, 
which  supply  the  contiguous  sides  of  these  two  toes.  Before 
dividing,  it  communicates  by  a  twig  with  that  digital  branch  of  the 
superficial  division  of  the  external  plantar  which  supplies  the  con- 


Calcaneo-plantar  of  Posterior^-t — 
Tibial 

Internal  Plantar. 


Branches  of  Internal  Saphenous,' 


Branch  to  Flexor  Brevis  Hallucis, 
Branch  to  First  Lumbricalis- 


Branches  of  External  Saphenous 


External  Plantar 
Superficial  Branch 
Deep  Branch 


Fig.  257. — Diagram  of  the  Nerves  of  the  Foot  (Plantar  Aspect). 

tiguous  sides  of  the  fourth  and  fifth  toes.  The  nerves  on  the  sides 
of  the  toes  are  placed  below  the  digital  arteries.  They  furnish 
articular  branches  to  the  joints  of  the  toes  and  cutaneous  branches 
to  the  plantar  and  dorsal  surfaces  of  the  toes.  Finally  each  ter- 
minates in  two  branches — one  to  the  matrix  of  the  nail,  and  the  other 
to  the  pulp  of  the  toe.  The  branches  of  the  digital  nerves  are  beset 
with  numerous  Pacinian  bodies. 


Summary  of  the  Internal  Plantar  Nerve. — Muscular  branches  to  abductor 
hallucis,  flexor  brevis  digitorum,  flexor  brevis  hallucis,  and  first  lumbricalis. 
Cutaneous  branches  to  the  integument  of  the  inner  half  of  the  sole  and  the 
inner  three  and  a  half  toes.  Articular  branches  to  the  astragalo-navicular, 
naviculo-cuneiform,  and  digital  articulations. 

The  internal  plantar  nerve  in  its  digital  distribution  corresponds  closely 


THE  LOWER  LIMB  529 

with  the  median  nerve  in  the  hand.  There  is  this  difference,  however,  between 
these  two  nerves  :  the  internal  plantar  has  one  single  digital  nerve  and  three 
compound  digital  nerves,  whereas  the  median  has  three  single  digital  nerves 
and  two  which  are  compound. 

External  Plantar  Nerve. — This  nerve  has  a  more  Hmited  cutaneous, 
but  a  wider  muscular,  distribution  than  the  internal  plantar.  From 
its  origin  it  is  directed  forwards  and  outwards  to  the  base  of  the 
fifth  metatarsal  bone,  where  it  breaks  up  into  two  divisions,  super- 
ficial and  deep.  In  this  course  it  lies  at  first  between  the  flexor 
brevis  digitorum  and  flexor  or  musculus  accessorius,  and  subse- 
quently in  the  groove  between  the  former  muscle  and  the  abductor 
minimi  digiti.  It  is  close  to  the  inner  side  of  the  external  plantar 
artery,  and  occupies  the  concavity  of  the  curve  described  by  that 
vessel.     This  part  of  the  nerve  is  spoken  of  as  the  trunk. 

Branches  of  the  Trunk. — The  branches  are  as  follows  :  muscular 
to  the  flexor  or  musculus  accessorius  and  abductor  minimi  digiti ; 
articular  to  the  calcaneo-cuboid  articulation  ;  cutaneous  to  the 
mtegument  of  the  outer  half  of  the  sole ;  and  terminal. 

The  terminal  branches  are  two  in  number,  superficial  and  deep, 
and  they  spring  from  the  trunk  at  the  base  of  the  fifth  metatarsal 
bone. 

The  superficial  division  furnishes  two  digital  nerves,  outer  and 
inner.  The  outer  digital  nerve  is  single,  and  is  distributed  to  the 
outer  side  of  the  little  toe,  supplying  branches  to  the  flexor  brevis 
minimi  digiti  and,  as  a  general  rule,  to  the  interosseous  muscles 
of  the  fourth  interosseous  space,  namely,  the  fourth  dorsal  and 
the  third  plantar.  It  may,  however,  fail  to  supply  these  two 
interosseous  muscles,  in  which  case  they  derive  their  nerve-supply 
from  the  deep  division  of  the  external  plantar  nerve.  The  inner 
digital  nerve  is  compound.  In  its  forward  course  it  communicates 
by  a  twig  with  the  most  external  digital  branch  of  the  internal 
plantar  nerve  which  supplies  the  contiguous  sides  of  the  third  and 
fourth  toes,  and  near  the  cleft  between  the  fourth  and  fifth  toes  it 
divides  into  two  collateral  plantar  digital  nerves,  which  supply  the 
contiguous  sides  of  these  two  toes.  The  digital  branches  of  the 
superficial  division  of  the  external  plantar  nerve  resemble  in  all 
respects  those  of  the  internal  plantar. 

The  deep  division  is  muscular  and  articular  in  its  distribution. 
It  sinks  deeply  into  the  sole  with  the  external  plantar  artery  as 
that  vessel  forms  the  plantar  arch.  Its  direction  is  inwards  and 
forwards  on  the  deep  or  superior  surface  of  the  musculus  acces- 
sorius, long  flexor  tendons  and  lumbricales,  and  adductor  obliquus 
hallucis,  and  lying  upon  the  bases  of  the  second,  third,  and  fourth 
metatarsal  bones. 

Branches. — The  branches  of  the  deep  division  are  muscular, 
articular,  and  perforating. 

The  muscular  branches  supply  (i)  the  interosseous  muscles, 
plantar  and  dorsal,  with  the  exception,  as  a  general  rule,  of  the 
two   which    occuj>y    tlie    fourth    interosseous   space,    namely,    the 

34 


530  A   MANUAL  OF  ANATOMY 

fourth  dorsal  and  third  plantar — though  these  two  may  be  in- 
cluded ;  (2)  the  outer  three  lumbricales  ;  (3)  the  adductor  trans- 
versus  hallucis  ;  and  (4)  the  adductor  obliquus  hallucis. 

The  articular  branches  supply  the  tarsal  and  tarso-metatarsal 
articulations.  They  sometimes  also  supply  the  metatarso-phalangeal 
articulations. 

The  perforating  branches  pass  upwards  through  the  proximal 
parts  of  the  interosseous  spaces,  and  join  the  interosseous  branches 
of  the  dorsalis  pedis  nerve. 

Summary  of  External  Plantar  Nerve.  —  Muscular  branches  to  the  flexor 
or  musculus  accessorius,  abductor  minimi  digiti,  flexor  brevis  minimi  digiti, 
all  seven  interossei,  outer  three  lumbricales,  adductor  transversus  hallucis, 
and  adductor  obliquus  hallucis.  Cutaneous  branches  to  the  integument  of 
the  outer  half  of  the  sole  and  the  outer  one  and  a  half  toes.  Articular  branches 
to  the  tarsal,  tarso-metatarsal,  and,  in  some  cases,  metatarso-phalangeal 
articulations.  Perforating  branches  to  join  the  interosseous  nerves  on  the 
dorsum  of  the  foot. 

The  external  plantar  nerve  corresponds  with  the  ulnar  nerve  in  the  hand. 

Plantar  Arteries. — The  arteries  of  the  sole  of  the  foot  are  three  in 
number,  namely,  the  internal  plantar,  the  external  plantar,  and 
the  plantar  branch  of  the  arteria  dorsalis  pedis.  The  internal  and 
external  plantar  arteries  are  the  terminal  branches  into  which  the 
posterior  tibial  divides  on  a  level  with  the  lower  border  of  the 
internal  annular  ligament.  The  internal  plantar  is  much  smaller 
than  the  external,  and  each  vessel  is  accompanied  by  the  corre- 
sponding plantar  nerve. 

Internal  Plantar  Artery.  —  This  vessel  passes  forwards  along 
the  inner  side  of  the  sole  with  the  internal  plantar  nerve,  which  lies 
on  its  outer  side,  and  it  usually  terminates  on  the  inner  aspect  of 
the  metatarso-phalangeal  joint  of  the  great  toe  by  anastomosing 
with  the  digital  branch  of  the  arteria  magna  or  princeps  hallucis 
to  the  inner  side  of  that  toe.  It  is  at  first  under  cover  of  the 
abductor  hallucis,  and  subsequently  lies  between  that  muscle  and 
the  flexor  brevis  digitorum.  It  is  accompanied  by  two  venge 
comites. 

Branches. — These  are  as  follows  : 

Muscular  to  the  muscles  in  its  immediate  vicinity. 

Cutaneous  to  the  integument  of  the  inner  half  of  the  sole. 

Articular  to  the  articulations  along  the  inner  side  of  the 
foot. 

The  internal  tarsal  branches  pass  inwards  beneath  the  abductor 
hallucis  to  the  inner  border  of  the  foot,  where  they  anastomose 
with  the  internal  tarsal  branches  of  the  arteria  dorsalis  pedis. 

The  superficial  digital  arteries  are  three  in  number,  and  are  usually 
very  small.  They  accompany  the  three  compound  digital  branches 
of  the  internal  plantar  nerve  to  the  clefts  where  these  nerves  divide 
into  their  collateral  branches,  and  there  they  terminate  by  joining 
the  inner  two  digital  arteries  from  the  plantar  arch  and  the  arteria 
magna  or  princeps  hallucis. 


THE  LOWER  LIMB 


531 


External  Plantar  Artery,  —  This  vessel,  which  is  much  larger 
than  the  internal  plantar,  arises  from  the  posterior  tibial  artery 
on  a  level  with  the  lower  border  of  the  internal  annular  ligament, 


Internal  Calcaneal  Artery 

, Posterior  Tibial  Artery 


External  Plantar  Artery 


Peroneus  Brevis  _. 


Posterior  Perforating. 

Artery 

First  Digital  Artery. 

Plantar  Arch. 

Second  Digital  A.. 

Third  Digital  A.. 

Fourth  Digital  A. 


Anterior  Perforating 
Artery 


^Internal  Plantar  Artery 


•Tibialis  Posticus 


Flex.  Longus  Digitorum 


Flex.  Longus  Hallucis 
Flexor  Accessorius 


-Tendon  of  Abd.  Hallucis 

Plantar  Branch  of 
-  -Dorsalis  Pedis  Artery 
-Communicating  Branch 


"—4 —  Arteria  Magna  Hallucis 


Fk;.  258. — The  Plantar  Arteries  (Left  Foot)   (after  L.  Testut's 
'  Anatomie  Humaine'). 

and  terminates  at  the  proximal  part  of  the  first  interosseous  space 
by  anastomosing  with  the  communicating  branch  of  the  plantar 
division  of  the  arteria  dorsalis  pedis. 

34—2 


532  A  MANUAL  OF  ANATOMY 

The  artery  is  accompanied  by  the  external  plantar  nerve  through- 
out its  whole  course,  and  by  two  vense  comites.  At  its  origin  it  is 
situated  on  the  inner  surface  of  the  os  calcis,  from  which  point  it  is 
directed  outwards  and  forwards  across  the  sole  to  the  base  of  the 
fifth  metatarsal  bone.  It  here  describes  a  sharp  bend,  and,  sinking 
deeply,  it  recrosses  the  sole  on  its  way  to  the  proximal  part  of  the 
first  interosseous  space.  The  vessel  is  divided  into  two  parts, 
first  and  second.  These  two  parts  together  describe  one  great 
curve,  the  concavity  of  which  looks  inwards  and  is  occupied  by  the 
external  plantar  nerve. 

The  first  part  extends  from  the  lower  border  of  the  internal 
annular  ligament  to  the  base  of  the  fifth  metatarsal  bone.  Its 
course  may  be  indicated  by  drawing  a  line  from  a  point  midway 
between  the  tip  of  the  internal  malleolus  and  the  inner  tubercle  on  the 
plantar  aspect  of  the  tuber  calcis  to  the  base  of  the  fifth  metatarsal 
bone.     The  direction  of  this  part  is  outwards  and  forwards. 

Relations. — It  is  covered  in  succession  by  the  abductor  hallucis, 
flexor  brevis  digitorum,  and  finally  only  by  the  skin,  superficial 
fascia,  and  plantar  fascia.  It  rests  upon  the  os  calcis  and  the 
musculus  accessorius. 

It  is  to  be  noted  that  this  part  of  the  vessel  is  very  superficial  for  a 
short  distance  close  to  the  base  of  the  fifth  metatarsal  bone,  where  it 
lies  between  the  flexor  brevis  digitorum  and  abductor  minimi  digiti. 

The  second  part  extends  from  the  base  of  the  fifth  metatarsal 
bone  to  the  proximal  part  of  the  first  interosseous  space.  Its 
course  may  be  indicated  by  a  line  connecting  the  limits  of  this  part 
of  the  vessel.  It  is  directed  inwards  and  forwards  in  a  slightly 
curved  manner,  with  the  convexity  of  the  curve  forwards,  and  thus 
it  forms  the  plantar  arch,  which  is  completed  by  the  communicating 
branch  of  the  plantar  division  of  the  arteria  dorsalis  pedis.  The 
second  part  is  accompanied  by  the  deep  division  of  the  external 
plantar  nerve,  and  is  very  deeply  placed. 

Relations. — It  is  covered  by  the  skin,  superficial  fascia,  central 
division  of  the  plantar  fascia,  flexor  brevis  digitorum,  flexor  longus 
digitorum,  lumbricales,  and  adductor  obliquus  hallucis.  It  rests 
upon  the  bases  of  the  second,  third,  and  fourth  metatarsal  bones 
and  the  corresponding  interosseous  muscles. 

Branches  of  the  First  Part. — ^The  branches  are  as  follows  : 

Muscular  to  the  muscles  in  its  immediate  vicinity. 

The  internal  calcaneal  branches  are  two  or  three  in  number. 
After  piercing  the  origin  of  the  abductor  hallucis,  they  reach  the 
inner  surface  of  the  os  calcis,  where  they  anastomose  with  the 
internal  calcaneal  branch  of  the  posterior  tibial  artery.  Over  the 
prominence  of  the  heel  they  also  anastomose  freely  with  the 
external  calcaneal  branches  of  the  posterior  peroneal  artery. 

Cutaneous  to  the  integument  of  the  outer  half  of  the  foot. 

Branches  also  turn  round  the  outer  border  of  the  foot,  where 
they  anastomose  with  the  tarsal  and  metatarsal  branches  of  the 
arteria  dorsalis  pedis  and  with  the  posterior  peroneal  artery. 


THE  LOWER  LIMB  533 

Branches  of  the  Second  Part. — The  branches  of  the  second  part, 
or  plantar  arch,  are  as  follows :  articular,  posterior  perforating,  and 
digital. 

The  articular  branches  arise  from  the  concavity  of  the  arch, 
and  pass  backwards  to  supply  the  tarsal  articulations. 

The  posterior  perforating  arteries,  which  are  three  in  number, 
arise  from  the  upper  aspect  of  the  arch.  They  pass  upwards  through 
the  proximal  parts  of  the  three  outer  interosseous  spaces,  and 
between  the  two  heads  of  the  corresponding  dorsal  interosseous 
muscles.  On  reaching  the  dorsum  of  the  foot  they  anastomose 
with  the  dorsal  interosseous  branches  of  the  metatarsal  artery, 
which  is  a  branch  of  the  arteria  dorsalis  pedis. 

The  digital  arteries  are  four  in  number — first,  second,  third, 
and  fourth,  from  without  inwards.  They  arise  from  the  front 
or  convexity  of  the  arch  and  pass  forwards.  The  first,  which  is  a 
single  artery,  lies  over  the  fifth  metatarsal  bone  and  flexor  brevis 
minimi  digiti.  The  second,  third,  and  fourth,  which  are  compound 
arteries,  are  placed  over  the  fourth,  third,  and  second  interosseous 
spaces  respectively,  where  they  lie  upon  the  corresponding  inter- 
osseous muscles.  The  first  is  distributed  to  the  outer  side  of  the 
little  toe,  of  which  it  is  the  plantar  digital  artery.  The  second, 
third,  and  fourth  pass  over  the  deep  surface  of  the  adductor 
transversus  hallucis,  and  bifurcate  near  the  clefts  between  the  four 
outer  toes,  each  dividing  into  two  collateral  plantar  digital  arteries. 
Those  of  the  second  supply  the  contiguous  sides  of  the  fourth  and 
fifth  toes,  those  of  the  third  the  contiguous  sides  of  the  third  and 
fourth  toes,  and  those  of  the  fourth  the  contiguous  sides  of  the 
second  and  third  toes.  Each  of  the  inner  three  digital  arteries  at 
its  point  of  bifurcation  gives  off  an  anterior  perforating  artery. 
These  anterior  perforating  arteries  pass  upwards  through  the 
distal  ends  of  the  outer  three  interosseous  spaces,  and,  on  reaching 
the  dorsum  of  the  foot,  anastomose  with  the  dorsal  interosseous 
arteries.  The  inner  two  (third  and  fourth)  digital  arteries  are  joined 
near  the  clefts  of  the  toes  by  the  outer  two  superficial  digital 
branches  of  the  internal  plantar  artery. 

On  the  sides  of  the  toes  the  plantar  digital  arteries  furnish  branches 
to  the  flexor  tendons  and  their  sheaths,  and  anastomose  freely 
with  the  dorsal  digital  arteries.  Near  the  distal  end  of  the  first  and 
second  phalanx,  and  on  the  plantar  aspect  of  each,  the  plantar- 
digital  arteries  of  opposite  sides  form  arches  from  which  articular 
twigs  are  given  to  the  interphalangeal  articulations,  and  on  the 
plantar  asjjcct  of  the  terminal  phalanx  they  end  by  forming  another 
arch.  From  this  latter  arch  branches  are  furnished  to  the  pulp 
of  the  toe  and  matrix  of  the  nail.  Each  digital  artery  is  accom- 
panied by  two  vena  comites.  The  external  plantar  artery 
corresponds  with  the  deep  branch  of  the  ulnar  artery  in  the 
palm. 

It  has  been  seen  that  the  plantar  arch,  by  means  of  its  four 
digital  branches,  supplies  the  outer  three  and  a  half  toes.     There 


S34  A  MANUAL  OF  ANATOMY 

thus  remain  one  and  a  half  to  be  accounted  for,  namely,  both  sides 
of  the  great  toe  and  the  inner  side  of  the  second  toe. 

Plantar  or  Perforating  Branch  of  Arteria  Dorsalis  Pedis. — This 
artery  is  one  of  the  terminal  branches  of  the  arteria  dorsalis  pedis. 
Having  entered  the  sole  through  the  proximal  part  of  the  first 
interosseous  space,  between  the  two  heads  of  the  first  dorsal  inter- 
osseous muscle,  it  immediately  divides  into  two  branches — com- 
mimicating  and  arteria  magna  or  princeps  hallucis. 

The  communicating  branch  is  a  short  vessel,  which  ends  by 
joining  the  second  part  of  the  external  plantar  artery  to  complete 
the  plantar  arch. 

The  arteria  magna  or  princeps  hallucis  is  the  fifth  plantar 
digital  artery.  Commencing  at  the  proximal  end  of  the  first  inter- 
osseous space  it  passes  forwards  over  the  plantar  aspect  of  that 
space  and  the  corresponding  dorsal  interosseous  muscle  towards 
the  cleft  between  the  great  toe  and  second  toe..  In  this  part  of  its 
course  it  furnishes  a  single  plantar  digital  artery,  which,  having 
crossed  the  first  metatarsal  bone,  beneath  the  tendon  of  the  flexor 
longus  hallucis,  is  distributed  to  the  inner  side  of  the  great  toe. 
Near  the  cleft  between  the  great  toe  and  second  toe  it  receives  the 
innermost  superficial  digital  branch  of  the  internal  plantar  artery, 
and  then  divides  into  two  collateral  plantar  digital  arteries  for  the 
supply  of  the  contiguous  sides  of  these  two  toes.  Before  dividing, 
it  communicates  with  the  arteria  dorsalis  hallucis  by  an  anterior 
perforating  branch,  which  passes  through  the  distal  end  of  the  first 
interosseous  space. 

Varieties — i.  Internal  Plantar  Artery. — This  vessel  is  sometimes  very  small, 
and  it  may  then  terminate  in  the  flexor  brevis  hallucis.  In  other  cases  it  is 
of  fairly  large  size,  and  then  it  may  replace  the  arteria  magna  or  princeps 
hallucis,  and  furnish  the  plantar  digital  branches  for  both  sides  of  the  great 
toe  and  the  inner  side  of  the  second  toe.  In  very  rare  cases  the  internal 
plantar  artery  communicates  with  the  external  plantar,  and  so  forms  a  super- 
ficial plantar  arch.  In  such  cases  the  superficial  digital  arteries  arise  from 
this  arch. 

2.  External  Plantar  Artery. — This  artery  is  liable  to  be  diminished  in  size, 
and  this  may  occur  to  such  an  extent  as  to  exclude  it  from  any  share  in  the 
plantar  arch.  Such  deficiencies  are  compensated  for  by  an  enlargement  of 
the  arteria  dorsalis  pedis  and  its  plantar  branch. 

The  posterior  perforating  branches  of  the  plantar  arch  are  sometimes  of 
comparatively  large  size,  and  then  they  furnish  the  dorsal  interosseous 
arteries  after  they  reach  the  dorsum  of  the  foot. 

For  the  tendon  of  the  peroneus  longus  in  the  sole  see  p.  488. 

Tendons  Involved  in  Club-foot. 

The  chief  varieties  of  club-foot  are  as  follows  :  talipes  equinus,  talipes 
varus,  talipes  equino-varus,  talipes  valgus,  talipes  calcaneus,  and  talipes 
calcaneo- valgus. 

Talipes  Equinus. — In  this  variety  the  foot  is  extended  upon  the  leg,  the 
heel  being  raised  from  the  ground,  so  that  the  person  walks  upon  the  toes. 
The  chief  tendons  involved  are  (i)  the  tendo  Achillis,  and  (2)  the  plantaris 
tendon.     The  latter,  however,  is  insignificant. 

Talipes  Varus. — In  this  variety  the  inner  border  of  the  foot  is  raised  so 
a,s  to  invert  the  sole,  and  the  foot  is  at  the  same  time  slightly  extended  upon 


THE  LOWER  LIMB 


535 


the  leg,  so  that  the  person  walks  upon  the  outer  border  of  the  foot.  The  chief 
tendons  involved  are  those  of  the  tibialis  anticus  and  tibialis  posticus. 

Talipes  Equino-varus. — This  is  a  combination  of  talipes  equinus  and  talipes 
varus,  the  heel  being  raised  as  well  as  the  inner  border  of  the  foot.  The 
chief  tendons  involved  are  as  follows  :  (i)  tibialis  posticus,  (2)  tibialis  anticus, 
(3)  tendo  Achillis,  and  (4)  plantaris.  In  addition  to  these  tendons  the 
abductor  hallucis  and  the  plantar  fascia  are  usuallj^  implicated. 

Talipes  Valgus. — In  this  variety  the  outer  border  of  the  foot  is  raised  so  as 
to  evert  the  sole,  and  the  person  walks  upon  the  inner  border  of  the  foot. 
The  tendons  involved  are  those  of  the  peroneus  longus  and  peroneus  brevis. 

Talipes  Calcaneus. — In  this  variety  the  foot  is  flexed  upon  the  leg,  the  toes 
being  raised,  so  that  the  person  walks  upon  the  heel.  The  tendons  involved 
are  as  follows  :  (i )  extensor  longus  digitorum,  (2)  peroneus  tertius,  (3)  extensor 
proprius  hallucis,  and  (4)  tibialis  anticus. 

Talipes  Calcaneo-valgus. — This  is  a  combination  of  talipes  calcaneus  and 
talipes  valgus,  the  foot  being  flexed  and  the  outer  border  of  the  foot  raised. 
The  tendons  involved  are  those  which  are  implicated  in  talipes  calcaneus  and 
talipes  valgus. 

Summary  of  the  Veins  of  the  Lower  Limb. 

The  veins  of  the  lower  limb  are  divided  into  two  groups — superficial  and 
Jeep. 

Superficial  Veins. — In  the  sole  of  the  foot  there  are  (i)  a  plantar  sub- 
cutaneous plexus,  and  (2)  a  transverse  venous  arch  situated  near  the  clefts 
of  the  toes,  which  receives  the  plantar  digital  veins.  The  blood  is  carried 
away  from  the  plantar  subcutaneous  plexus  by  anterior  and  lateral  efferent 
vessels.  The  anterior  efferent  vessels  terminate  in  the  transverse  venous 
arch  near  the  clefts  of  the  toes.  The  lateral  efferent  vessels  turn  round  the 
outer  and  inner  borders  of  the  foot,  the  external  set  terminating  in  the  short 
saphenous  vein,  and  the  internal  set  in  the  long  saphenous  vein,  where  these 
vessels  spring  from  the  dorsal  venous  arch.  The  blood  is  conveyed  away  from 
the  transverse  venous  arch  by  means  of  efferent  veins,  called  interdigital, 
which  pass  upwards  to  the  dorsum  of  the  foot,  where  they  terminate  in  the 
dorsal  venous  arch. 

The  dorsal  venous  arch  is  situated  well  forward  upon  the  dorsum  of  the 
foot,  being  about  2  inches  from  the  webs  of  the  toes.  It  receives  (i)  the 
dorsal  digital  veins,  (2)  small  veins  from  the  dorsum  of  the  foot,  and  (3)  the 
efferent  interdigital  veins  from  the  plantar  transverse  venous  arch.  The 
blood  is  carried  away  from  the  dorsal  venous  arch  by  the  long  and  short  saphe- 
nous veins.  The  long  saphenous  vein  arises  from  the  inner  end  of  the  arch, 
and,  having  received  branches  from  the  plantar  subcutaneous  venous  plexus, 
passes  hi  front  of  the  internal  malleolus,  and  thus  reaches  the  inner  side  of 
the  leg.  Its  subsequent  course  is  upwards  along  the  inner  side  of  the  leg, 
knee,  and  thigh,  and  finally,  having  reached  the  front  of  the  thigh,  it  passes 
through  the  saphenous  opening  li  inches  below  Poupart's  ligament,  and  ter- 
minates in  the  femoral  vein.  It  receives  mariy  tributaries  in  its  course  ; 
in  the  leg  it  communicates  at  frequent  intervals  with  the  vemr  comites  of 
the  anterior  and  posterior  tibial  arteries  by  intermuscular  branches  ;  and 
near  its  termination  it  is  reinforced  by  the  posterior  sa])henous,  anterior 
saphenous,  superficial  circumflex  iliac,  su[)erticial  epigastric,  and  superior 
and  inferior  external  pudic  veins.  The  short  saphenous  vein  arises  from  the 
outer  end  of  the  dorsal  venous  arch,  and,  having  received  branches  from  the 
plantar  subcutaneous  venous  plexus,  it  passes  bdow  and  hchind  the  external 
malleolus,  and  thus  reaches  the  back  of  the  leg.  It  then  ])asses  upwards  and 
inwards,  and  subsequently  straight  upwards  until  it  arrives  at  the  interval 
between  the  condyles  of  the  femur.  Here  it  passes  through  an  aperture  in 
the  fascia  lata,  and  terminates  in  the  popHteal  vein.  It  receives  many 
tributaries  from  the  calcaneal  region  and  the  outer  and  liack  parts  of  the 
leg  ;  it  communicates  at  intervals  with  the  ven;e  comites  of  the  posterior  tiliial 


536  A  MANUAL  OF  ANATOMY 

and  peroneal  arteries  ;  and  near  its   termination  it  communicates  with  the 
long  saphenous  vein.  •**^l 

Deep  Veins. — The  deep  veins  accompany  the  various  arteries  and  their 
branches.  Below  the  level  of  the  popliteus  muscle  they  are  arranged  in  pairs 
along  the  arteries  which  they  accompany,  this  arrangement  being  known  as 
vense  comites.  Opposite  the  lower  border  of  the  popliteus  muscle  the  pos- 
terior tibial  venaj  comites,  having  previously  received  the  peroneal  venae 
comites,  unite  with  the  anterior  tibial  venas  comites,  and  so  the  popliteal  vein 
is  formed,  which  is  continued  into  the  femoral  vein. 

Lymphatic  Vessels. — Lymphatic  vessels  pervade  every  part  of 
the  lower  limb,  and  are  divided  into  a  superficial  and  deep  group. 

Superficial  Group.  —  The  superficial  lymphatics  form  digital, 
plantar,  and  dorsal  plexuses,  and  pass  in  two  sets,  inner  and  outer, 
from  the  respective  parts  of  the  foot.  The  inner  lymphatics  pass 
partly  in  front  of,  and  partly  behind,  the  internal  malleolus,  and, 
following  the  course  of  the  long  saphenous  vein,  terminate  in  the 
superficial  femoral  or  saphenous  glands.  The  outer  lymphatics  pro- 
ceed from  the  outer  part  of  the  foot,  and  most  of  them  pass  in 
front  of  the  external  malleolus,  though  some  pass  behind  it. 
Many  of  them  then  turn  inwards  over  the  front  of  the  leg,  and 
join  the  inner  lymphatics.  Others  continue  their  course  upwards 
along  the  outer  and  back  parts  of  the  leg  and  knee,  and  subsequently 
incline  inwards  to  join  the  inner  set.  A  few,  which  pass  behind  the 
external  malleolus,  accompany  the  short  saphenous  vein  and 
terminate  in  the  popliteal  glands. 

Deep  Group. — ^The  deep  lymphatics  accompany  the  bloodvessels. 
Below  the  level  of  the  knee  they  form  three  sets — anterior  tibial, 
posterior  tibial,  and  peroneal,  all  of  which  terminate  in  the 
popliteal  glands,  the  anterior  tibial  set  having  previously  passed 
through  the  anterior  tibial  gland.  The  efferent  vessels  from  the 
popliteal  glands,  together  with  the  lymphatics  accompanying  the 
branches  of  the  superficial  and  deep  femoral  arteries,  form  the  deep 
lymphatics  of  the  thigh,  and  terminate  in  the  deep  femoral  glands. 

Summary  of  the  Lymphatic  Glands. — The  lymphatic  glands  of  the  lower 
limb  form  the  following  groups  :  (i)  inguinal  (superior  or  oblique  superficial 
inguinal),  (2)  superficial  femoral  or  saphenous  (inferior  or  vertical  superficial 
inguinal),  (3)  deep  femoral  (deep  inguinal),  (4)  popliteal,  and  (5)  anterior 
tibial. 


THE  ANKLE-JOINT. 

The  ankle-joint  belongs  to  the  class  diarthrosis,  and  to  the  sub- 
division ginglymus.  The  articular  surfaces  are  the  lower  extremity 
of  the  shaft  and  the  outer  surface  of  the  internal  malleolus  of  the 
tibia,  the  inner  surface  of  the  external  malleolus  of  the  fibula,  and 
the  superior  and  both  lateral  surfaces  of  the  astragalus.  The 
ligaments  are  anterior,  posterior,  internal  lateral,  and  external 
lateral. 

The  anterior  ligament  is  a  thin  membrane  which  covers  the 
joint   in  front.     Superiorly  it   is   attached   from  within   outwards 


THE  LOWER  LIMB 


537 


to  the  anterior  border  of  the  internal  malleolus,  anterior  surface  of 
the  lower  end  of  the  tibia  two  or  three  lines  above  the  anterior 
border,  anterior  inferior  tibio-fibular  ligament,  and  anterior  border 
of  the  external  malleolus.  Inferiorly  it  is  attached  to  a  groove  on 
the  upper  aspect  of  the  head  of  the  astragalus,  immediately  behind 
the  cartilaginous  surface  and  in  front  of  the  neck.  The  fibres  of  the 
ligament  are  chiefly  disposed  in  a  transverse  direction. 

In  addition  to  the  tendons  which  lie  upon  it,  this  ligament  is 
related  to  the  anterior  tibial  vessels  and  nerve.  Its  deep  surface 
is  covered  by  the  synovial  membrane  of  the  joint,  and  inferiorly  is 
in  contact  with  a  collection  of  fat  which  lies  in  the  hollow  on  the 
upper  surface  of  the  neck  of  the  astragalus. 


_  .Interosseous  Membrane 


Internal  Malleolus  -lU 


Astragalus 

Internal  Lateral  Ligament 

Groove  for  Flexor 
Longus  Hallucis 

Int.  Astragalo-calcaneal 
Ligament 

Tuber  Calcis 


.Posterior  Tibio-fibular 
Ligament 


.External  Malleolus 


Posterior  Band  of  External 
Lateral  Ligament 

Ext.  Astragalo-calcaneal 

Ligament 

Middle  Band  of  External 

Lateral  Ligament 


Fig.  259. — The  Right  Ankle-Joint  (Posterior  View). 
(The  Posterior  Ligament  has  been  removed.) 


The  posterior  ligament  is  weaker  and  less  defined  than  the 
anterior.  Superiorly  it  is  attached  from  without  inwards  to  the 
posterior  aspect  of  the  external  malleolus  internal  to  the  peroneal 
groove,  posterior  inferior  tibio-fibular  ligament,  and  posterior 
border  of  the  tibia  as  far  inwards  as  the  groove  behind  the  internal 
malleolus.  Inferiorly  it  is  attached  to  the  u})per  aspect  of  the 
posterior  border  of  the  astragalus  immediately  behind  the  su])erior 
articular  surface,  where  it  extends  between  the  posterior  fasciculus 
of  the  external  lateral  Hgament  and  the  internal  lateral  ligament. 
Its  fibres  are  disposed  obliquely,  and  radiate  in  an  inward  direction 
from  the  external  malleolus. 


538 


A   MANUAL  OF  ANATOMY 


The   internal   lateral    ligament   is   also   known    as   the    deltoid 

ligament.  It  is  a  strong,  flat,  triangular  structure,  which  is 
attached  superiorly  to  the  lower  border,  tip,  and  anterior  border  of 
the  internal  malleolus,  in  which  latter  situation  it  is  superficial  to 
the  fibres  of  the  anterior  ligament.  A  strong  bundle  of  fibres 
springs  from  the  notch  which  indents  the  lower  border  of  the  internal 
malleolus.  From  the  superior  attachment  the  fibres  diverge  in  a 
radiating  manner.  The  posterior  fibres,  strong  and  short,  descend 
with  an  inclination  backwards  to  be  attached  to  the  rough,  de- 
pressed inner  surface  of  the  astragalus  below  the  internal  facet, 
where  they  extend  as  far  back  as  the  inner  tubercle  on  the  posterior 
border  of  the  bone.  The  anterior  part  of  the  ligament,  somewhat 
thinner   and  more   radiating   than    the   posterior,    is   attached   to 


Internal  Lateral  Ligament 


Posterior  Ligament 
of  Ankle 

Posterior  Astragalo- 
-•  calcaneal  Ligament 


Long  Plantar  Ligament 


Inferior  Calcaneo-navicular  Ligament 

Fig.  260. — Ligaments  of  the  Right  Foot  (Internal  View). 

the  inner  border  of  the  sustentaculum  tali  of  the  os  calcis,  inner 
border  of  the  internal  calcaneo-navicular  or  spring  ligament,  and 
inner  part  of  the  dorsal  surface  of  the  navicular  bone. 

The  external  lateral  ligament  is  composed  of  three  distinct 
fasciculi — anterior,  middle,  and  posterior. 

The  anterior  fascicuhis  {astragalo- fibular)  is  flat,  and  extends  from 
the  lower  part  of  the  anterior  border  of  the  external  malleolus 
to  the  outer  surface  of  the  astragalus  immediately  in  front  of  the 
external  facet.  Its  direction  is  forwards  and  inwards,  and  it  is 
the  shortest  of  the  three  fasciculi. 

The  middle  fasciculus  {calcaneo- fibular) ,  which  is  round,  is  attached 
superiorly  to  the  tip  of  the  external  malleolus,  and  interiorly  to  a 
tubercle  on  the  outer  surface  of  the  os  calcis  situated  about  the 
centre,  behind  and  above  the  peroneal  spine.     Its  direction  is  down- 


THE  LOWER  LIMB 


539 


wards  and  backwards,  and  it  is  related  to  the  tendons  of  the 
peroneus  longus  and  peroneus  brevis. 

The  posterior  fasciculus  {astragalo -fibular)  is  the  strongest  bundle 
of  the  three.  It  is  attached  by  one  extremity  to  the  lower  part  of 
the  digital  fossa  on  the  inner  surface  of  the  external  malleolus 
behind  the  articular  facet.  The  other  extremity  is  attached  to  the 
upper  surface  of  the  outer  tubercle  on  the  posterior  border  of  the 
astragalus.     Its  direction  is  inwards  and  slightly  backwards. 

The  synovial  membrane  lines  the  inner  surfaces  of  the  liga- 
ments in  a  loose  manner,  and  it  covers  collections  of  fat  (Haver- 
sian glands)  at  the  front  and  back  of  the  joint,  where  it  forms  folds 


Posterior  Inferior 
Tibio-fibular  Lig. 


Posterior  Band  of. 
E.xt.  Lat.  Lig. 


Vnterior  Inferior  Tibio-fibular 
Ligament 


Middle  Band  of 
Ext.  Lat.  Lig. 


Peroneus  Longus 


Peroneus  Brevis 


Fig.  261. — Ligaments  of  the  Right  Inferior  Tibio-fibular,  Ankle, 
Tarsal,  and  Tarso-metatarsal  Joints  (External  View). 


which  i^roject  between  the  astragalus  and  the  tibia.  It  is  also 
prolonged  into  the  inferior  tibio-fibular  articulation  so  as  to  line 
the  anterior  and  j)ost(M-ior  ligaments  of  that  joint. 

Tendinous  Relations  of  the  Ankle-Joint  ~/l«/enor.— From  within 
outwards  these  are  the  tibialis  anticus,  extensor  proprius  hallucis, 
extensor  longus  digitorum,  and  j^eronens  tertius.  External. — 
Peroneus  longus  and  jjeroneus  brevis.  Posterior. — From  without 
inwards  these  are  the  i)eroneus  longus  and  peroneus  brevis,  tendo 
Achillis  and  plantaris,  with  the  intervention  of  a  large  amount  of 
fat,  flexor  longus  hallucis,  and  flexor  longus  digitorum  and  tibialis 
I^osticus.     Internal. — ^Tibialis  posticus. 


S40  A  MANUAL  OF  ANATOMY 

Arterial  Supply. — The  anterior  tibial,  external  and  internal 
malleolar,  anterior  peroneal,  posterior  tibial,  and  posterior  peroneal 
arteries. 

Nerve-supply. — The  posterior  tibial,  short  saphenous,  and  external 
division  of  the  dorsalis  pedis  nerve,  or  the  anterior  tibial  nerve 
itself. 

Movements. — The  chief  movements  at  the  ankle-joint  are  flexion  and 
extension.  When,  however,  the  foot  is  extended  a  certain  amount  of  lateral 
movement  is  allowed.  The  foot  is  said  to  be  flexed  when  it  is  raised  from  the 
ground  towards  the  front  of  the  leg,  as  in  standing  upon  the  heels,  and  it 
is  said  to  be  extended  when  the  heel  is  raised  towards  the  back  of  the  leg, 
as  in  standing  upon  the  toes.  In  flexion  of  the  foot  the  broad  anterior 
part  of  the  superior  articular  surface  of  the  astragalus  is  carried  backwards 
into  the  narrow  posterior  part  of  the  tibial  socket,  and  lateral  movement  is  then 
impossible.  Flexion  is  limited  by  (i)  the  tension  of  the  posterior  and  middle 
portions  of  the  internal  lateral  ligament  ;  (2)  the  tension  of  the  posterior  and 
middle  fasciculi  of  the  external  lateral  ligament;  and  (3)  the  locking  which 
takes  place  between  the  upper  surface  of  the  neck  of  the  astragalus  and 
the  anterior  border  of  the  lower  end  of  the  tibia.  In  extension  of  the  foot 
the  narrow  posterior  part  of  the  superior  articular  surface  of  the  astragalus 
is  carried  forwards  into  contact  with  the  broad  anterior  part  of  the  tibial 
socket,  and  a  certain  amount  of  lateral  movement  can  now  take  place.  Exten- 
sion is  limited  by  (i)  the  tension  of  the  anterior  part  of  the  internal  lateral 
ligament  ;  (2)  the  tension  of  the  anterior  and  middle  fasciculi  of  the  external 
lateral  ligament  ;  (3)  the  tension  of  the  anterior  ligament,  particularly  of 
its  inner  part  ;  and  (4)  the  locking  of  the  posterior  part  of  the  astragalus 
against  the  posteror  border  of  the  lower  end  of  the  tibia.  The  range  of 
movement  in  the  direction  of  flexion  and  extension  is  about  90  degrees, 
and  it  takes  place  round  a  transverse  axis  passing  through  the  body  of  the 
astragalus  in  a  direction  forwards  and  outwards.  At  the  end  of  extension 
there  is  a  tendency  to  abduction  or  turning  in  of  the  foot,  due  to  the  following 
factors  :  (i)  the  greater  length  posteriorly  of  the  inner  border  of  the  superior 
articular  surface  of  the  astragalus  ;  (2)  the  greater  depression  of  the  corre- 
sponding part  of  the  outer  border  of  the  astragalus  ;  and  (3)  adduction  at 
the  astragalo-calcaneal  joint. 

The  vertical  line  of  the  centre  of  gravity  falls  in  front  of  the  axis  of  move- 
ment at  the  ankle-joint.  There  is  thus  a  tendency  to  over-flexion,  which, 
however,  is  counteracted  by  a  certain  amount  of  muscular  effort  on  the  part 
of  the  sural  muscles. 

Muscles  concerned  in  the  Movements — Flexion. — This  is  produced  by  the 
tibialis  anticus,  peroneus  tertius,  extensor  longus  digitorum,  and  extensor 
proprius  hallucis. 

Extension. — This  is  produced  by  the  gastrocnemius  and  soleus  by  means 
of  the  tendo  Achillis,  plantaris,  tibialis  posticus,  flexor  longus  digitorum, 
flexor  longus  hallucis,  peroneus  longus,  and  peroneus  brevis. 

Abduction. — The  foot  is  everted  by  the  peroneus  longus  and  peroneus 
brevis. 

Adduction. — The  foot  is  inverted  by  the  tibialis  anticus  and  tibialis  posticus. 


THE  TIBIO-FIBULAR  JOINTS. 

The  superior  and  inferior  extremities  of  the  tibia  and  fibula  form 
direct  articulations,  and  the  shafts  are  connected  by  means  of  an 
interosseous  membrane. 

Superior  Tibio-fibular  Joint.— This  joint  belongs  to  the  class 
diarthrosis,  and  to  the  subdivision  arthrodia.     The  articular  sur- 


THE  LOWER  LIMB  541 

faces  are  the  facets  on  the  head  of  the  fibula  and  on  the  external 
tuberosity  of  the  tibia,  and  the  ligaments  are  two  in  number, 
namely,  anterior  and  posterior.  Their  fibres  pass  downwards  and 
outwards  from  the  outer  tuberosity  of  the  tibia  to  the  head  of  the 
fibula,  and  they  completely  cover  the  joint  in  front  and  behind. 
Superiorly  and  interiorly  they  meet,  and  thus  construct  a  capsule 
for  the  joint.  The  anterior  division  of  the  tendon  of  the  biceps 
femoris  is  closely  related  to  the  anterior  ligament,  and  contributes 
materially  to  the  strength  of  the  joint,  the  more  so  because  that 
division  has  an  insertion  into  the  outer  tuberosity  of  the  tibia  as 
well  as  into  the  upper  surface  of  the  head  of  the  fibula. 

The  synovial  membrane  is  usually  distinct  from  that  of  the  knee- 
joint.  Occasionally,  however,  it  is  in  communication  with  it 
posteriorly  by  means  of  the  synovial  investment  which  surrounds 
the  tendon  of  the  popliteus. 

Arterial  Supply. — The  arterial  supply  is  derived  from  the  inferior 
external  articular,  posterior  tibial  recurrent  (inconstant),  and  anterior 
tibial  recurrent  arteries. 

Nerve-supply. — The  inferior  external  articular  and  recurrent 
articular,  both  branches  of  the  external  popliteal,  and  the  nerve  to 
the  popliteus  muscle,  which  is  a  branch  of  the  internal  popliteal. 

Movements. — The  movements  are  extremely  limited,  and  are  of  a  gliding 
or  to-and-fro  nature  in  an  upward  and  downward  direction.  The  knee  being 
almost  fully  extended,  if  the  fingers  are  placed  over  the  head  of  the  fibula 
whilst  the  foot  is  alternately  flexed  and  extended,  the  head  of  the  bone  will 
be  felt  to  glide  upwards  during  flexion  and  downwards  during  extension  of 
the  foot. 

Inferior  Tibio  -  fibular  Joint. — This  joint  belongs  to  the  class 
diarthrosis,  and  to  the  subdivision  arthrodia.  The  articular  sur- 
faces are  the  upper  part  of  the  facet  on  the  inner  surface  of  the 
external  malleolus  of  the  fibula  and  the  facet  on  the  outer  aspect 
of  the  lower  end  of  the  tibia.  The  ligaments  are  anterior,  posterior, 
inferior  interosseous,  and  transverse. 

The  anterior  ligament  is  a  strong,  flat  band,  the  fibres  of  which 
pass  obliquely  downwards  and  outwards  from  the  tibia  to  the  fibula. 
It  is  related  anteriorly  to  the  peroneus  tertius,  and  posteriorly  is 
in  contact  with  the  inferior  interosseous  ligament. 

The  posterior  ligament,  which  is  disposed  like  the  anterior,  is 
in  contact  with  the  transverse  ligament  interiorly,  and  with  the 
inferior  interosseous  ligament  anteriorly. 

The  inferior  interosseous  ligament  is  an  important  ligament, 
and  is  of  considerable  strength.  It  consists  of  short  fibres  which 
pass  directly  between  the  o])j)osed  rough  triangular  surfaces  at  the 
lower  ends  of  the  shafts  of  the  tibia  and  fibula.  It  is  continuous 
above  with  the  interosseous  membrane,  and  its  extent  is  about 
1 1  inches.  Anteriorly  and  jxjsteriorly  it  is  in  part  related  to  the 
anterior  and  j)Osterior  inferior  tibio-fibular  ligaments.  The  ])art 
of  the  inferior   tibio-fibular  joint  occupied   by   the   inferior   inter- 


542  A  MANUAL  OF  ANATOMY 

osseous  ligament  belongs  to  the  class  amphiarthrosis,  and  to  the 
subdivision  syndesmosis. 

The  transverse  ligament,  which  is  strong,  narrow,  and  somewhat 
round,  extends  almost  horizontally  from  the  posterior  border  of 
the  lower  end  of  the  tibia  to  the  upper  part  of  the  digital  fossa 
of  the  external  malleolus.  Externally  it  lies  along  the  lower  border 
of  the  posterior  inferior  tibio-fibular  ligament,  by  which  it  is 
shghtly  overlapped.  It  fills  up  a  slight  hollow  between  the  tibia 
and  fibula,  and  it  plays  across  the  back  part  of  the  upper  articular 
surface  of  the  astragalus,  where  it  usually  gives  rise  to  a  transverse 
groove.  The  transverse  ligament  completes  the  back  part  of  the 
tibial  socket  for  the  upper  surface  of  the  astragalus. 

The  synovial  membrane  is  continuous  with  that  of  the  ankle- 
joint. 

Arterial  Supply. — The  posterior  and  anterior  peroneal  arteries, 
and  the  external  malleolar  of  the  anterior  tibial. 

Nerve-supply. — The  interosseous  branch  of  the  nerve  to  the  pop- 
liteus  muscle,  and  the  external  division  of  the  dorsalis  pedis  nerve. 

Movements. — These  are  very  limited,  and  are  of  a  gliding  nature,  chiefly 
upwards  and  downwards,  the  fibula  moving  on  the  tibia.  Though  the  bones 
are  firmly  bound  together  by  the  inferior  interosseous  ligament,  there  is  yet  a 
certain  amount  of  lateral  separation  allowed  during  flexion  of  the  foot. 

Intermediate  Connection  between  the  Tibia  and  Fibula.  —  The 

union  between  the  shafts  of  the  tibia  and  fibula  is  effected  by 
means  of  an  interosseous  membrane.  This  kind  of  union  is  a  form 
of  syndesmosis  (union  by  an  interosseous  ligament).  The  inter- 
osseous membrane  extends  from  the  external  border  or  interosseous 
ridge  of  the  tibia  to  the  antero-internal  border  or  interosseous  ridge 
of  the  fibula.  The  chief  direction  of  the  fibres  is  downwards  and 
outwards  from  the  tibia  to  the  fibula,  but  a  few  pass  in  the  opposite 
direction.  Superiorly  it  terminates  about  i  inch  below  the  superior 
tibio-fibular  joint  in  a  sharp  concave  margin,  the  concavity  of 
which  is  directed  upwards.  An  interval  is  thus  left  above  the 
membrane  for  the  passage  of  the  anterior  tibial  vessels  and  the 
efferent  lymphatics  of  the  anterior  tibial  gland.  Sometimes  these 
structures  pass  through  a  distinct  aperture  in  the  membrane,  called 
the  superior  hiatus.  Interiorly  it  becomes  continuous  with  the 
inferior  interosseous  ligament,  and  in  this  neighbourhood  it  presents 
a  small  opening  or  inferior  hiatus  for  the  passage  of  the  anterioi 
peroneal  vessels.  The  interosseous  membrane  serves  as  a  surface  of 
origin  to  muscles. 

Relations — Anterior. — ^Tibialis  anticus,  over  the  upper  two-thirds 
of  the  inner  half  ;  extensor  longus  digitorum,  over  the  upper  fourth 
of  the  outer  half  ;  extensor  proprius  hallucis,  over  the  middle  two- 
fourths  of  the  outer  half  ;  peroneus  tertius,  over  the  lower  fourth 
of  the  outer  half  ;  anterior  tibial  vessels,  over  the  upper  two-thirds 
in  the  middle  line  ;  and  anterior  tibial  nerve,  over  the  middle  third. 
Posterior. — ^Tibialis  posticus. 


THE  LOWER  LIMB 


543 


Arterial  Supply. — The  anterioi"  tibial  and  peroneal  arteries. 

Nerve-supply. — The  interosseous  branch  of  the  nerve  to  the  pop- 
liteus  muscle,  which  descends  within  it  to  terminate  in  the  inferior 
tibio-fibular  joint. 

THE  ARCHES  OF  THE  FOOT. 

The  foot  presents  two  arches — antero-posterior  or  longitudinal 
and  transverse. 

Antero-posterior  or  Longitudinal  Arch.  —  The  posterior  pier  of 
this  arch  is  formed  by  the  plantar  aspect  of  the  tuber  calcis,  and 
the  anterior  pier  by  the  heads  of  the  metatarsal  bones.  The  arch 
is  single  behind,  where  it  is  formed  by  the  posterior  two-thirds  of 
the  OS  calcis,  but  it  is  divided  into  two  pillars  in  front.  The  internal 
pillar  is  formed  by  the  astragalus,  navicular,  all  three  cuneiforms, 
and  the  inner  three  metatarsal  bones.  It  is  more  raised  from  the 
ground,  and  has  to  bear  more  weight,  than  the  external.  The 
external  pillar  is  formed  by  the  anterior  third  of  the  os  calcis,  cuboid, 
and  outer  two  metatarsal  bones,  and  is  nearer  the  ground  than  the 
internal.  There  is  a  natural  tendency  in  the  erect  posture  to 
flattening  of  the  antero-posterior  arch,  but  this  is  guarded  against 
by  (i)  the  inferior  or  internal  calcaneo-navicular  or  spring  ligament, 

(2)  the  calcaneo-cuboid  ligaments  (long  and  short  plantar  ligaments), 

(3)  the  central  division  of  the  plantar  fascia,  and  (4)  the  tendon  of 
the  tibialis  posticus,  with  its  various  expansions. 

Transverse  Arch. — This  arch  is  best  marked  at  the  tarso-meta- 
tarsal  articulations,  and  is  due  to  the  broad  aspects  of  the  middle 
and  external  cuneiform  bones  being  dorsally  placed,  and  the  broad 
aspects  of  the  wedge-shaped  bases  of  the  second,  third,  and  fourth 
metatarsal  bones  being  also  dorsally  placed.  There  is  a  tendency 
to  flattening  of  the  transverse  arch  when  a  person  stands  upon 
the  toes,  but  the  arch  is  maintained  by  the  plantar  and  interosseous 
ligaments. 

THE  ARTICULATIONS  OF  THE  FOOT. 

The  articulations  of  the  foot  are  divided  into  tarsal,  tarso-meta- 
tarsal,  intermetatarsal,  metatarso-phalangeal,  and  interphalangeal. 

The  Tarsal  Articulations. 

I.  Astragalo-calcaneal  Joints. — The  astragalus  is  connected  with 
the  OS  calcis  Ijy  two  synovial  joints,  anterior  and  posterior,  both 
of  which  belong  to  the  class  diarthrosis,  and  to  the  subdivision 
arthrodia. 

Posterior  Astragalo-calcaneal  Joint. — The  ligaments  are  inter- 
osseous, posterior,  internal,  and  external. 

The  interosseous  ligament  jjasses  between  the  obhqnc  grooves 
separating  the  two  articular  surfaces  of  each  l)one,  and  lorming 


544  A  MANUAL  OF  ANATOMY 

by  their  apposition  the  tunnel  called  the  sinus  pedis.  It  is  very 
strong,  and  is  to  be  regarded  as  the  anterior  ligament  of  the  posterior 
astragalo-calcaneal  joint. 

The  posterior  ligament  extends  from  the  posterior  aspect  of  the 
outer  tubercle  on  the  posterior  border  of  the  astragalus  to  the 
adjacent  upper  and  inner  surfaces  of  the  os  calcis.  It  is  thin  and 
membranous,  and  its  fibres  are  arranged  in  a  radiating  manner. 

The  internal  ligament  is  a  narrow  band  which  passes  from  the 
inner  tubercle  on  the  posterior  border  of  the  astragalus  to  the  back 
of  the  sustentaculum  tali  of  the  os  calcis.  It  is  related  to  the 
tendon  of  the  flexor  longus  hallucis. 

The  external  ligament  extends  from  the  lower  part  of  the  outer 
surface  of  the  astragalus,  below  the  facet,  to  be  attached  to  the 
adjacent  part  of  the  outer  surface  of  the  os  calcis.  It  is  under 
cover  of,  and  parallel  with,  the  middle  fasciculus  of  the  external 
lateral  ligament,  which,  along  with  the  internal  lateral  ligament  of 
the  ankle-joint,  contributes  to  the  strength  of  this  articulation. 

The  synovial  membrane  of  this  joint  is  peculiar  to  it. 

Arterial  Supply. — The  arterial  supply  is  derived  from  the  posterior 
tibial,  external  malleolar  of  the  anterior  tibial,  posterior  peroneal, 
and  external  tarsal  of  the  dorsalis  pedis  artery. 

Nerve-supply. — The  short  saphenous  and  the  posterior  tibial,  or 
it  may  be  the  external  plantar,  nerves. 

Anterior  Astragalo-calcaneal  Joint. — ^This  joint  has  a  lateral  liga- 
ment at  either  side,  and  a  posterior,  but  it  is  continuous  anteriorly 
with  the  astragalo-navicular  joint.  The  ligaments  are  interosseous 
or  posterior,  internal  astragalo-calcaneal,  and  external  or  superior 
calcaneo-navicular. 

The  interosseous  or  posterior  ligament  has  already  been  described 
in  connection  with  the  posterior  astragalo-calcaneal  joint. 

The  internal  astragalo-calcaneal  ligament  extends  from  the 
inner  surface  of  the  neck  of  the  astragalus  to  the  upper  margin 
of  the  inner  border  of  the  sustentaculum  tali  of  the  os  calcis. 
It  blends  posteriorly  with  the  inner  end  of  the  interosseous 
ligament,  and  anteriorly  with  the  upper  border  of  the  internal 
calcaneo-navicular  or  spring  ligament.  It  is  strengthened  by  the 
internal  lateral  ligament  of  the  ankle-joint.  The  internal  or  inferior 
calcaneo-navicular  or  spring  ligament  is  also  an  internal  ligament 
of  this  joint,  but,  inasmuch  as  it  ranks  as  a  ligament  of  the  astra- 
galo-navicular joint,  it  will  be  described  in  connection  with  that 
articulation. 

The  external  or  superior  calcaneo-navicular  ligament  is  placed  on 
the  outer  side  of  the  joint.  It  also  ranks  as  an  external  lateral 
ligament  of  the  astragalo-navicular  joint.  It  is  strong,  and  extends 
from  the  anterior  part  of  the  upper  surface  of  the  os  calcis,  external 
to  the  anterior  facet,  to  a  depression  on  the  outer  surface  of  the 
navicular  bone  near  its  posterior  margin.  Inferiorly  it  blends  with 
the  internal  calcaneo-navicular  ligament,  and  superiorly  with  the 
superior  astragalo-navicular  ligament. 


THE  LOWER  LIMB  545 

The  synovial  membrane,  though  distinct  from  that  of  the  posterior 
astragalo-calcaneal  joint,  is  continuous  in  front  with  that  of  the 
astragalo-navicular  articulation. 

The  arterial  supply  and  nerve-supply  arc  the  same  as  for  the 
astragalo-navicular  articulation. 

Movements  between  the  Astragalus  and  Os  Calcis. — The  movements  at  the 
astragalo-calcaneal  joints  are  abduction,  adduction,  and  rotation.  In 
abduction  the  foot  and  toes  are  turned  outwards,  and  in  adduction  they  are 
turned  inwards,  these  movements  being  associated  with  a  certain  amount  of 
rotation  round  an  axis  passing  from  the  inner  side  of  the  neck  of  the  astra- 
galus downwards,  backwards,  and  outwards  to  the  lower  and  outer  part  of 
the  tuber  calcis.  In  adduction  or  inversion  the  posterior  facet-  of  the  os 
calcis  moves  forwards  and  downwards  upon  the  astragalus,  and  the  front 
part  of  the  os  calcis  is  carried  slightly  inwards.  During  the  movements 
the  navicular  bone  rotates  on  the  head  of  the  astragalus,  and  the  cuboid 
bone  moves  along  with  the  os  calcis. 

II.  Astragalo-navicular  Joint. — This  belongs  to  the  class 
diarthrosis,  and  to  the  subdivision  enarthrosis.  It  is  in  direct 
continuity  behind  with  the  anterior  astragalo-calcaneal  joint,  with 
which  it  shares  its  synovial  membrane,  and  the  two  articulations 
are  sometimes  described  as  one  composite  joint  under  the  name  of 
the  astragalo-calcaneo-navicular  joint.  The  ligaments  are  astragalo- 
navicular,  external  or  superior  calcaneo-navicular,  and  internal  or 
inferior  calcaneo-navicular,  or  spring,  ligament. 

The  astragalo-navicular  ligament  is  a  thin  membrane  which 
covers  the  joint  on  its  dorsal  aspect.  It  is  attached  posteriorly 
to  the  upper  margin  of  the  head  of  the  astragalus  close  behind  the 
cartilage,  and  also  to  its  outer  and  inner  surfaces.  Anteriorly  it 
is  attached  to  the  dorsal  surface  of  the  navicular  bone.  Its  fibres  are 
arranged  in  a  radiating  manner,  and  converge  towards  the  navicular 
bone.  At  the  attachment  to  the  astragalus  they  frequently  form 
three  bands,  outer,  dorsal,  and  inner,  which,  however,  are  continuous 
with  one  another. 

The  external  or  superior  calcaneo-navicular  ligament  has  been 
described  in  connection  with  the  anterior  astragalo-calcaneal  joint, 
of  which  it  ranks  as  the  external  ligament. 

The  internal  or  inferior  calcaneo-navicular  ligament  is  one 
of  the  most  important  ligaments  of  the  foot,  and  is  known  as 
the  spring  ligament.  It  is  a  broad,  thick,  strong  band  of  the 
consistence  of  fibro-cartilage,  and  is  com]:)osed  of  fibrous  and  elastic 
tissues.  Posteriorly  it  is  attached  to  the  front  of  the  sustentaculum 
tali  and  the  adjacent  portion  of  the  i:)lantar  surface  of  the  os  calcis. 
Anteriorly  it  is  attached  to  (i)  the  plantar  surface  of  the  navicular 
bone,  (2)  the  back  of  its  tuberosity,  and  (3)  the  inner  ])art  of  its 
dorsal  surface.  It  is  directed  forwards  and  inwards,  and  covers 
the  joint  on  its  inner  and  lower  aspects.  Internally  it  blends 
with  the  anterior  part  of  the  internal  lateral  ligament  of  the 
ankle-joint  and  the  astragalo-navicular  ligament,  and  externally 
it  blends  with  the  external  calcaneo-navicular  ligament.  The 
superior  or  deep  surface  of  the  ligament  is  in  contact  with  a  special 

.35 


546 


A   MANUAL  OF  ANATOMY 


facet  on  the  internal  aspect  of  the  inferior  surface  of  the  head 
of  the  astragalus.  This  surface  of  the  ligament  is  covered  by 
synovial  membrane,  and  forms  part  of  the  articular  socket  for 
the  head  of  the  astragalus.  It  has  a  smooth,  polished  appearance, 
and  presents  no  indication  of  its  fibrous  structure.  The  inferior 
or  superficial  surface,  on  the  other  hand,  has  the  ordinary  fibrous 
appearance  of  a  ligament,  and  is  in  close  contact  with  the  tendon 
of  the  tibialis  posticus,  which  is  a  powerful  auxiliary  to  the  ligament 
in  supporting  the  antero-posterior  arch  of  the  foot.  The  spring 
ligament  sometimes  contains  a  sesamoid  fibro-cartilage,  which 
occasionally  becomes  ossified. 


External  Calcaneo-navicular 

Ligament  yi^lS^ 


Facet  for  Spring  Ligament 


Tendon  of  Tibialis  Posticus 

'Inferior  Calcaneo-navicular  or 
Spring  Ligament 

Interosseous  Ligament 


Fig.  262. — The  Inferior  Calcaneo-navicular  or  Spring  Ligament 
OF  THE  Left  Foot  (Superior  View). 


The  astragalo-navicular,  external  or  superior  calcaneo-navicular, 
and  internal  or  inferior  calcaneo-navicular  ligaments  form  together 
a  capsule  for  the  astragalo-navicular  joint. 

The  synovial  membrane  is  continuous  with  the  synovial  mem- 
brane of  the  anterior  astragalo-calcaneal  joint. 

Arterial  Supply. — ^The  anterior  tibial,  external  tarsal  branch  of 
the  dorsalis  pedis,  and  internal  plantar  arteries. 

Nerve-supply. — ^The  internal  plantar  and  the  external  division 
of  the  dorsalis  pedis  nerve. 

The  movements  at  this  joint  will  be  described  with  those  at  the 
calcaneo-cuboid  joint. 


THE  LOWER  LIMB 


$A7 


III.  Calcaneo-cuboid  Joint. — This  belongs  to  the  class  diar- 
throsis,  and  to  the  subdivision  reciprocal  or  saddle-joint.  The  liga- 
ments are  dorsal,  internal  or  interosseous,  long  plantar,  and  short 
plantar. 

The  dorsal  ligament  is  a  broad,  flat  band  which  passes  between 
the  superior  surfaces  of  the  os  calcis  and  cuboid. 

The  internal  or  interosseous  ligament  is  a  strong  band  which 
lies  deeply  in  the  hollow  between  the  fore  parts  of  the  astragalus 
and  OS  calcis,  where  it  is  connected  with  the  external  calcaneo- 
navicular ligament.  Its  attachments  are  to  the  adjacent  inner 
portions  of  the  os  calcis  and  cuboid. 

The  long  plantar  (long  inferior  calcaneo-cuboid)  ligament  is  very 
strong,  and  is  attached  posteriorly  to  the  plantar  surface  of  the  os 
calcis,  upon  which  it  extends  from  the  inner  and  outer  tubercles 
to  the  anterior  tubercle.  Anteriorly  most  of  its  fibres  are  attached 
to  the  ridge  on  the  plantar  surface  of  the  cuboid  bone  behind  the 
peroneal  groove.  Some  of  them,  however,  are  continued  forwards  to 
be  attached  to  the  plantar  aspects  of  the  bases  of  the  second,  third, 
fourth,  and  fifth  metatarsal  bones.  These  latter  fibres,  as  they 
pass  over  the  peroneal  groove,  cover  the  tendon  of  the  peroneus 
longus,  and  so  complete  its  fibro-osseous  canal. 

The  short  plantar  (short  inferior  calcaneo-cuboid)  ligament  is  more 
deeply  placed  than  the  preceding.  Posteriorly  it  is  attached  to  the 
plantar  surface  of  the  os  calcis  in  front  of  the  anterior  tubercle,  as 
well  as  to  the  fore  part  of  that  tubercle,  and  anteriorly  to  the 
plantar  surface  of  the  cuboid  bone  behind  the  ridge. 

The  long  and  short  plantar  Ugaments  are  in  early  life  continuous  with 
the  tendo  Acliillis,  but  they  become  subsequently  separated  from  it  as  the 
result  of  the  backward  growth  of  the  heel. 

The  synovial  membrane  of  this  joint  is  peculiar  to  it. 

Arterial  Supply. — The  external  tarsal  branch  of  the  dorsalis  pedis 
and  the  external  plantar  artery. 

Nerve-supply. — The  external  plantar  and  the  external  division  of 
the  dorsalis  pedis  nerve. 

Movements  at  the  Astragalo-navicular  and  Calcaneo-cuboid  Joints.-  The 

movements  at  these  joints  are  flexion  and  extension,  combined  with  abduction, 
adduction,  and  rotation.  Flexion  occurs  during  extension  of  the  ankle-joint, 
and  extension  during  flexion  of  that  joint.  The  axis  of  tliese  movements 
passes  from  tlie  inner  side  of  the  neck  of  the  astragalus  obliquely  down- 
wards, outwards,  and  l)ackwar(ls  to  the  lower  and  outer  part  of  tlie  tul)er 
calcis.  During  flexion  and  extension  of  the  astragalo-navicidar  joint  rota- 
tion of  the  navicular  bone  on  tlie  head  of  tlu;  astragalus  takes  place.  The 
most  free  movement  at  this  joint  is  downwards  and  inwards,  or  upwards 
and  outwards.  In  adduction  and  abduction  of  the  foot  movement  take;. 
place  at  this  joint  as  well  as  at  the  astragalo-calcaneal  articulations.  In 
adduction  or  inversion  the  navicular  bone  moves  downwards  and  inwards, 
and  so  also  does  the  cuboid  at  the  calcaneo-cuboid  joint,  the  result  being 
that  the  antero-posterior  arch  of  the  foot  is  diminished.  In  abduction  or 
aversion  the  navicular  and  cuboid  bones  move  u|)wards  and  outwards,  and 
the  antero-posterior  arch  is  increased. 

In  walking  the  head  of  the  astragalus  tends  to  sink  upon  the  spring  ligament, 

35—2 


548 


A   MANUAL  OF  ANATOMY 


and  a  certain  amount  of  abduction  or  eversion  of  the  foot  takes  place.  When 
a  person  stands  erect  with  both  feet  upon  the  ground,  abduction  or  eversion 
is  prevented  by  the  astragalo-calcaneal  hgaments.  If,  however,  the  spring 
ligament  is  in  a  weak  condition,  the  tendon  of  the  tibialis  posticus  is  not  of 
itself  sufficient  to  prevent  displacement  of  the  head  of  the  astragalus  down- 
wards and  inwards.  Displacement  accordingly  takes  place  in  that  direction, 
and  so  the  condition  known  as  flat  foot  (pes  planus)  is  produced. 

At  the  calcaneo-cuboid  joint,  besides  the  movements  of  flexion  and  exten- 
sion combined  with  adduction  and  abduction,  movement  takes  place  down- 
wards and  inwards,  or  upwards  and  outwards.     The  astragalo-navicular  and 


Tuber  Calcis 


Groove  for  Flexor  Lon; 
Hallucis 


Sustentaculum  Tali 


External  Calcaneo- 
navicular Ligament 


Tibialis  Posticus 

Inferior  Calcanec-. 
navicular  (Spring) 
Ligament 
Short  Plantar  Ligament 

Naviculo-cuboid  Ligament 
Navicular  Bone 


Naviculo-cuneiform  / 
Ligaments       ^^ 


Internal  Cuneiform 
Bone 


Insertion  of  Peroneus 

Longus 
Capsule  of  ist  Tarso- 
metatarsal Joint 


Long  Plantar  Ligament 


eroneus  Longus 
Peroneus  Brevis 


Cubo-metatarsal 
Ligament 


Fig.   263. — Ligaments  of  the  Right  Foot  (Plantar  Aspect). 


calcaneo-cuboid  joints  together  constitute  the  transverse  tarsal  articulation, 
the  direction  of  which  is  in  a  straight  line  across  the  foot.  It  is  at  this  trans- 
verse tarsal  joint  where  disarticulation  is  performed  in  Chopart's  operation. 

IV.  Naviculo-cuboid  Joint. — This  belongs  to  the  class  diarthrosis, 

and  to  the  subdivision  arthrodia,  but  only  in  those  cases  where  the 
two  bones  articulate  directly  with  each  other  by  faceted  surfaces. 
The  ligaments  are  dorsal,  plantar,  and  interosseous. 

The  dorsal  ligament  passes  from  the  outer  part  of  the  dorsal 


THE  LOWER  LIMB 


549 


surface  of  the  navicular  bone  to  the  middle  third  of  the  inner  border 
of  the  dorsal  surface  of  the  cuboid. 

The  plantar  ligament  is  a  strong  band  which  extends  from  the 
outer  part  of  the  plantar  surface  of  the  navicular  bone  to  the  internal 
part  of  the  plantar  surface  of  the  cuboid.  Its  direction  is  forwards 
and  outwards. 

The  interosseous  ligament  is  also  a  strong  band  which  extends 
between  the  contiguous  surfaces  of  the  two  bones.  The  navicular 
and  cuboid  bones  do  not,  as  a  rule,  articulate  directly  with 
each  other  by  cartilaginous  surfaces,  and  under  these  circum- 
stances there  is  no  synovial  membrane  at  this  joint.  Sometimes, 
however,  the  two  bones  come  into  actual  contact,  and  then  each  has 
a  special  articular  facet,  that  on  the  navicular  bone  being  situated 
on  its  outer  extremity,  adjacent  to  the  facet  for  the  external  cunei- 
form, and  that  on  the  cuboid  being  situated  on  its  internal  surface, 
behind  the  normal  facet  for  the  external  cuneiform.  When  the 
two  bones  are  thus  in  actual  contact  the  joint  is  provided  with  a 
synovial  membrane  which  is  continuous  with  that  of  the  naviculo- 
cuneiform  articulation. 

V.  Naviculo-cuneiform  Joint. — This  belongs  to  the  class  diar- 
throsis,  and  to  the  subdivision  arthrodia.  The  ligaments  are  dorsal, 
plantar,  and  internal. 

The  dorsal  ligament  is  a  strong,  continuous  sheet  of  fibres  passing 
from  the  dorsal  surface  of  the  navicular  bone  to  the  dorsal  surfaces 
of  the  three  cuneiform  bones. 

The  plantar  ligament  extends  between  the  plantar  surface  of  the 
navicular  bone  and  the  }:)lantar  surfaces  of  the  three  cuneiform 
bones.  To  a  large  extent  it  derives  its  fibres  from  the  adjacent 
expansions  of  the  tendon  of  the  tibialis  posticus. 

The  internal  ligament  j)asses  between  the  tuberosity  of  the  navi- 
cular bone  and  the  inner  surface  of  the  internal  cuneiform,  and  it 
blends  with  the  dorsal  and  plantar  ligaments. 

VI.  Intercuneiform  Joints. — These  belong  to  the  class  diarthrosis, 
and  to  the  subdivision  arthrodia.  The  ligaments  are  dorsal,  inter- 
osseous, and  ])lantar. 

The  dorsal  ligaments  are  two  in  number,  and  their  fibres  })ass 
transversely  between  the  dorsal  aspect  of  the  middle  cuneiform  and 
the  dorsal  asjjccts  of  th(!  internal  and  external  cuneiform  l)ones. 

The  interosseous  ligaments  are  also  two  in  number,  and 
are  very  strong.  They  are  deeply  j)]aced,  and  pass  between  the 
sides  of  the  middle  cuneiform  and  the  contiguous  sides  of  the 
internal  and  external  cuneiform  bones  in  front  of  the  articular 
facets.  They  constitute  the  chief  bond  of  union  between  the  three 
bones. 

The  ligament  between  the  middle  and  external  cuneiform  is 
attached  to  the  entire  vertical  extent  of  the  contiguous  surfaces, 
whilst  that  between  the  mifldlc  and  internal  cuneiform  is  generally 
limited  to  the  inferior  and  anterior  jjortions  of  the  contiguous 
surfaces. 


S50 


A  MANUAL  OF  ANATOMY 


The  plantar  ligament  passes  between  the  inner  aspect  of  the 
eminence  on  the  plantar  surface  of  the  internal  cuneiform  and  the 
plantar  aspect  of  the  middle  cuneiform. 

VII.  Cubo-cuneiform  Joint. — ^This  belongs  to  the  class  diarthrosis, 
and  to  the  subdivision  arthrodia.  The  ligaments  are  dorsal,  plantar, 
and  interosseous. 

The  dorsal  ligament  passes  between  the  dorsal  surface  of  the 
external  cuneiform  bone  and  the  dorsal  surface  of  the  cuboid. 

The  plantar  ligament  passes  from  the  plantar  aspect  of  the 
external  cuneiform  bone  to  the  internal  surface  of  the  cuboid  over 
its  anterior  half,  close  to  the  plantar  surface. 

The  interosseous  ligament,  which  is  strong  and  deeply  placed, 
passes  between  the  entire  vertical  extent  of  the  contiguous  surfaces 
of  the  two  bones  in  front  of  the  articular  facets. 

Synovial  Membrane  of  the  Navieulo-cuneiform,  Intercuneiform, 
and  Cubo-cuneiform  Joints. — ^The  navieulo-cuneiform  synovial  mem- 
brane is  usually  prolonged  into  the  cubo-cuneiform  joint,  though 


Interosseous  Ligament 


•VU:;-!,  M. 


2.M. 


3.M. 


4.M. 


5.M. 


Fig.  264. 


-The  Synovial  Cavities  of  the  Iarsal  and 
Tarso-metatarsal  Joints. 


occasionally  the  latter  has  a  synovial  sac  peculiar  to  it.  It  is  also 
continued  into  the  naviculo-cuboid  joint  in  those  cases  where  these 
two  bones  articulate  by  facets.  Further,  it  sends  forwards  two 
prolongations,  one  on  either  side  of  the  middle  cuneiform.  The 
prolongation  between  the  middle  and  external  cuneiform  and  that 
between  the  external  cuneiform  and  cuboid  are  entirely  shut  off 
from  the  synovial  cavity  of  the  middle  tarso-metatarsal  joint  (the 
joint  between  the  cuneiform  bones  and  the  second  and  third  meta- 
tarsal bones).  The  explanation  of  this  is  that  the  interosseous 
ligaments  between  the  middle  and  external  cuneiform  and  between 
the  external  cuneiform  and  cuboid,  which  are  placed  in  front  of  the 
articular  surfaces,  are  attached  over  the  entire  vertical  extent  of 
the  contiguous  surfaces  from  the  dorsal  ligaments  above  to  the 
plantar  below.     The  prolongation,  however,  between  the  middle 


THE  LOWER  LIMB  551 

and  internal  cuneiform  is  usually  continuous  in  front  with  the 
synovial  membrane  of  the  middle  tarso-metatarsal  joint,  because  the 
interosseous  ligament  between  these  two  bones  is  generally  limited 
to  the  inferior  and  anterior  portions  of  the  contiguous  surfaces.  If 
this  ligament  should  reach  the  dorsal  surface,  the  naviculo-cuneiform 
synovial  membrane  would  be  entirely  isolated  from  that  of  the  middle 
tarso-metatarsal  joint. 

Arterial  Supply. — The  arterial  supply  of  the  naviculo-cuboid, 
naviculo-cuneiform,  intercuneiform,  and  cubo-cuneiform  joints  is 
derived  from  the  metatarsal  branch  of  the  dorsalis  pedis  and  the 
internal  and  external  plantar  arteries. 

Nerve-supply.— The  dorsalis  pedis,  internal  plantar,  and  external 
plantar  nerves. 

Movements  at  the  Naviculo-cuneiform,  Intercuneiform,  and  Cubo-cuneiform 
Joints. — The  movements  at  these  joints  are  very  limited,  and  are  of  the  gliding 
or  to-and-fro  variety.  They  do  not  affect  the  position  of  the  foot  as  regards 
liexion  and  extension,  or  inversion  and  eversion,  but  they  influence  the 
transverse  arch  by  increasing  or  diminisliing  its  span.  Downward  gliding 
would  increase  the  span,  and  upwanl  gliding  would  diminish  it. 

The  portion  of  the  transverse  arch  which  is  formed  by  the  three  cuneiform 
and  cuboid  bones  has  the  following  muscles  attached  to  its  variousparts — tibialis 
posticus,  flexor  brevis  hallucis,  adductor  obliquus  hallucis,  peroneus  longus, 
flexor  brevis  minimi  digiti,  and  tibialis  anticus.  The  first  four  muscles 
diminish  the  span,  and  so  deepen  the  arch,  whilst  the  tibialis  anticus  increases 
the  span,  and  so  renders  the  arch  wider. 

The  Tarso-metatarsal  Joints. 

The  tarso-metatarsal  joints  are  divided  into  internal,  middle, 
and  external.  They  all  belong  to  the  class  diarthrosis,  and  to  the 
subdivision  arthrodia. 

I.  Internal  Tarso-metatarsal  Joint. — This  is  the  joint  between  the 
internal  cuneiform  and  the  first  metatarsal  bone.  The  dorsal  and 
plantar  ligaments  of  this  joint  are  so  disposed  as  to  meet  u])on  its 
inner  and  outer  aspects,  and  thus  a  complete  capsule  is  formed  round 
the  articulation,  which  capsule  is  stronger  interiorly  and  internally 
than  elsewhere. 

The  synovial  membrane  of  this  joint  is  peculiar  to  it. 

II.  Middle  Tarso-metatarsal  Joint. — The  bones  which  enter  into 
this  joint  are  the  three  cuneiforms  and  the  bases  of  the  second  and 
third  metatarsals  (sometimes  a  })art  of  the  base  of  the  fourth  also). 
The  ligaments  are  dorsal,  })lantar,  and  interosseous. 

The  dorsal  ligaments. — The  dorsal  surface  of  the  base  of  the 
second  metatarsal  bone  receives  three  dorsal  ligaments,  one  from 
each  cuneiform.  The  dorsal  surface  of  the  base  of  the  third  meta- 
tarsal bone  receives  a  dorsal  ligament  from  tlu;  external  cimei- 
form.  Moreover,  the  external  crmeiform  is  connected  by  a  dorsal 
ligamtmt  wifli  the  dorsal  surface  of  the  base  of  the  fonrlli  nicl.ilars.il 
bone. 

The  plantar  ligaments  are  three  in  numljer.  One  [Kisses  l)etvv((ii 
the  base  of  the  internal  cuneiform  and  the  i)lantar  aspects  of  the 


552  A  MANUAL  OF  ANATOMY 

bases  of  the  second  and  third  metatarsals,  having  the  shps  of  the 
tendon  of  the  tibiahs  posticus  behind  it ;  a  second  passes  between 
the  middle  cuneiform  and  the  base  of  the  second  metatarsal ;  and 
a  third  passes  between  the  external  cuneiform  and  the  base  of  the 
third  metatarsal,  the  latter  two  also  having  the  slips  of  the  tendon 
of  the  tibialis  posticus  behind  them. 

The  interosseous  ligaments  are  three  in  number — internal,  middle, 
and  external. 

The  internal  interosseous  ligament  extends  from  the  anterior  and 
upper  part  of  the  outer  surface  of  the  internal  cuneiform  to  the 
inner  surface  of  the  base  of  the  second  metatarsal.  In  each 
case  it  is  attached  below  and  in  front  of  the  articular  facet,  and 
it  separates  the  internal  from  the  middle  tarso-metatarsal  joint.  It 
is  a  very  strong  ligament,  and  offers  considerable  resistance  to  the 
knife  in  the  performance  of  Lisfranc's  operation.  The  middle  inter- 
osseous ligament  extends  from  the  anterior  part  of  the  inner  surface 
of  the  external  cuneiform,  between  the  two  semi-oval  facets,  to  the 
groove  on  the  outer  surface  of  the  base  of  the  second  metatarsal 
which  separates  the  two  facets.  The  external  interosseous  ligament 
extends  from  the  anterior  part  of  the  outer  surface  of  the  external 
cuneiform,  below  the  inconstant  antero-superior  facet,  to  the  outer 
side  of  the  base  of  the  third  metatarsal  below  the  facet.  It  is  also 
attached  to  the  inner  side  of  the  base  of  the  fourth  metatarsal, 
and  it  ranks  as  the  interosseous  ligament  of  the  cubo-metatarsal 
joint. 

The  synovial  membrane  of  the  middle  tarso-metatarsal  joint  is 
usually  continuous  with  that  of  the  naviculo-cuneiform  joint,  the 
continuity  taking  place  between  the  internal  and  middle  cuneiform 
bones .  Sometimes,  however,  they  are  quite  distinct  from  each  other. 
It  sends  prolongations  forward  between  the  bases  of  the  second  and 
third  and  third  and  fourth  metatarsals. 

III.  External  Tarso-metatarsal  or  Cubo-metatarsal  Joint. — The 
bones  which  enter  into  this  joint  are  the  cuboid  and  the  fourth  and 
fifth  metatarsals.  The  ligaments  are  dorsal,  plantar,  and  inter- 
osseous. 

The  dorsal  ligament  passes  from  the  dorsal  surface  of  the  cuboid 
to  the  dorsal  surfaces  of  the  bases  of  the  fourth  and  fifth  metatarsals. 

The  plantar  ligament  extends  between  the  plantar  surface  of  the 
cuboid  in  front  of  the  peroneal  groove  and  the  plantar  aspects  of 
the  bases  of  the  fourth  and  fifth  metatarsals.  It  is  closely  asso- 
ciated with  the  forward  expansion  of  the  long  plantar  ligament  and 
with  one  of  the  slips  of  the  tendon  of  the  tibialis  posticus. 

The  interosseous  ligament  is  the  same  as  the  external  interosseous 
ligament  of  the  middle  tarso-metatarsal  joint. 

The  dorsal,  plantar,  and  interosseous  ligaments  construct  a 
capsule  round  the  cubo-metatarsal  joint. 

The  synovial  membrane  is  peculiar  to  this  joint,  and  sends  a 
prolongation  between  the  bases  of  the  fourth  and  fifth  metatarsals. 

Arterial  Supply. — The  tarso-metatarsal  joints  derive  their  arterial 


T'^E  LOWER  LIMB  553 

supply  from  the  dorsalis  pedis  artery  and  its  metatarsal  branch 
the  mternal  plantar  artery,  and  the  plantar  arch. 

Nerve-supply.— The  dorsalis  pedis,  internal  plantar,  and  external 
plantar  nerves. 

Movements  at  the  Tarso-metatarsal  Joints.— The  movements  allowed  are 
Hexion  and  extension.  At  the  internal  tarso-metatarsal  joint  flexion  is 
associated  with  a  certain  amount  of  abduction,  whilst  extension  is  accom- 
panied by  shght  adduction.  At  the  middle  tarso-metatarsal  joint  flexion 
and  extension  are  allowed,  but  no  lateral  movement.  At  the  cubo-metatarsal 
joint  tie.xion  and  extension,  combined  with  abduction  and  adduction  are 
allowed,  lateral  movement  being  tolerably  free  in  the  case  of  the  fifth  meta- 
tarsa  .  A  certain  amount  of  gliding  or  to-and-fro  movement  is  also  per- 
missible at  the  tarso-metatarsal  joints  in  the  following  manner  •  the  third 
metatarsal  base  can  glide  upwards,  whilst  the  pair  on  either  side  of  it  can  glide 
downwards,  the  effect  being  to  diminish  the  span  of  the  transverse  arch  of  the 
loot      \\  hen  the  reverse  movement  takes  place  the  span  of  the  arch  is  increased. 

the  portion  of  the  transverse  arch  which  is  formed  by  the  bases  of  the 
metatarsal  bones  has  the  following  muscles  attached  to  its  various  parts  • 
tibiahs  posticus,  adductor  obhquus  hallucis,  peroneus  longus  flexor  brevis 
minimi  digiti,  and  tibialis  anticus.  The  first  three  muscles  diminish  the 
span,  and  so  deepen  the  arch,  whilst  the  tibialis  anticus  increases  the  span 
and  so  renders  the  arch  wider.  ' 

Surgical  Anatomy  of  the  Tarso-metatarsal  Joints.— It  is  in  this  situation 
where  Lisfranc's  and  Hey's  amputations  are  performed.  The  guide  to  the 
line  of  articulation  on  the  outer  border  of  the  foot  is  the  tuberosity  on  the 
outer  side  of  the  base  of  the  fifth  metatarsal,  which  can  always  be  felt 
without  difficulty.  The  joint  between  the  cuboid  and  the  fifth  metatarsal 
IS  situated  immediately  behind  this  tuberosity.  The  guide  to  the  line  of 
articulation  on  the  inner  border  of  the  foot  is  a  point  U  inches  in  front  of  the 
tuberosity  of  the  navicular  bone.  The  hne  of  articulation  is  in  no  sense 
transverse,  its  inner  part  being  about  i  inch  further  forwards  than  the  outer 
part.  Ihe  tarso-metatarsal  joints  are  remarkable  for  their  irregularity  which 
IS  due  to  two  causes.  In  the  first  place,  the  anterior  surfaces  of  the  three 
cuneiform  bones  do  not  present  an  even  frontage.  The  internal  and  external 
cuneiform  project  further  forwards  than  the  middle  cuneiform  and  so  a 
recess  is  formed  which  receives  the  base  of  the  second  metatarsal  as  that 
extends  backwards  to  articulate  with  the  middle  cuneiform.  The  base  of 
the  second  metatarsal  thus  becomes  locked  between  the  internal  and  external 
cuneiform.  In  the  second  place,  the  external  cuneiform  extends  a  little 
further  forwards  than  the  cuboid.  The  line  of  the  tarso-metatarsal  articula- 
tions, from  the  inner  border  of  the  foot  to  the  outer  border,  is  as  follows  : 
(I)  outwards,  between  the  internal  cuneiform  and  first  metatarsal  •  (2)  hack- 
wards,  iors-howi  4  inch  (at  this  stage  a  very  strong  interosseous  ligament  has 
to  be  divided,  as  it  passes  between  the  internal  cuneiform  and  the  inner  side 
of  the  base  of  the  second  metatarsal  ;  (3)  outwards,  between  the  middle 
cuneiform  and  second  metatarsal  ;  (4)  forwards,  for  about  \  inch  ;  is)  outwards, 
between  the  external  cuneiform  and  third  metatarsal  ;  (6)  backwards,  for 
about  i  incii  ;  and  (7)  outwards  and  backwards,  between  the  cuboid  and  the 
fourth  and  fifth  metatarsals. 

The  Intermetatarsal  Joints. 

The  basal  intermetatarsal  joints  belong  to  the  class  diarthrosis, 
and  to  the  subdivision  arthrodia.  The  bones  concerned  arc;  (he 
outer  four  metatarsals.  The  first  metatarsal  Iione  does  not  usually 
articulate  with  the  second,  but  sometimes  it  does.  The  ligaments 
are  dorsal,  plantar,  and  interosseous. 


SS4 


A  MANUAL  OF  ANATOMY 


The  dorsal  ligaments  are  short  transverse  bands,  three  in  number, 
which  pass  between  the  dorsal  aspects  of  the  bases  of  the  second 
and  third,  third  and  fourth,  and  fourth  and  fifth  metatarsals. 

The  plantar  ligaments  are  disposed  in  a  similar  manner  to  the 
preceding  on  the  plantar  aspects  of  the  bases  of  the  four  outer 
metatarsals. 

The  interosseous  ligaments,  which  are  three  in  number,  are 
deeply  placed  and  of  considerable  strength.  They  constitute  a 
very  firm  bond  of  union  between  the  contiguous  sides  of  the  bases 
of  the  outer  four  metatarsals,  to  the  non-articular  parts  of  which 
they  are  attached. 

Synovial  Membrane. — In  the  case  of  the  joints  between  the 
bases  of  the  second  and  third  and  third  and  fourth  metatarsals 
the  synovial  membrane  is  a  forward  extension  of  that  of  the  middle 
tarso-metatarsal  joint,   which    sends    forward    two  prolongations. 


Interosseoub  I  igament 


Fig.  265. — The  Synovial  Cavities  of  the  Tarsal  and 
Tarso-metatarsal  Joints. 

In  the  case  of  the  joint  between  the  bases  of  the  fourth  and  fifth 
metatarsals  the  synovial  membrane  is  a  forward  prolongation  of 
that  of  the  cubo-metatarsal  joint.  As  regards  the  contiguous 
sides  of  the  bases  of  the  first  and  second  metatarsals,  if  they  should 
articulate,  a  special  synovial  bursa  is  usually  provided  which  some- 
times communicates  with  the  synovial  membrane  of  the  internal 
tarso-metatarsal  joint. 

The  arterial  supply  and  nerve-supply  are  derived  from  the  same 
sources  as  in  the  case  of  the  tarso-metatarsal  joints. 

Movements. — These  are  of  a  purely  gliding  or  to-and-fro  nature,  so  as  to 
increase  or  diminish  the  span  of  the  transverse  arch  of  the  foot. 

The  heads  of  all  the  metatarsal  bones  are  connected  by  the 
transverse  metatarsal  (deep  transverse)  ligament,  which  extends 
across  their  plantar  aspects.  Its  fibres  are  attached  to  the  fibrous 
plates  on  the  plantar  surfaces  of  the  metatarso-phalangeal  joints, 


THE  LOWER  LIMB  555 

and  it  receives  the  deep  expansions  of  the  digital  processes  of  the 
central  division  of  the  plantar  fascia.  It  is  to  be  noted  that  the 
transverse  metatarsal  ligament  includes  the  head  of  the  first 
metatarsal  bone,  whereas  the  corresponding  ligament  in  the  hand 
(transverse  metacarpal)  excludes  the  head  of  the  first  metacarpal 
bone. 

Summary  of  the  Tarsal  and  Tarso- metatarsal  Synovial  Membranes. 

— These  are  usually  six  in  numlier. 

1.  Posterior  astragalo-calcaneal. 

2.  Astragalo-calcaneo-navicular. 

3.  Calcaneo-cuboid. 

4.  Xaviculo-cuneiform,  cubo-cuneiform,  cubo-navicular  (incon- 
stant), intercuneiform,  and  middle  tarso-metatarsal. 

5.  Internal  tarso-metatarsal. 

6.  External  tarso-metatarsal  or  cubo-metatarsal. 

Sometimes  the  middle  tarso-metatarsal  synovial  membrane  is 
distinct  from  the  naviculo-cuneiform  and  intercuneiform  synovial 
membrane,  in  which  case  the  number  would  be  increased  to  seven. 
Occasionally  the  cubo-cuneiform  synovial  membrane  is  distinct 
from  the  naviculo-cuneiform  and  intercuneiform,  in  which  case 
there  would  be  eight  synovial  membranes.  In  addition  to  these, 
there  may  be  a  synovial  bursa  between  the  contiguous  sides  of  the 
bases  of  the  first  and  second  metatarsals  if  these  articulate  with 
each  other,  as  they  sometimes  do. 


The  Metatarso-phalangeal  Joints. 

These  joints  belong  to  the  class  diarthrosis,  and  to  the  subdivision 
condylarthrosis  or  condyloid  joint.  They  are  formed  by  the  heads 
of  the  metatarsal  bones  and  the  proximal  ends  of  the  first 
phalanges.  The  ligaments  of  the  four  outer  joints  are  three  in 
number,  two  lateral  and  an  inferior  or  plantar  fibrous  plate.  In  the 
metatarso-phalangeal  joint  of  the  great  toe  the  plantar  fibrous 
plate  of  the  other  joints  is  replaced  by  two  sesamoid  bones,  which 
are  closely  associated  with  the  heads  of  insertion  of  the  flexor 
brevis  hallucis.  In  the  case  of  each  joint  the  expansion  of  an 
extensor  tendon  serves  the  jiurpose  of  a  dorsal  ligament.  Each 
joint  is  i)rovided  with  a  synovial  membrane.  The  ligaments, 
synovial  membranes,  and  movements  of  these  joints  closely 
correspond  with  those  of  the  metacarpo-phalangeal  joints.  Abduc- 
tion, adduction,  and  circumduction,  however,  are  much  more 
limited. 

Arterial  Supply. — The  plantar  digital  and  dorsal  interosseous 
arteries. 

Nerve-supply. —Tlie  deeji  division  of  the  external  plantar  nerve 
(cither  directly  or  through  its  l^ranches  to  the  interosseous  muscles), 
or  the  adjacent  digital  nerves. 


556 


A   MANUAL  OF  ANATOMY 


;|The|Interphalangeal  Joints. 

G  These  joints  belong  to  the  class  diarthrosis,  and  to  the  subdivision 
ginglymus.  They  are  formed  by  the  distal  end  of  one  phalanx 
and  the  proximal  end  of  the  adjoining  phalanx.  The  ligaments  are 
three  in  number,  two  lateral  and  an  inferior  or  plantar  fibrous  plate, 
the  extensor  tendon  taking  the  place  of  a  dorsal  hgament.  Each 
joint  is   provided  with  a   synovial   membrane.      The    ligaments, 


Fig.  266. — Sagittal  Section  of  Ankle  and  Foot,  passing  through 
THE  Great  Toe. 

I,  Spring  Ligament ;  2,  Inner  Sesamoid  Bone. 

synovial  membranes,  and  movements  of  these  joints  closely  corre- 
spond with  those  of  the  interphalangeal  joints  of  the  hand. 

The  only  joint  in  the  lower  limb  which  has  interarticular  fibro-cartilages 
is  the  knee-joint.  The  hip-joint  has  a  circumferential  fibro-cartilage,  namely, 
the  cotyloid  ligament. 


GUIDE  TO  THE  LOWER  LIMB. 


Gluteal  Region. — The  landmarks  having  been  studied,  the  skin  is  to  be  re- 
moved by  making  the  following  incisions :  one  extending  from  the  level  of  the 
spine  of  the  fifth  lumbar  vertebra  outwards  along  the  iliac  crest  as  far  as  the 
position  of  the  body  will  allow,  and  another  extending  from  the  fifth  lumbar 
spine  downwards  in  the  middle  line  as  low  as  the  coccyx,  after  which  it  is 
prolonged  outwards  and  downwards  to  the  outer  side  of  the  thigh  at  a  point 
about  5  inches  below  the  great  trochanter.  The  skin  having  been  reflected, 
the  gluteal  cutaneous  nerves  are  to  be  exposed  in  the  following  situations  : 
(i)  line  of  origin  of  gluteus  maximus  ;  (2)  iliac  crest  ;  (3)  outer  and  lower  part 
of  gluteus  maximus  ;  and  (4)  lower  border  of  gluteus  maximus.  The  super- 
ficial fascia  should  now  be  removed,  and  the  deep  fascia  examined.  It  will 
be  seen  that,  in  passing  from  the  gluteus  medius  to  the  gluteus  maximus,  it 
firmly  straps  down  the  upper  border  of  the  latter  muscle  to  the  former. 
When  the  gluteus  maximus  has  been  reflected,  the  fascia  will  be  seen  to  divide 
into  two  laminae,  which  embrace  and  give  insertion  to  rather  more  than  the 
upper  half  of  that  muscle. 


THE  LOWER  LIMB  ct„ 

55/ 

The  gluteus  maximus  should  he  cleaned  in  the  direction  of  its  coarse 
fascicuh,  and  in  connection  with  its  lower  border  the  bursa  between  it  and 
the  tuber  ischu  should  be  displayed.  The  muscle  is  to  be  divided  about  ji 
inches  from  its  ongin.  As  the  greater  part  of  it  is  being  reflected  outwards' 
the  following  arteries  should  be  exposed  entering  its  deep  surface  :  the 
superhcial  branch  of  the  gluteal,  the  inferior  gluteal  branch  of  the  sciatic 
and  branches  of  the  first  perforating  of  the  arteria  profunda  femoris  The 
inferior  gluteal  nerve  should  also  be  shown  entering  the  deep  surface  of 
the  muscle  in  its  lower  third.  Between  the  great  trochanter  and  the 
insertion  of  the  muscle  into  the  fascia  lata  a  large  multilocular  bursa 
will  be  found,  and  another  single  bursa  should  be  noticed  between  its  insertion 
and  the  vastus  externus  just  below  the  great  trochanter.  The  twofold  inser- 
tion of  the  muscle  should  be  noted.  The  origin  of  the  muscle  is  now  to  be 
removed  so  as  to  expose  the  great  sacro-sciatic  ligament  and  the  structures 
piercing  it  namely,  the  coccygeal  branch  of  the  sciatic  artery,  the  sacral 
branch  of  the  internal  pudic  artery,  and  the  perforating  cutaneous  branch  of 
the  sacral  plexus  of  nerves.  On  the  superficial  surface  of  the  Hgament  will  be 
found  the  plexiform  loops  formed  by  the  external  branches  of  the  posterior 
primary  divisions  of  the  first  three  sacral  nerves. 

The  fascia  lata  should  next  be  removed  from  the  anterior  part  of  the 
gluteus  medius,  and  m  doing  so  it  should  be  noted  that  the  superficial 
fibres  of  the  muscle  arise  from  the  deep  surface  of  the  fascia.  The  various 
structures  underneath  the  gluteus  maximus  are  to  be  cleaned  from  above 
dovvnwards,  as  follows:  the  posterior  fleshy  part  of  the  gluteus  medius 
gluteal  vessels,  pyriformis,  great  and  small  sciatic  nerves,  sciatic  vessels' 
pudic  nerve  and  internal  pudic  vessels,  nerve  to  the  obturator  internus' 
furnishing  a  branch  to  the  gemellus  superior,  common  nerve  to  the  gemellus 
in  erior  and  quadratus  femoris,  gemellus  superior,  tendon  of  the  obturator 
internus,  gemellus  inferior,  quadratus  femoris,  upper  horizontal  part  of  the 
adductor  magnus,  origins  of  the  hamstring  muscles  from  the  tuber  ischii 
and  the  upper  tendinous  fibres  of  the  vastus  externus.  The  digital  and 
crucial  anastomoses  should  be  looked  for,  the  former  in  the  digital  or  tro- 
chanteric fossa,  and  the  latter  between  the  quadratus  femoris  and  adductor 
magnus. 

The  small  sciatic  nerve  should  be  displayed  so  as  to  show  its  long  pudendal 
branch,  and  the  great  sciatic  nerve  is  to  be  exposed  in  the  hollow  between 
the  tuber  ischii  and  the  great  trochanter.  The  sciatic  artery  and  its  branches 
are  to  be  fo  lowed  out.  The  pudic  nerve,  the  internal  pudic  vessels,  and 
the  nerve  to  the  obturator  internus  (with  its  branch  to  the  gemellus  superior) 
are  to  be  shown  as  they  cross  the  back  of  the  spine  of  the  ischium  The 
tendon  of  the  obturator  internus  should  be  divided  to  show  the  columns  on 
its  under  surface,  the  synovial  bursa  between  the  tendon  and  the  small 
sciatic  no  ch,  and  the  cartilage  facing  that  notch,  with  its  grooves  an 
ndges  for  the  columns  of  the  tendon.  The  sacro-sciatic  hgaments,  great  and 
small,  should  be  studied.  The  mode  of  formation  of  the  great  and  smal 
sacro-sciatic  foramina  should  be  made  out,  and  the  various  structures  passing 

hrough  each  should  be  noted.  The  upper  border  of  the  quadratus  femoris  it 
to  be  disp  aced  downwards  so  as  to  show  the  obturator  externus  and  the 
dSTrfssn'^^Th"  '^'  'r''?^^  circumflex  artery,  both  on  their  way  to  the 
digital  fossa.  Ihe  lower  border  of  the  quadratus  femoris  should  be  raised  to 
show  the  small  trochanter  and  the  insertion  of  the  ilio-psoas  in  part  The 
common  nerve  to  the  gemellus  inferior  and  quadratus  femoris  will  be  found 
at  first  underneath  the  great  sciatic  nerve,  and  subsequently  passing  beneath 
the  gemelli    obturator  internus,  and  quadratus  femoris.     Its  articular  branch 

o  the  hip-joint  should  be  looked  for.  If  absent,  its  place  will  be  taken  by  a 
branch  from  the  great  sciatic  nerve.  ^ 

thJ  Hnr«n!^"fli"''''^'?iK''?P*  it.s  anterior  fibres)  should  now  be  stripped  from 
the  dorsum  il u,  and   the  bone  cleaned  by  scraping,  so  as  to  show   the  exact 

mmL'^rsTtn  /^'  T'"''^^-  J^'  P.ynforn^is  being  also  divided,  the  gluteus 
minimus  IS  to  be  cleaned,  along  witli  the  upper  and  lower  branches  of  the 
deep  divisions  of  the  gluteal  artery  and  superior  gluteal  nerve.     One  of  each 


5S8       •  A   MANUAL  OF  ANATOMY 

of  these  structures  will  be  found  coursing  along  the  upper  border  of  the  gluteus 
minimus,  and  crossing  outwards  over  its  centre.  The  latter  branch  (lower)  of 
the  artery  should  be  shown  to  give  a  branch  to  the  digital  fossa  to  take  part 
in  the  digital  anastomosis,  and  the  corresponding  branch  of  the  superior  gluteal 
nerve  should  be  followed  outwards  to  the  outer  aspect  of  the  thigh  as  far  as 
possible  on  its  way  to  the  tensor  fasciae  femoris,  which  it  supplies.  The 
gluteus  minimus  (except  its  anterior  fibres)  is  to  be  stripped  from  the  bone, 
after  which  the  surface  thereby  exposed  should  be  cleaned.  The  posterior 
or  reflected  head  of  the  rectus  femoris  is  to  be  shown  arising  from  the  dorsum 
ilii  immediately  above  the  brim  of  the  acetabulum.  The  muscular  relations 
of  the  capsular  ligament  of  the  hip-joint  should  be  carefully  attended  to  in 
so  far  as  the  position  of  the  body  will  allow. 

Popliteal  Space. — This  space  should  be  dissected  before  the  structures  on 
the  back  of  the  thigh  are  disturbed.  The  landmarks  having  been  studied, 
the  skin  is  to  be  removed  by  the  following  incisions  :  ( i )  a  median  vertical 
incision  extending  from  the  junction  of  the  upper  two- thirds  and  lower  third 
of  the  thigh  to  the  junction  of  the  upper  fourth  and  lower  three-fourths  of 
the  leg  ;  and  (2)  two  transverse  incisions,  one  at  either  end  of  the  median 
incision. 

The  small  sciatic  nerve  is  to  be  displayed  after  it  pierces  the  fascia 
lata  at  the  back  of  the  knee-joint,  and  it  should  be  followed  to  its  terminal 
distribution  over  the  upper  part  of  the  back  of  the  leg.  The  upper  part  of 
the  external  or  short  saphenous  vein  is  to  be  dissected,  and  in  connection  with 
it  the  following  two  veins  should  be  noticed  :  (i)  a  fairly  large  tributary 
vessel,  which  descends  from  the  lower  part  of  the  back  of  the  thigh  ;  and 
(2)  a  communicating  branch,  which  passes  upwards  and  inwards  to  join  the 
long  saphenous  vein.  Three  cutaneous  sural  arteries  (branches  of  the  popliteal) 
may  be  looked  for — an  external,  over  the  outer  head  of  the  gastrocnemius  ;  an 
internal,  over  the  inner  head  ;  and  a  middle,  accompanying  the  short  saphenous 
vein.  The  fascia  lata  should  next  be  cleaned,  and  the  accession  of  strength 
which  it  here  receives  from  superadded  transverse  fibres  should  be  observed. 
Above  the  level  of  the  knee-joint  the  small  sciatic  nerve  will  be  found  in 
the  middle  line  beneath  the  fascia  lata.  This  fascia  is  now  to  be  removed, 
and  the  boundaries  of  the  popliteal  space  are  to  be  cleaned. 

The  principal  contents  of  the  space  are  to  be  displayed  by  the  removal  of 
a  large  amount  of  fat.  The  great  sciatic  nerve  should  be  exposed  close  to 
the  upper  median  angle,  and  its  external  and  internal  popliteal  branches 
cleaned  downwards  from  that  point.  The  external  popliteal  nerve  is  to  be 
followed  along  the  inner  border  of  the  biceps  femoris  as  far  as  a  point  just 
below  the  head  of  the  fibula.  In  cleaning  this  nerve,  the  dissector  should 
look  for  the  following  branches,  namely,  (i)  superior  articular,  to  accom- 
pany the  superior  external  articular  artery  ;  (2)  inferior  articular,  to  accompany 
the  inferior  external  articular  artery;  (3)  lateral  cutaneous,  to  the  integument 
of  the  outer  side  of  the  leg  over  about  its  upper  two-thirds  ;  and  (4)  ramus 
communicans  fibularis,  which  passes  downwards  and  inwards  to  the  middle 
line  of  the  calf  on  its  way  to  join  the  ramus  communicans  tibialis,  and  so  form 
the  external  or  short  saphenous  nerve. 

The  internal  popliteal  nerve  is  to  be  followed  through  the  centre  of  the 
space  as  low  as  the  interval  between  the  heads  of  the  gastrocnemius.  In 
cleaning  it,  the  following  branches  should  be  looked  for  :  (i)  superior  articular 
(inconstant),  to  accompany  the  superior  internal  articular  artery  ;  (2)  central 
or  azygos  articular,  to  accompany  the  corresponding  artery  ;  (3)  inferior 
articular,  to  accompany  the  inferior  internal  articular  artery ;  (4)  ramus 
communicans  tibialis,  which  takes  a  straight  course  downwards  to  the  calf, 
where  it  forms  the  chief  part  of  the  external  or  short  saphenous  nerve  ;  and 
(5 )  four  or  five  muscular  (sural)  branches,  as  follows  :  («)  one  to  the  outer  head 
of  the  gastrocnemius  ;  (6)  one  to  the  plantaris  (which  sometimes  comes  from 
the  preceding  branch)  ;  (c)  one  to  the  inner  head  of  the  gastrocnemius  ; 
{d)  one  to  the  soleus  ;  and  [e]  one  to  the  popUteus.  The  nerve  to  the 
popliteus  should  be  preserved  with  great  care. 

The  internal  popliteal  nerve  should  be  hooked  to  one  side,  and  the  popliteal 


THE  LOWER  LIMB 


359 


vein  exposed,  its  van-ing  relation  to  the  more  deeply-placed  popliteal  arterj' 
being  noted.  The  tributaries  of  the  popliteal  vein,  when  dissected,  should 
be  cut.  These  correspond  with  the  branches  of  the  popliteal  arterv,  the 
short  saphenous  vein  being  a  special  tributary.  The  vein  should  next  be 
hooked  to  one  side,  which  will  prepare  the  popliteal  artery  for  dissection.  In 
order  to  expose  the  vessel  fully  to  its  termination,  the  inner  head  of  the 
gastrocnemius  may  be  divided.  In  cleaning  the  artery,  the  geniculate  branch 
of  the  obturator  nerve  should  be  looked  for.  If  present,  it  will  be  found  piercing 
the  adductor  magnus  close  above  the  femoral  opening,  after  which  it  usually 
descends  at  first  upon  the  inner  side  of  the  artery  and  then  in  front  of  it, 
until  it  comes  into  contact  with  the  central  or  azj-gos  branch,  which  it 
accompanies  through  the  posterior  ligament  of  the  knee-joint  to  the  interior 
of  the  articulation.  During  this  dissection  the  popliteal  lymphatic  glands 
may  come  into  view  in  the  interval  between  the  femoral  condyles,  one  gland 
being  superficial  to  the  artery,  one  beneath  it,  and  one  on  either  .side.  The 
branches  of  the  artery  are  to  be  carefully  cleaned,  as  follows:  (i)  muscular,  to 
the  hamstring  and  sural  muscles  ;  (2)  cutaneous,  to  the  upper  part  of  the 
back  of  the  leg  ;  and  (3)  the  following  live  articular  arteries  :  (a)  two 
superior,  external  and  internal,  above  the  knee-joint,  usually  close  above 
the  femoral  condyles  and  lying  very  deeply  ;  (b)  central  or  azygos,  at  the 
back  of  the  joint,  and  coming  either  from  the  front  (deep)  surface  of  the 
main  vessel,  or  in  many  cases  from  the  superior  external  articular  ;  and  (c)  two 
inferior,  external  and  internal,  below  the  level  of  the  joint.  The  floor  of  the 
popliteal  space  should  next  be  cleaned  and  examined,  as  follows:  (i)  the 
popliteal  surface  or  trigone  of  the  femur  ;  (2)  the  posterior  ligament  of  the 
knee-joint,  with  the  ligamentum  posticum  Winslowii  ;  and  (3)  the  popliteal 
fascia  covering  the  popliteus  muscle. 

Back  of  the  Thigh. — The  landmarks  having  been  studied,  the  skin  is  to  be 
removed  by  making  a  single  vertical  incision  in  the  middle  hne.  In  the 
superficial  fascia  the  femoral  cutaneous  branches  of  the  small  sciatic  nerve 
are  to  be  looked  for,  along  the  inner  and  outer  aspects.  At  the  upper  and 
inner  part  of  the  back  of  the  tliigh  twigs  may  be  met  with  from  the  long 
pudendal  branch  of  the  small  sciatic  nerve. 

The  superficial  fascia  having  been  removed,  the  deep  fascia  or  fascia  lata 
should  be  studied.  The  deep  fascia  having  been  removed,  the  small  sciatic 
nerve  should  be  shown,  and  the  hamstring  muscles,  namely,  the  biceps 
femoris,  semitendinosus,  and  semimembranosus,  should  be  cleaned  and 
studied.  The  relation  of  the  long  head  of  the  biceps  to  the  great  sacro- 
sciatic  ligament  should  be  noted. 

The  great  sciatic  nerve  is  also  to  be  cleaned  to  its  division  into  external 
and  internal  popliteal  nerves,  which  latter  nerves  sometimes  take  the  place 
of  the  great  sciatic.  The  muscular  branches  of  the  great  sciatic  should  be 
dissected,  and  it  should  be  noted  that,  with  one  exception,  they  are  derived 
from  the  internal  popliteal  part  of  the  nerve.  The  exception  is  the  branch 
to  the  femoral  head  of  the  biceps,  which  is  derived  from  the  external  popliteal 
part  of  the  nerve.  It  should  also  be  noted  that  the  nerve  to  the  semimembra- 
nosus gives  a  branch  to  that  part  of  the  adductor  magnus  which  extends  from 
the  tuber  i.schii  to  the  adductor  tubercle  of  the  femur.  The  whole  course 
and  relations  of  the  great  sciatic  nerve  should  be  thoroughly  mastered. 
Th*e  posterior  surface  of  the  adductor  magnus  should  next  be  cleaned,  showing 
the  four  arches  with  the  four  perforating  arteries  passing  backwards  under 
them,  and  the  femoral  opening  where  the  femoral  artery  becomes  the  popliteal. 

The  distribution  and  anastomoses  of  the  perforating  arteries  on  the  back  of 
the  thigh  should  be  carefully  studied,  and  it  should  be  noted  that  they  com- 
municate above  with  the  sciatic  and  gluteal,  and  below  with  the  popUteal.  It 
should  further  be  noted  that  the  perforating  arteries  do  not  terminate  on 
the  back  of  the  thigh,  and  for  this  purpose  an  elfort  should  be  made  to  show 
all  four  passing  outwards  preparatory  to  their  winding  round  tiie  outer  side 
of  the  femur  to  the  outer  side  of  the  thigh,  inwhicli  situation  they  end.  The 
relation  of  muscles  at  the  gluteal  ridge  of  the  femur  should  be  studied,  as 
well  as  the  relation  of  muscles  along  the  linea  asijcra. 


56o  A  MANUAL  OF  ANATOMY 

Front  of  the  Thigh. — The  dissector  should  make  himself  thoroughly  familiar 
with  the  landmarks  of  the  front  of  the  thigh  and  of  the  knee.  The  first 
dissection  should  be  limited  to  the  upper  4  inches  in  connection  with  the  parts 
involved  in  femoral  hernia.  For  this  purpose  three  incisions  are  required 
for  the  removal  of  the  skin,  as  follows :  one  along  the  line  of  the  groin  from 
the  anterior  superior  iliac  spine  to  the  pubic  angle,  a  second  extending  from 
the  pubic  angle  vertically  downwards  along  the  inner  side  of  the  thigh  for 
4  inches,  and  a  third  extending  from  the  lower  end  of  the  second  incision 
transversely  across  the  front  of  the  thigh  as  far  as  its  outer  aspect. 

It  is  to  be  desired  that  the  subsequent  dissection,  which  has  to  do  with  the 
superficial  fascia  and  cutaneous  vessels,  should  be  undertaken  in  concert  with 
the  dissector  of  the  abdomen.  The  superficial  fascia  in  this  region  should  be 
shown  to  be  divisible  into  a  subcutaneous  fatty  layer  and  a  deep  thin  mem- 
branous layer,  which  correspond  with  Camper's  and  Scarpa's  fasciae  of  the 
lower  part  of  the  anterior  abdominal  wall.  In  order  to  reflect  the  subcu- 
taneous layer,  a  transverse  incision  should  be  carefully  made  across  the  thigh, 
the  depth  of  this  incision  coinciding  internally  with  the  long  saphenous  vein, 
which  lies  between  the  two  layers  of  the  superficial  fascia.  Another  incision 
should  be  made  vertically  upwards  on  the  inner  side  of  the  thigh,  and  extending 
only  through  the  subcutaneous  layer.  Acting  simultaneously  with  the 
dissector  of  the  abdomen,  the  dissector  of  the  thigh  can  now  reflect  outwards 
the  subcutaneous  layer,  and  both  dissectors  will  see  that  it  is  continuous  over 
Poupart's  ligament  with  Camper's  fascia  of  the  anterior  abdominal  wall. 
Care  should  be  taken  not  to  disturb  the  lymphatic  glands  of  this  region. 
The  inguinal  glands  (including  the  pubic  glands)  and  the  superficial  femoral 
or  saphenous  glands  are  next  to  be  dissected.  The  former  will  be  found 
lying  with  their  long  axes  oblique  just  below  Poupart's  ligament,  and  the  latter 
with  their  long  axes  vertical  along  the  terminal  part  of  the  long  saphenous 
vein. 

The  cutaneous  arteries  of  the  groin,  with  their  corresponding  veins,  are 
to  be  dissected,  namely,  the  superficial  epigastric,  superficial  circumflex 
iliac,  and  superior  external  pudic.  The  inferior  external  pudic,  being  beneath 
the  fascia  lata,  is  not  to  be  dissected  at  present.  The  terminal  part  of  the 
long  saphenous  vein  should  be  shown,  up  to  the  level  of  the  saphenous 
opening,  and  the  following  tributaries  should  be  displayed  joining  it,  namely, 
the  external  femoral  cutaneous  or  anterior  saphenous  from  the  front  of  the 
thigh,  the  internal  femoral  cutaneous  or  posterior  saphenous  from  the  inner 
and  back  parts  of  the  thigh,  and  the  cutaneous  veins  of  the  groin,  namely, 
the  superficial  epigastric,  superficial  circumflex  ihac,  and  superior  and  inferior 
external  pudic. 

The  deep  layer  of  the  superficial  fascia  is  next  to  be  raised  towards 
Poupart's  ligament.  It  lies  immediately  beneath  the  long  saphenous  vein, 
and  upon  the  deep  fascia  or  fascia  lata.  When  raised  towards  the  groin 
it  will  be  seen  to  cover  the  saphenous  opening,  and  thereafter  to  be  firmly 
bound  down  to  the  fascia  lata  about  \  inch  below  Poupart's  ligament.  The 
portion  of  it  which  covers  the  saphenous  opening  should  be  carefully  studied. 
It  is  called  the  cribriform  fascia,  and  it  should  be  shown  to  be  closely  attached 
to  the  outer  border  of  the  saphenous  opening,  but  only  loosely  to  the  inner 
part.  It  will  be  obvious  that  a  hernia  in  passing  through  the  saphenous 
opening  must  receive  a  covering  from  the  cribriform  fascia. 

The  following  nerves  should  now  be  dissected,  namely,  (i)  branches  of 
the  inguinal  nerve  (so-called  ilio-inguinal),  which  will  be  found  on  the  inner 
aspect  of  the  thigh  ;  (2)  the  crural  branch  of  the  genito-crural,  appearing 
immediately  external  to  the  femoral  artery  just  below  Poupart's  ligament, 
after  having  pierced  the  outer  part  of  the  crural  sheath  ;  and  (3)  the  external 
cutaneous  nerve,  which  will  be  found  emerging  beneath  the  outer  end  of 
Poupart's  ligament. 

The  fascia  lata  is  next  to  be  cleaned,  and  the  saphenous  opening  exposed, 
which  should  be  carefully  dissected.  The  best  starting-point  is  the  in- 
ferior cornu,  which  will  readily  come  into  view  by  raising  the  long  saphenous 
vein.     The  cribriform  fascia  is   to   be   carefully  removed,   and  the  various 


THE  LOWER  LIMB  561 

parts  of  the  opening  displayed.  Before  disturbing  the  opening,  the  dis- 
sector should  note  that  a  part  of  the  anterior  wall  of  the  crural  sheath  is 
seen  Ijang  within  it.  Having  studied  the  saphenous  opening,  the  dissector 
should  now  .separate  the  outer  border  of  the  opening  from  the  anterior  wall 
of  the  crural  sheath  by  di\'iding  the  fibrous  processes  which  connect  them. 
The  superior  cornu  is  next  to  be  detached  from  Poupart's  ligament,  and 
turned  downwards  and  outwards  along  with  the  outer  border  of  the  opening. 
This  \\ill  bring  fully  into  view  the  anterior  wall  of  the  crural  sheath.  The 
deep  crural  arch  should  be  shown  at  this  stage  as  a  bundle  of  fibres  extending 
from  the  centre  of  Poupart's  ligament  on  its  deep  aspect  inwards  over  the 
anterior  wall  of  the  crural  sheath  to  the  pectineal  portion  of  the  iho-pectineal 
line,  where  it  is  attached  behind  Gimbernat's  ligament. 

Having  studied  the  sheath  as  it  now  appears,  and  having  observed  that  the 
crural  branch  of  the  genito-crural  nerve  pierces  the  outer  part  of  the  sheath 
just  below  Poupart's  hgament,  three  vertical  incisions  are  to  be  made  in  its 
anterior  wall — one  over  the  femoral  artery,  another  over  the  femoral  vein,  and 
a  third  a  hne  or  two  internal  to  the  vein.  The  interior  of  the  sheath  should 
then  be  shown  to  be  divided  into  three  compartments  by  means  of  two  septa, 
which  pass  backwards  on  either  side  of  the  femoral  vein.  The  femoral  artery 
and,  for  a  very  limited  distance,  the  crural  branch  of  the  genito-crural  nerve 
should  be  shown  in  the  outer  compartment,  whilst  the  femoral  vein,  having 
on  its  inner  side  two  or  three  of  the  deep  femoral  (deep  inguinal)  glands,  will 
be  found  in  the  middle  compartment.  The  inner  compartment  is  called  the 
crural  canal.  It  is  of  considerable  surgical  importance,  and  should  be  studied 
with  the  closest  attention.  It  will  be  seen  to  contain  a  little  fat,  and  at  its 
upper  end  one  of  the  deep  femoral  glands  will  be  found.  The  dissectors  of 
the  thigh  and  abdomen,  who  should  be  working  in  concert  at  this  stage,  should 
now  thoroughly  explore  the  canal.  The  little  finger  should  be  inserted  into 
it,  and  carried  upwards  to  a  point  beneath  Poupart's  ligament.  At  the  upper 
end  of  the  canal  the  finger  will  detect  the  septum  crurale,  which  shuts  off  the 
canal  from  the  abdominal  cavity.  By  breaking  down  this  septum,  the  point 
of  the  finger  will  lie  in  the  crural  or  femoral  ring,  and  the  sharp  wiry  base  of 
Gimbernat's  ligament  will  readily  be  felt  on  the  inner  side  of  the  ring,  this 
being  the  usual  cause  of  stricture  in  femoral  hernia.  Behind  the  finger  as 
it  hes  in  the  crural  ring  is  Cooper's  ligament.  TMs  structure,  however,  can 
only  be  shown  by  making  a  deep  dissection  of  the  parts  beneath  Poupart's 
ligament,  in  conjunction  with  the  dissector  of  the  abdomen.  The  parts 
around  the  crural  ring  should  be  studied  with  the  greatest  care,  as  it  is  through 
this  ring  and  the  crural  canal  that  femoral  hernia  may  occur. 

The  remainder  of  the  skin  of  the  thigh  is  now  to  be  removed  by  making  a 
vertical  incision  down  the  inner  side  of  the  thigh  to  a  point  just  below  the 
level  of  the  patella,  and  carrying  this  incision  transversely  across  the  front 
of  the  leg  immediately  below  the  patella  on  to  the  outer  aspect  of  the  limb. 
Tliis  will  enable  the  dissector  to  reflect  the  skin  from  the  patella  as  well  as 
from  the  front  of  the  thigh.  The  prepatellar  bursa  will  be  found  lying  in 
front  of  the  bone,  where  it  is  conhned  by  an  expansion  which  the  fascia 
lata  sends  over  the  bone  from  its  lateral  borders. 

A  complete  dissection  of  the  cutaneous  nerves  and  the  femoral  part  of  the 
long  saphenous  vein  is  now  to  be  made.  The  external  cutaneous  nerve, 
which  has  been  already  caught,  should  now  be  followed  out.  Its  small 
posterior  division  and  large  anterior  division  should  be  shown,  and  it  should 
be  noted  that  the  latter  is  contained  in  a  tube  of  fascia  lata  for  about  4  inches 
before  it  enters  the  integument.  The  middle  cutaneous  nerve  will  be  found 
piercing  the  fa.scialata  (usually  in  two  divisions)  about  4  inches  below  Poupart's 
ligament,  and  both  should  be  followed  down  to  the  patellar  plexus,  it  has 
been  seen  that  the  inguinal  nerve  is  distributed  to  the  integument  of  the 
inner  aspect  of  the  thigh  in  its  upper  third.  In  dissecting  the  long  saphenous 
vein  in  the  middle  third  of  the  thigh,  twigs  of  the  internal  cutaneous  nerve 
will  be  met  with  along  the  course  of  that  vein.  There  may  also  be  found 
branches  of  the  subsartorial  plexus  ramifying  in  this  region  (middle  third). 
Another  nerve  which  should   be  looked   for   at  this   level  is  the  cutaneous 

36 


562  A  MANUAL  OF  ANATOMY 

branch  of  the  superficial  or  anterior  division  of  the  obturator  nerve.  When 
present  it  will  usually  be  found  piercing  the  fascia  lata  at  about  the 
centre  of  the  inner  side  of  the  thigh,  between  the  posterior  border  of  the 
sartorius  and  the  anterior  border  of  the  gracilis.  The  two  divisions  of  the 
internal  cutaneous  nerve,  anterior  and  posterior,  should  next  be  dissected. 
The  anterior  division  will  be  found  piercing  the  fascia  lata  at  the  junction 
of  the  middle  and  lower  thirds  of  the  thigh.  It  should  then  be  followed  to 
the  inner  side  of  the  knee  and  patellar  plexus.  The  posterior  division  will 
be  found  piercing  the  fascia  lata  at  the  level  of  the  inner  condyle,  after  which 
it  descends  to  the  inner  side  of  the  leg,  where  it  will  be  afterwards  dissected. 
The  patellar  branch  of  the  internal  or  long  saphenous  nerve  is  to  be  shown. 
It  pierces  the  sartorius  and  the  fascia  lata  at  the  level  of  the  inner  condyle, 
and  should  be  followed  to  the  integument  over  the  patella  and  patellar  plexus. 
The  patellar  plexus  itself  is  to  be  carefully  dissected. 

The  fascia  lata  is  now  to  be  cleaned  and  examined.  Its  deep  processes 
will  only  come  into  view  as  it  is  being  removed  to  expose  the  muscles.  The 
muscles  of  the  front  and  inner  side  of  the  thigh  are  to  be  cleaned  by  removing 
the  fascia  lata.  A  strip  of  this  fascia,  the  so-called  ilio-tibial  band,  about 
2  inches  broad,  and  extending  from  the  fore  part  of  the  iliac  crest  to  the  front 
of  the  external  tuberosity  of  the  tibia,  should  be  preserved.  In  removing  the 
fascia  lata  from  the  pectineus  and  adductor  longus  the  inferior  external  pudic 
artery  is  to  be  dissected. 

The  boundaries  of  Scarpa's  triangle  should  be  defined.  In  the  triangle 
the  following  muscles  should  be  cleaned  from  without  inwards,  namely,  the 
iliacus,  psoas  magnus,  pectineus,  and  adductor  longus.  The  contents  of  the 
triangle  are  now  to  be  cleaned  and  studied,  namely,  (i)  the  anterior  crural 
nerve  ;  (2)  the  common  femoral  and  superficial  femoral  arteries;  (3)  the  origins 
of  the  superficial  epigastric,  superficial  circumflex  iliac,  superior  external  pudic, 
and  inferior  external  pudic  arteries  ;  (4)  the  origin  of  the  arteria  profunda 
femoris,  and  its  external  circumflex  and  internal  circumflex  branches,  and 
(5)  the  femoral  vein  and  its  tributaries.  In  cleaning  the  anterior  crural  nerve 
its  branch  to  the  pectineus  should  be  noted  as  it  passes  inwards  behind  the 
crural  sheath. 

Having  completed  the  superficial  dissection  of  Scarpa's  triangle,  the 
remainder  of  the  sartorius  should  be  cleaned.  The  following  muscles  should 
also  be  cleaned  in  the  order  named  :  tensor  fasciae  femoris,  rectus  femoris, 
and  gracilis.  In  cleaning  the  tensor  fasciae  femoris  the  branch  of  the  superior 
gluteal  nerve  entering  its  deep  surface  should  be  shown  by  dissecting  between 
the  muscle  and  the  gluteus  medius,  the  ilio-tibial  band  should  be  studied, 
and  a  strong  lamina  of  the  fascia  lata  should  be  shown  passing  upwards  on 
the  deep  surface  of  the  muscle  to  the  dorsum  of  the  ilium.  The  two  heads 
of  the  rectus  femoris  should  be  exposed. 

The  sartorius  should  now  be  held  aside  in  the  middle  two-fourths  of  the  thigh, 
in  order  to  study  Hunter's  canal  and  its  contents.  The  aponeurotic  covering 
or  roof  of  the  canal  should  be  shown  as  an  upward  expansion  from  the  tendinous 
anterior  margin  of  the  femoral  opening  in  connection  with  the  adductor  magnus. 
It  should  be  observed  that  this  tendinous  roof  is  strong  over  the  lower  part  of 
the  canal,  where  it  is  pierced  by  a  branch  of  the  long  saphenous  nerve  to  the 
subsartorial  plexus,  and  by  the  arteria  anastomotica  magna.  An  endeavour 
should  be  made  at  this  stage  to  expose  the  subsartorial  plexus  as  it  lies  upon 
the  aponeurotic  covering  of  Hunter's  canal.  This  covering  should  now  be 
removed,  and  the  contents  and  boundaries  of  the  canal  exposed.  It  should 
be  observed  that  the  nerve  to  the  vastus  internus  is  only  contained  in  the 
upper  half  of  the  canal,  and  that  the  arteria  anastomotica  magna  arises  from 
the  superficial  femoral  at  the  extreme  lower  end  of  the  canal. 

The  deep  dissection  of  Scarpa's  triangle  should  now  be  undertaken.  A 
slight  interval  may  be  noted  between  the  lower  part  of  the  pectineus  and 
adductor  longus,  in  which  a  partial  view  may  be  obtained  of  the  adductor 
brevis  and  the  superficial  or  anterior  division  of  the  obturator  nerve.  The 
superficial  femoral  artery  should  be  divided  just  below  the  origin  of  the  arteria 
profunda  femoris,  as  well  as  the  femoral  vein.     The  arteria  profunda  femoris 


THE  LOWER  LIMB  563 

should  now  be  studied  as  far  as  the  upper  border  of  the  adductor  longus, 
and  this  will  be  facilitated  by  di\'iding  the  corresponding  vein.  Its  external 
circumflex  branch  should  be  followed  out  in  its  ascending,  transverse,  and 
descending  branches,  and  the  anastomoses  of  these  branches  should  be  care- 
fully studied.  An  articular  offset  to  the  hip-joint  from  the  ascending  branch 
should  be  looked  for.  The  long  descending  branch  of  this  artery  to  the 
geniculate  arterial  rete  should  be  noted. 

The  branches  of  the  anterior  or  superficial  and  posterior  or  deep  divisions 
of  the  anterior  crural  nerve  should  be  dissected,  and  the  following  articular 
nerves  should  be  looked  for,  namely,  one  to  the  hip-joint  from  the  nerve 
to  the  rectus  femoris,  and  three  to  the  knee-joint,  as  follows  :  one  from  the 
nerve  to  the  vastus  extenius  ;  one  from  the  most  internal  of  the  branches 
to  the  crureus.  supplying  in  its  course  the  subcrureus  ;  and  one  from  the 
nerve  to  the  vastus  internus,  which  ultimately  accompanies  the  deep  branch 
of  the  arteria  anastomotica  magna. 

The  vastus  externus,  crureus,  and  vastus  internus  are  next  to  be  dissected. 
The  vastus  internus  and  crureus  are  to  be  separated  by  dissecting  along  the 
course  of  a  cellular  interspace,  which  extends  upwards  in  the  direction  of 
a  line  drawn  from  the  inner  border  of  the  patella  to  the  inferior  cervical 
tubercle  of  the  femur.  When  the  vastus  internus  is  reflected  inwards,  a 
bare  strip  along  the  inner  aspect  of  the  shaft  of  the  femur,  devoid  of  muscular 
fibres,  is  to  be  noted.  The  crureus  should  next  be  turned  aside  in  two  halves 
by  making  a  vertical  incision  down  the  centre  of  the  muscle.  This  will  show 
the  lower  limit  of  origin  of  the  muscle,  and  it  will  bring  into  view  the  sub- 
crureus. The  bursa  beneath  the  suprapatellar  tendon  and  the  prolongation 
of  the  synovial  membrane  of  the  knee-joint,  wliich  is  continuous  with  it, 
should  be  shown.  In  dissecting  the  lower  part  of  the  vastus  internus  the 
deep  branch  of  the  arteria  anastomotica  magna  and  an  articular  branch  to 
the  knee-joint  from  the  nerve  to  the  vastus  internus  should  be  followed  out. 

The  pectineus  and  adductor  longus  should  be  divided  and  reflected. 
When  the  pectineus  has  been  reflected  it  should  be  noted  that  a  portion  of 
the  capsular  ligament  of  the  hip-joint  (including  the  pubo-femoral  ligament) 
is  exposed.  This  will  bring  fully  into  view  the  adductor  brevis,  with  the 
anterior  or  superficial  division  of  the  obturator  nerve  resting  upon  it,  and 
the  obturator  externus  lying  above  it.  The  continuation  of  the  arteria 
profunda  femoris  is  also  exposed.  The  four  perforating  branches  of  this 
vessel  should  be  shown,  the  first  and  second  piercing  the  adductor  brevis  and 
adductor  magnus,  whilst  the  third  and  fourth  pierce  only  the  adductor 
magnus. 

The  internal  circumflex  artery  should  be  studied  at  this  stage.  Replacing 
the  pectineus,  the  artery  should  be  traced  backwards  between  that  muscle 
and  the  psoas  magnus,  and  then  between  the  adductor  brevis  and  obturator 
externus.  In  this  latter  situation  the  artery  should  be  shown  to  divide  iiito 
its  two  terminal  branches,  namely,  {a)  ascending,  or  anterior,  passing  with 
the  obturator  externus  to  the  digital  fossa  ;  and  (6)  transverse  or  posterior, 
passing  backwards  between  the  quadratus  femoris  and  upper  border  of  the 
adductor  magnus,  and  furnishing  in  its  course  an  articular  branch  to  the 
hip-joint  which  enters  beneath  the  transverse  ligament.  It  should  be  observed 
that  the  internal  circumflex  artery  gives  branches  to  the  obturator  ex- 
ternus, which  anastomose  in  that  muscle  with  branches  of  the  obturator 
artery. 

The  adductor  brevis  should  be  divided  without  injuring  the  anterior  division 
of  the  obturator  nerve,  and  the  obturator  externus  should  be  dissected.  Its 
relation  to  the  neck  of  the  femur  and  the  capsular  ligament  should  be  noted, 
as  also  its  relation  to  the  obturator  nerve.  This  nerve  is  now  to  be  dissected. 
An  articular  l;ranch  to  the  hip-joint  from  the  anterior  division  should  be  looked 
for,  and  tlie  termination  of  tiiis  division  in  cutaneous  and  vascular  branches 
should  be  noted.  The  posterior  division  should  be  followed  out  in  the 
expectation  of  finding  it  terminating  in  the  inconstant  geniculate  branch. 
An  accessory  obturator  nerve  may  be  found  emerging  over  the  superior  pubic 
ramus  beneath  the  pectineus,  after   which    it   will  be  seen  to  end  in   three 

36—2 


564  A  MANUAL  OF  ANATOMY 

branches,  as  follows  :  one  to  the  hip-joint,  one  to  the  pectineus,  and  one  to 
reinforce  the  anterior  division  of  the  normal  obturator  nerve. 

The  obturator  externus  is  next  to  be  cut  and  reflected,  in  order  to  expose 
the  obturator  membrane  and  obturator  artery.  The  artery  should  be 
shown  to  divide  into  an  internal  and  external  branch  (the  latter  furnish- 
ing an  articular  branch  to  the  hip-joint),  and  the  arterial  loop  formed 
by  these  two  branches  at  the  circumference  of  the  obturator  membrane 
should  be  made  out.  The  anastomosis  in  the  obturator  externus  between 
the  obturator  and  internal  circumflex  arteries  will  now  be  readily  under- 
stood. The  adductor  magnus  is  next  to  be  fully  studied.  Its  division 
into  three  parts  is  to  be  shown,  as  well  as  the  four  tendinous  arches  under 
which  the  four  perforating  arteries  pass.  The  relation  of  the  muscle  to 
Hunter's  canal  is  to  be  noted,  and  the  femoral  opening  for  the  passage  of  the 
superficial  femoral  artery  and  corresponding  vein  is  to  be  dissected.  The 
dissector  should  now  replace  the  adductor  brevis,  adductor  longus,  and  pec- 
tineus, and  the  relative  positions  of  these  muscles  should  receive  attention. 
The  anterior  portions  of  the  gluteus  medius  and  gluteus  minimus  should  be 
cleaned  by  removing  the  fascia  lata,  and  when  they  are  reflected  the  bursse 
between  them  and  the  great  trochanter  should  be  shown,  as  well  as  the 
strong  arched  band  of  fibres  which  connects  the  tendon  of  the  gluteus  minimus 
with  the  upper  part  of  the  capsule  of  the  loip-joint. 

Hip- Joint. — A  careful  study  of  the  hip-joint  should  now  be  made,  pre- 
paratory to  the  removal  of  the  limb,  and  this  should  be  done  in  the  following 
order:  (i)  The  muscular  relations  of  the  capsular  ligament  should  be  care- 
fully noted,  the  muscles  not  yet  cut  should  be  divided,  the  bursa  beneath  the 
ilio-psoas  should  be  observed,  and  the  two  heads  of  the  rectus  femoris  should 
be  again  studied.  The  actions  of  the  various  muscles  upon  the  joint  should 
also  be  studied.  (2)  The  capsular  ligament  should  be  cleaned,  and  an  occa- 
sional opening  in  it  should  be  looked  for  underneath  the  ilio-psoas  bursa. 
The  various  accessory  bands  should  be  attended  to,  and  their  influence  over 
the  movements  of  the  joint  should  be  observed.  The  attachments  of  the 
capsule  to  the  femur  in  front  and  behind  are  to  be  noted,  and  the  difference 
in  direction  of  the  anterior  and  posterior  fibres,  as  well  as  their  relative  strength, 
observed.  The  effect  of  different  positions  of  the  hmb  upon  the  head  of  the 
femur  should  be  attended  to.  (3)  The  capsular  ligament  should  be  divided, 
and  the  ligaments  within  the  joint  studied,  namely,  (a)  the  cotyloid  ligament, 
(5)  the  transverse  ligament,  and  (c)  the  ligamentum  teres.  The  synovial  or 
Haversian  gland  is  also  to  be  noted.  As  regards  the  ligamentum  teres,  a 
good  plan  to  adopt  is  as  follows  :  the  dissector  of  one  limb  should  examine 
the  hip-joint  in  the  usual  manner,  namely,  from  the  front,  and  the  dissector 
of  the  other  hmb  should  avail  himself  of  this  examination.  The  dissector 
of  the  other  hmb  should  saw  through  the  upper  part  of  the  shaft  of  the  femur, 
and  leave  the  hip-joint  undisturbed  in  the  meantime.  Subsequently,  when 
the  pelvis  has  been  sufficiently  dissected,  the  dissectors  of  the  abdomen,  in 
conjunction  with  the  dissectors  of  the  lower  limbs,  should  open  into  the 
hip-joint  on  the  side  on  which  it  has  been  left  undisturbed  by  operating  upon 
the  smooth  incUned  pelvic  aspect  of  the  ischial  portion  of  the  hip-bone.  This 
dissection  will  enable  the  dissectors  to  study  the  action  of  the  ligamentum 
teres  with  the  capsular  ligament  left  undisturbed.  (4)  The  synovial  membrane 
of  the  joint  is  to  be  studied.  (5)  The  bony  articular  surfaces  are  to  be 
examined.  (6)  The  movements  at  the  joint,  and  the  muscles  by  which 
these  are  effected,  are  to  be  thoroughly  mastered,  and  the  arterial  supply  and 
nerve-supply  are  to  be  reviewed. 

The  relations  of  structures  to  the  anterior  intertrochanteric  line  should 
next  receive  attention,  and  the  obturator  canal  and  its  contents  should  be 
examined.  The  relative  position  of  the  muscles  from  the  symphysis  pubis 
outwards  to  the  obturator  foramen  should  be  noted.  Finally,  the  relative 
positions  of  the  tendons  of  insertion  of  the  sartorius,  gracilis,  and  serai- 
tendinosus,  and  the  bursa  in  connection  with  them,  should  be  examined. 

The  dissector  is  now  prepared  to  remove  the  limb.  Any  muscles  passing 
between  the  pelvis  and  the  thigh  are  to  be  cut,  and  the  ligamentum  teres  is 


THE  LOWER  LIMB  565 

to  be  divided,  after 'which  the  limb  can  be  separated.  The  tirst  duty  of 
the  dissector  is  to  trim  the  femoral  muscles,  and  revise  their  attachments 
and  relations.  On  the  inner  side  of  the  knee-joint,  if  not  previously  displayed, 
he  should  show  the  long  saphenous  vein  and  nerve,  the  posterior  division 
of  the  internal  cutaneous  nerve,  and  the  superficial  branch  of  the  arteria 
anastomotica  magna.  The  deep  branch  of  the  last-named  artery,  if  not 
previously  dissected,  should  now  be  followed  out.  The  relation  of  the  long 
external  lateral  ligament  of  the  knee-joint  to  the  tendon  of  insertion  of  the 
biceps  femoris,  as  well  as  the  bursa  in  this  situation,  and  the  expansion  from 
the  tendon  to  the  deep  fascia  of  the  leg,  should  be  shown. 

Front  and  Sides  of  the  Leg  and  Dorsum  of  the  Foot. — The  dissector  is  to  make 
himself  thoroughly  familiar  with  the  landmarks  of  the  leg  and  foot.  The  sldn  is 
then  to  be  removed  bv  making  the  following  incisions  :  a  vertical  incision  along 
the  anterior  border  of  the  tibia,  and  along  the  dorsum  of  the  foot  as  far  as  the 
web  between  the  second  and  third  toes  ;  a  transverse  incision  at  the  ankle- 
joint,  and  another  at  the  webs  of  the  toes  ;  a  median  incision  along  the  dorsum 
of  each  toe  ;  and  a  transverse  incision  across  the  dorsum  of  each  toe  close  to 
the  nail.  The  skin  is  to  be  reflected  to  either  side,  and  the  following  structures 
should  be  exposed  on  the  inner  aspect  of  the  tibia  :  ( i )  the  long  saphenous 
vein,  which  should  be  shown  passing  in  front  of  the  internal  malleolus,  and 
traced  as  far  as  the  inner  end  of  the  dorsal  venous  arch  ;  (2)  the  long  saphenous 
nerve,  accompanying  the  foregoing  vein  as  far  as  the  centre  of  the  inner  border 
of  the  foot  ;  (3)  the  posterior  division  of  the  internal  cutaneous  nerve,  ramify- 
ing in  the  integument  of  the  upper  half  of  the  leg  ;  and  (4)  the  superficial 
branch  of  the  arteria  anastomotica  magna,  ramifying  in  the  upper  third. 
Communications  are  to  be  sought  for  between  the  long  and  short  saphenous 
veins,  and  also  between  the  former  and  the  deep-seated  veins  on  the  front  of 
the  leg. 

The  venous  arch  on  the  dorsum  of  the  foot  should  next  be  displayed, 
care  being  taken  to  preserve  the  cutaneous  nerves.  The  long  saphenous  vein 
will  conduct  to  it,  and  the  small  tributary  veins  from  the  superficial  plantar 
venous  plexus  may  be  shown  turning  round  the  inner  border  of  the  foot  to 
join  the  long  saphenous  vein.  The  short  saphenous  vein  should  be  traced 
from  the  outer  end  of  the  arch  to  a  point  below  and  then  behind  the  external 
malleolus  ;  the  small  tributary  veins  from  the  superficial  plantar  venous  plexus 
ma}''  be  shown  turning  round  the  outer  border  of  the  foot  to  join  it  ;  and 
an  endeavour  may  be  made  to  show  the  following  tributaries  of  the  dorsal 
venous  arch,  namely,  (i)  the  dorsal  digital  veins;  (2)  small  veins  from  the 
dorsum  of  the  foot  ;  and  (3)  the  efferent  or  interdigital  veins  from  the  plantar 
transverse  venous  arch. 

The  dissector  should  now  display  the  musculo-cutaneous  nerve.  He  will 
find  it  piercing  the  deep  fascia  on  the  outer  side  of  the  leg  about  the  junction 
of  the  upper  two- thirds  and  lower  third.  Branches  should  be  traced  to  the 
integument  of  the  front  of  the  leg  in  its  lower  third,  and  the  main  nerve 
should  be  followed  on  in  two  divisions,  to  be  distributed  to  the  inner  side  of 
the  great  toe  and  the  contiguous  sides  of  the  second  and  third,  third  and 
fourth,  and  fourth  and  fifth  toes,  as  well  as  to  the  integument  of  the  malleoli 
and  dorsum  of  the  foot. 

The  external  or  short  saphenous  nerve  should  next  be  dissected  along  the 
outer  l;order  of  the  foot  as  far  as  the  outer  side  of  the  little  toe.  Upon  the 
outer  side  of  the  leg  the  dissector  will  find  the  lateral  cutaneous  branch  of 
the  external  poj)liteal  nerve,  which  ramifies  in  the  integument  of  about  the 
upper  two- thirds.  The  deep  fascia  of  the  front  and  sides  of  the  leg  should 
next  be  studied.  Three  intermuscular  septa  are  to  be  noted,  namely, 
anterior,  antero-external,  and  ])ostero-external.  In  the  region  of  the  ankle- 
joint  the  following  parts  of  t!ie  deep  fascia  are  to  be  specially  dissected, 
namely,  (i)  the  external  annular  ligament,  stra])pi7ig  down  the  tendons  of 
the  peroneus  longus  and  peroneus  brevis  ;  and  (2)  the  anterior  annular  liga- 
ment, which  will  be  found  in  two  divisions — one  above  the  ankle-joint  and 
the  other  in  front  of  it.  The  following  points  are  to  be  specially  noted  in 
connection  with  the  two  divisions  of  the  anterior  annular  ligament,  namely. 


566  A  MANUAL  OF  ANATOMY 

(i)  the  number  of  compartments  in  each  division  ;  (2")  the  tendons  passing 
beneath  each,  and  their  relative  position  ;  and  (3)  the  number  of  synovial 
sheaths. 

The  anterior  tibial  muscles  are  next  to  be  dissected  to  their  inser- 
tions in  the  following  order,  namely,  the  tibialis  anticus,  extensor  longus 
digitorum,  peroneus  tertius,  and  extensor  proprius  hallucis.  In  connection 
with  the  expansions  formed  by  the  long  extensor  tendons  on  the  dorsal 
aspects  of  the  metatarso-phalangeal  joints,  the  tendons  of  insertion  of 
the  lumbricales  and  interossei  are  to  be  carefully  preserved.  The  anterior 
tibial  nerve  will  be  found  coming  into  contact  with  the  outer  side  of  the  anterior 
tibial  artery  about  the  junction  of  the  upper  fourth  and  lower  three-fourths 
of  the  leg,  and  it  should  be  followed  from  this  point  as  far  as  the  front  of  the 
ankle-joint.  The  anterior  tibial  artery  is  now  to  be  shown  lying  deeply  upon 
the  interosseous  membrane  over  about  the  upper  two-thirds,  but  upon  the 
anterior  surface  of  the  tibia  in  the  lower  fourth.  In  dissecting  the  upper  part 
of  the  artery,  the  anterior  tibial  lymphatic  gland  should  be  looked  for,  and 
the  venae  comites  accompanying  the  artery  should  be  noted.  The  following 
branches  of  the  artery  should  be  shown,  namely,  anterior  tibial  recurrent, 
muscular,  internal  malleolar,  and  external  malleolar.  In  dissecting  the 
anterior  tibial  recurrent  artery,  the  recurrent  articular  branch  of  the  external 
popliteal  nerve  should  be  looked  for.  The  terminal  part  of  the  anterior 
peroneal  artery  should  be  exposed  as  it  appears  through  the  inferior  hiatus  in 
the  interosseous  membrane,  and  it  should  be  followed  downwards  under  cover 
of  the  peroneus  tertius  and  in  front  of  the  inferior  tibio-fibular  articulation, 
to  take  part  in  the  external  malleolar  anastomosis. 

The  dissector  should  now  turn  his  attention  to  the  dorsum  of  the  foot. 
The  deep  fascia  should  be  examined.  The  extensor  brevis  digitorum  is  to  be 
dissected,  and  the  insertion  of  its  innermost  tendon  and  its  relation  to  the 
arteria  dorsalis  pedis  are  to  be  noted.  The  arteria  dorsalis  pedis  and  its  venae 
comites  are  to  be  dissected,  and  the  following  branches  of  the  artery  are  to 
be  followed  out,  namely,  internal  tarsal,  external  tarsal,  metatarsal,  and 
arteria  dorsalis  hallucis.  The  arch  formed  by  the  metatarsal  branch  is  to  be 
noted,  and  three  dorsal  interosseous  arteries  are  to  be  dissected  forwards  from 
it.  The  dorsalis  pedis  nerve  (the  continuation  of  the  anterior  tibial  nerve)  is 
next  to  be  dissected  as  far  as  the  cleft  between  the  great  toe  and  second, 
where  it  will  be  found  to  divide  into  two  collateral  dorsal  digital  branches  for 
the  supply  of  the  contiguous  sides  of  these  two  toes.  The  offset  which  it 
receives  from  the  branch  of  the  musculo-cutaneous  nerve  to  the  inner  side  of 
the  great  toe  is  to  be  shown,  and  the  external  branch  of  the  nerve  is  to  be 
followed  beneath  the  extensor  brevis  digitorum.  In  this  situation  its  gangli- 
form  enlargement  is  to  be  looked  for,  and  the  offsets  arising  therefrom  may 
be  followed  out. 

The  four  dorsal  interosseous  muscles  should  now  be  dissected.  In  connec- 
tion with  the  first  dorsal  interosseous  the  plantar  or  perforating  branch  of 
the  arteria  dorsalis  pedis  is  to  be  noted,  and  in  connection  with  the  second, 
tliird,  and  fourth,  the  posterior  and  anterior  perforating  arteries  should  be 
looked  for. 

The  dissector  should  now  turn  his  attention  to  the  external  aspect  of  the 
leg,  where  the  peroneus  longus  and  peroneus  brevis  are  to  be  dissected. 
The  latter  muscle  should  be  dissected  throughout  its  entire  course,  but  the 
former  should  only  be  followed  meanwhile  as  far  as  the  groove  on  the  outer 
border  of  the  cuboid  bone.  In  dissecting  these  muscles,  the  fibro-osseous 
tunnel  in  which  they  lie  is  to  be  noted.  The  musculo-cutaneous  and  anterior 
tibial  nerves  are  now  to  be  traced  upwards  to  their  origin  from  the  external 
popliteal  at  the  level  of  the  neck  of  the  fibula.  In  doing  so,  in  the  case  of  the 
musculo-cutaneous  nerve,  both  peroneal  muscles  are  to  be  cut  in  so  far  as  may 
be  necessary,  and  in  the  case  of  the  anterior  tibial  nerve  the  extensor  longus 
digitorum  and  peroneus  longus  are  to  be  cut.  The  mode  of  ending  of  the 
external  popliteal  nerve  will  now  be  made  manifest,  its  terminal  branches 
being  the  anterior  tibial,  musculo-cutaneous,  and  recurrent  articular. 

Back  of  the  Leg. — A  transverse  incision  having  been  made  over  the  heel,  the 


THE  LOWER  LIMB  567 

skin  is  to  be  reflected  from  the  back  of  the  leg.  The  terminal  distribution 
of  the  small  sciatic  ner\'e  having  been  revised,  the  dissector  should  trace  the 
ramus  communicans  tibialis  and  ramus  communicans  tibularis  nerves  to  the 
centre  of  the  calf,  the  former  lying  in  the  median  groove  of  the  gastrocnemius, 
and  the  latter  descending  obliquely  inwards  over  the  outer  head  of  that 
muscle.  At  or  about  the  centre  of  the  calf  these  two  nerves  will  usually  be 
found  to  unite,  and  so  form  the  external  or  short  saphenous  nerve.  This 
nerve,  along  with  the  short  saphenous  vein,  should  be  followed  superficial  to 
the  deep  fascia  downwards  and  outwards  along  the  outer  side  of  the  tendo 
AchiUis  (the  nerve  meanwhile  giving  branches  to  the  integument  of  the  lower 
half  of  the  back  of  the  leg),  then  behind  and  below  the  external  malleolus  (in 
which  situation  the  nerve  supphes  calcaneal  and  malleolar  branches),  and 
subsequently  along  the  outer  border  of  the  foot.  Communications  between 
the  short  saphenous  vein  and  the  long  saphenous  vein  are  to  be  sought  for. 
as  well  as  communications  between  the  former  and  the  deeply-seated  veins 
which  accompany  the  posterior  tibial  and  peroneal  arteries. 

The  deep  fascia  of  the  back  of  the  leg  is  next  to  be  dissected,  and  thereafter 
the  gastrocnemius  muscle  is  to  be  studied.  The  inner  head  of  the  muscle 
having  been  previously  cut  in  connection  with  the  dissection  of  the  lower  part 
of  the  pophteal  space, ^the  outer  head  is  now  to  be  divided,  and  both  heads  are 
to  be  reflected  upwards  in  order  to  show  the  exact  origin  of  each,  that  of  the 
inner  head  lying  obliquely,  whilst  that  of  the  outer  head  lies  vertically.  The 
pophteal  bursa,  which  separates  the  inner  head  from  the  semimembranosus, 
should  be  sought  for,  and  its  relation  to  the  synovial  membrane  of  the 
knee  -  joint  examined.  In  the  outer  head  of  the  muscle  will  be  found  a 
sesamoid  fibro-cartilage  (sometimes  ossified).  The  belly  of  the  gastrocnemius 
and  its  tendon  is  to  be  reflected  downwards  as  far  as  the  commencement  of 
the  tendo  AchiUis.  The  plantaris  is  then  to  be  dissected,  and  its  long, 
narrow  tendon  should  be  taken  between  the  index-finger  and  thumb  of  each 
hand  and  stretched  laterally  to  demonstrate  its  distensibiUty.  The  soleus 
is  next  to  be  dissected,  and  the  fibrous  arch  over  the  posterior  tibial  vessels 
is  to  be  shown,  with  fibres  of  the  muscle  springing  from  it.  A  branch  from 
the  internal  pophteal  nerve  is  to  be  found  entering  the  superficial  surface  of 
the  muscle  near  its  upper  border.  The  other  nerve-supply  from  the  posterior 
tibial  will  only  come  into  view  as  the  muscle  is  being  reflected.  The  tendon 
of  the  soleus  is  to  Ije  shown  joining  that  of  the  gastrocnemius  to  form  the 
tendo  AchiUis.  The  aponeurotic  appearance  presented  by  the  deep  surface 
of  the  gastrocnemius  and  the  superficial  surface  of  the  soleus  is  to  be  noted. 
The  tendo  AchiUis  is  to  receive  careful  attention. 

Before  the  soleus  is  disturbed,  the  hollow  on  either  side  of  the  tendo  AchiUis 
is  to  be  noted.  In  the  outer  hollow  the  short  saphenous  vein  and  nerve 
have  been  already  dissected,  their  position  being  here  superficial.  Lying 
deeply  in  the  hollow  on  the  inner  side  of  the  tendon  are  the  posterior  tibial 
vessels  and  nerve.  A  Umited  opening  should  be  made  in  the  deep  fascia  to 
show  the  exact  position  and  relations  of  these  structures.  The  soleus  is  now 
to  be  stripped  from  its  tibial  and  fibular  origins  and  turned  downwards.  In 
the  course  of  this  dissection  a  branch  from  the  posterior  tibial  nerve  is  to  be 
shown  entering  the  deep  surface  of  the  muscle  about  the  centre  of  the  leg. 
The  tendo  AchiUis  having  been  turned  downwards,  the  large  quantity  of  fat 
beneath  it  is  to  Ije  observed,  and  the  bursa  between  the  tendon  and  the  upper 
zone  of  the  posterior  surface  of  the  tuber  calcis  is  to  be  shown.  By  dissecting 
into  the  deep  surface  of  the  soleus,  the  arrangement  of  its  very  short  fibres 
will  be  brought  into  view. 

The  lower  part  of  the  jjopliteal  vessels  and  interned  popliteal  nerve,  though 
previously  dissected,  should  now  be  revised.  The  division  of  the  artery  into 
anterior  tibial  and  posterior  tibial  at  the  lower  border  of  the  jiopliteus  muscle 
should  be  noted.  The  commencement  of  the  anterior  tibial  artery  is  to  be 
dissected,  showing  the  vessel  passing  forwards  between  the  two  heads  of  the 
tibialis  posticus,  and  between  the  tibia  and  fibula.  Its  branches  in  this  situa- 
tion are  to  be  shown,  namely,  posterior  tibial  recurrent  (inconstant),  and 
superior  fibular.     The  nerve  to  the  popliteus  from  the  internal  popliteal,  if 


568  A  MANUAL  OF  ANATOMY 

not- previously  dissected,  is  to  be  followed  out.  The  inferior  external  and 
inferior  internal  articular  arteries  are  to  be  studied.  The  popliteal  fascia 
covering  the  popliteus  muscle  is  to  be  inspected,  noting  that  it  is  one  of  the 
modes  of  insertion  of  the  semimembranosus.  The  fascia  is  now  to  be  removed, 
in  doing  which  it  should  be  noted  that  the  superficial  fibres  of  the  popliteus 
muscle  take  insertion  into  its  deep  surface.  In  the  meantime,  the  exact  origin 
of  that  muscle  cannot  be  shown,  so  that  the  dissector  should  content  himself 
with  showing  the  tendon  after  its  escape  from  the  interior  of  the  knee-joint, 
when  it  is  almost  immediately  replaced  by  fleshy  fibres. 

The  sural  muscles  having  been  completely  turned  aside,  the  expansion  of  the 
deep  fascia,  called  the  posterior  or  transverse  intermuscular  septum,  is  to  be 
studied.  In  connection  with  it  the  internal  annular  ligament  is  to  be  dis- 
played (but  not  opened  up  as  yet)  between  the  internal  malleolus  and  the 
tuber  calcis.  In  doing  so,  care  must  be  taken  to  preserve  the  calcaneo-plantar 
branch  of  the  posterior  tibial  nerve  and  the  internal  calcaneal  branch  of  the 
posterior  tibial  artery,  both  of  which  pierce  the  Ugament.  The  deep  muscles 
of  the  back  of  the  leg  are  to  be  cleaned,  and  at  the  same  time  the  posterior 
tibial  vessels  and  nerve  are  to  be  dissected.  The  muscles  from  within  outwards 
are  the  flexor  longus  digitorum,  tibialis  posticus,  and  flexor  longus  hallucis. 
It  should  be  observed  that  the  tibialis  posticus  is  covered  superficially  by  a 
strong  aponeurotic  expansion,  which  stretches  across  between  the  muscles  on 
either  side  of  it.  In  dissecting  the  lower  portions  of  these  muscles  in  the 
neighbourhood  of  the  ankle-joint,  the  internal  annular  ligament  is  now  to  be 
opened,  when  it  will  be  seen  to  contain  four  canals,  three  of  which  are  fibro- 
osseous,  and  one  (for  the  flexor  longus  digitorum)  purely  fibrous.  The  relation 
of  the  tendons,  posterior  tibial  vessels,  and  posterior  tibial  nerve  as  they  traverse 
these  canals  is  to  be  studied,  and  the  synovial  sheaths  are  to  be  noted.  The 
branches  of  the  posterior  tibial  artery  and  nerve  are  to  be  displayed.  As 
regards  the  branches  of  the  artery,  they  should  be  dissected  in  the  following 
order  from  above  downwards,  namely,  (i)  peroneal,  of  large  size,  and 
arising  about  i  inch  below  the  commencement  of  the  posterior  tibial  ; 
(2)  medullary,  for  the  tibia  (of  large  size)  ;  (3)  muscular  ;  (4)  communicating 
or  transverse,  near  the  ankle,  and  passing  transversely  outwards  to  join  a 
similar  branch  of  the  peroneal  ;  (5)  internal  malleolar,  usually  two  in  number, 
and  passing  beneath  the  tendons  behind  the  internal  malleolus  to  take  part 
in  the  internal  malleolar  anastomosis  ;  (6)  internal  calcaneal  ;  and  (7)  the  two 
terminal  branches,  internal  and  external  plantar  arteries.  Two  venae  comites 
are  to  be  dissected  with  the  posterior  tibial  artery,  which  communicate  at 
frequent  intervals  by  transverse  branches  placed  superficial  to  the  vessel. 
These  venae  comites  should  be  shown  to  join  those  of  the  anterior  tibial  artery 
at  the  lower  border  of  the  popliteus  muscle,  and  so  form  the  popliteal  vein. 
The  peroneal  branch  of  the  posterior  tibial  artery  requires  special  dissection. 
After  reaching  the  back  of  the  fibula,  it  sinks  deeply  and  disappears  from  view, 
its  course  being  either  between  the  fibula  and  the  flexor  longus  hallucis,  or 
in  that  muscle,  or  in  a  fibrous  canal  between  that  muscle  and  the  tibialis 
posticus.  It  will  next  be  found  becoming  superficial  about  2  inches  above 
the  ankle,  where  it  should  be  shown  to  end  by  dividing  into  an  anterior  and 
a  posterior  peroneal  branch.  Two  venae  comites  are  to  be  dissected  with  the 
peroneal  artery,  which  end  by  joining  those  of  the  posterior  tibial.  The 
following  branches  of  the  peroneal  artery  are  to  be  dissected  from  above 
downwards,  namely,  (i)  muscular;  (2)  medullary  to  fibula;  (3)  communi- 
cating or  transverse  ;  (4)  anterior  peroneal,  disappearing  through  the  inferior 
hiatus  in  the  interosseous  membrane  ;  and  (5)  posterior  peroneal.  The  last- 
named  artery  is  to  be  shown  passing  behind  the  external  malleolus  on  to  the 
outer  border  of  the  foot  for  a  variable  distance.  It  will  be  seen  to  give  off 
external  calcaneal  branches,  which  take  part  in  the  external  malleolar  anasto- 
mosis, and  anastomose  across  the  heel  with  the  internal  calcaneal  branches 
of  the  external  plantar.  On  the  outer  border  of  the  foot  it  will  be  seen  again 
to  anastomose  with  branches  of  the  external  plantar. 

Knee-Joint. — The  knee-joint  is  to  be  dissected  before  proceeding  with  the 
sole  of  the  foot.     The  muscular  and  tendinous  relations  of  the  joint  are  to  be 


THE  LOWER  LIMB  569 

studied,  and  the  threefold  insertion  of  the  semimembranosus  is  to  be  displayed. 
The  arteries  entering  into  the  geniculate  arterial  rete  are  to  be  studied  as  fully 
as  possible.  All  the  external  ligaments  of  the  joint  are  now  to  be  dissected, 
namely,  (i)  the  ligamentum  patellas  ;  (2)  the  lateral  patellar  Hgaments  ; 
(3)  the  internal  lateral  ligament,  -with  the  inferior  internal  articular  artery 
passing  beneath  it,  and  the  maiir  division  of  the  tendon  of  the  semimem- 
branosus overlapped  by  it  posteriorly  ;  (4)  the  long  and  short  external  lateral 
ligaments,  \\'ith  the  inferior  external  articular  artery  passing  beneath  the 
long  ligament  ;  (5)  the  posterior  lig:ament,  with  its  thickened  part,  known  as 
the  ligamentum  posticum  Winslowdi ;  and  (6)  the  capsular  ligament.  In  con- 
nection with  the  ligamentum  patellae,  the  bursa  between  it  and  the  upper 
part  of  the  tubercle  of  the  tibia  should  be  shown.  The  exact  origin  of  the 
tendon  of  the  popliteus  is  to  be  displayed,  and  its  relation  to  the  joint  and  the 
long  external  lateral  ligament  noted.  The  expansion  of  the  synovial  mem- 
brane of  the  joint  upwards  above  the  patella  and  beneath  the  suprapatellar 
tendon  is  to  be  again  studied.  The  articulation  is  now  to  be  opened  from 
before  by  cutting  transversely  down  through  the  synovial  membrane  just 
above  the  patella.  This  bone,  along  with  the  ligamentum  patellae,  having 
been  turned  downwards,  underneath  them  will  be  seen  a  collection  of  fat 
covered  by  the  synovial  membrane,  and  representing  the  Haversian  gland 
of  the  joint.  In  connection  with  this  portion  of  the  synovial  membrane,  the 
following  so-called  hgaments  are  to  be  studied,  namely,  the  Hgamentum 
mucosum  and  the  ligamenta  alaria.  The  crucial  ligaments  are  next  to  be 
examined  in  situ,  as  well  as  the  semilunar  fibro-cartilages. 

The  synovial  membrane  is  to  be  examined,  and  thereafter  the  following 
external  ligaments,  are  to  be  cut,  namely,  the  capsular  and  the  posterior, 
thus  leaving  only  the  two  lateral  ligaments  intact.  The  joint  is  now  to  be 
placed  in  different  positions — e.g.,  flexion,  extension,  internal  rotation,  and 
external  rotation — and  the  conditions  of  the  crucial  and  lateral  ligaments, 
as  well  as  of  the  semilunar  fibro-cartilages,  are  to  be  carefully  attended  to. 

The  lateral  ligaments  are  then  to  be  cut,  when  the  femur  will  be  bound  to  the 
tibia  only  by  the  crucial  ligaments,  which  should  be  completely  mastered.  The 
femur  should  be  firmly  grasped  and  the  tibia  rotated  inwards  in  order  to  see 
the  effect  of  this  upon  the  anterior  crucial  ligament.  The  tibia  should  next 
be  rotated  outwards,  and  it  will  then  l)e  made  to  describe  half  a  circle,  neither 
crucial  ligament  interfering  with  this  movement.  In  connection  with  the 
posterior  cornu  of  the  external  semilunar  fibro-cartilage,  the  posterior  acces- 
sory bundle  is  to  be  observed,  and  thereafter  the  crucial  ligaments  are  to  be 
divided.  The  upper  surface  of  the  head  of  the  tibia  being  now  fully  exposed, 
the  semilunar  fibro-cartilages  are  to  be  studied,  and  in  connection  with  their 
anterior  aspects  the  transverse  ligament  is  to  be  examined.  Lastly,  the  bony 
articular  surfaces  are  to  be  examined. 

Sole  ol  the  Foot. — The  skin  is  to  be  removed  from  the  sole  and  plantar  aspects 
of  the  toes  by  making  the  following  incisions  :  a  median  incision  from  the 
heel  to  the  roots  of  the  toes,  a  transverse  incision  across  the  roots  of  the  toes, 
a  median  incision  along  the  plantar  aspect  of  each  toe,  and  a  transverse 
incision  across  the  tip  of  each  toe.  Within  the  skin  of  the  webs  of  the  toes 
a  bundle  of  transverse  fibres,  called  the  superficial  transverse  ligament,  is 
to  be  dissected.  The  sujierficial  fascia  should  be  examined,  and  the  calcaneal 
and  plantar  divisions  of  the  calcaneo-plantar  branch  of  tlie  posterior  tibial 
nerve  are  to  be  followed  out  to  their  distribution. 

The  superficial  fascia  is  now  to  be  removed  so  as  to  expose  the  dense  deep 
fascia,  known  as  the  plantar  fascia.  In  dissecting  the  three  divisions  of  this 
important  fascia,  care  is  to  Ijc  taken  to  display  the  following  structures  :  (i) 
cutaneous  branches  of  tlie  internal  plantar  artery  and  nerve,  which  appear  in 
the  groove  between  the  inner  and  middle  divisions  ;  and  (2)  cutaneous  branches 
of  the  external  plantar  artery  and  nerve,  which  aj)j)ear  in  the  groove  between 
the  middle  and  outer  divisions.  The  three  divisions  of  the  fascia  are 
then  to  be  carefully  studied,  and  the  grooves  between  them,  indicating 
intermuscular  septa,  are  to  be  noted.  In  the  outer  groove,  near  the  base  of 
the  fifth  metatarsal    bone,   the  external  plantar  artery  should  be  exposed, 


570  A   MANUAL  OF  ANATOMY 

and  its  superficial  position  noted.  Special  attention  is  to  be  directed  to  the 
middle  division  of  the  fascia.  On  being  followed  towards  the  toes,  it 
should  be  shown  to  divide  into  five  digital  processes,  one  for  each  toe.  The 
longitudinal  direction  of  the  fibres  (from  heel  to  toes)  should  be  observed,  but 
towards  the  toes  superadded  transverse  fibres  are  to  be  displayed.  In  the 
interval  between  the  diverging  digital  processes  the  plantar  digital  vessels 
and  nerves  are  to  be  sought  for  and  followed  along  the  sides  of  the  toes.  The 
manner  in  which  the  digital  processes  are  disposed  is  to  be  studied,  and  the 
bearing  of  the  middle  division  of  the  plantar  fascia  upon  the  deformity- 
known  as  pes  cavus  is  to  be  carefully  noted.  In  connection  with  the  outer 
division  of  the  fascia  attention  should  be  paid  to  the  strong  band  which 
passes  between  the  outer  tubercle  of  the  os  calcis  and  the  tuberosity  on  the 
outer  side  of  the  base  of  the  fifth  metatarsal  bone,  and  which  may  be 
represented  by  a  muscle  known  as  the  abductor  ossis  metatarsi  quinti  or 
Wood's  nruscle. 

The  plantar  fascia  is  now  to  be  removed  in  the  following  manner  : 
(i)  the  thin  inner  division  is  to  be  removed  in  the  ordinary  way  so  as  to 
expose  the  abductor  hallucis  muscle,  which  it  covers  ;  (2)  the  stronger  outer 
division  is  also  to  be  removed  in  the  usual  way  so  as  to  expose  the  abductor 
minimi  digiti,  which  lies  underneath  it  ;  (3)  the  very  strong  middle  division, 
which  closely  covers  the  flexor  brevis  digitorum,  is  to  be  carefully  divided 
transversely  about  i  inch  in  front  of  the  heel,  the  posterior  narrow  part  is  to 
be  dissected  backwards,  and  the  expanding  anterior  part  is  to  be  reflected  for- 
wards. This  dissection  will  bring  into  view  the  flexor  brevis  digitorum,  and  it 
will  show  the  extent  to  which  the  superficial  fibres  of  that  muscle  take  origin 
from  the  deep  surface  of  the  middle  division  of  the  fascia.  In  dissecting  the 
tendon  of  insertion  of  the  abductor  hallucis,  the  inner  head  of  the  flexor  brevis 
hallucis  is  to  be  shown  joining  it,  and  a  branch  from  the  internal  plantar  nerve 
is  to  be  looked  for  entering  the  abductor  hallucis  on  its  deep  aspect  about  the 
centre.  In  dissecting  the  flexor  brevis  digitorum,  it  should  be  shown  to  end 
in  four  tendons  for  the  four  outer  toes.  Each  tendon  will  be  found  to  lie 
superficial  to  a  tendon  of  the  long  flexor  of  the  toes,  and  the  canal  in  which 
each  pair  of  tendons  lies  before  passing  along  the  toes  should  be  studied. 

The  sheaths  which  confine  the  flexor  tendons  as  they  pass  along  the  plantar 
aspects  of  the  toes  are  next  to  be  dissected.  Upon  one  or  more  toes  the 
sheaths  are  to  be  laid  open,  the  insertions  of  the  tendons  made  out,  and  the 
vincula  accessoria  tendinum  (ligamenta  longa  and  ligamenta  brevia)  shown. 
A  similar  dissection  is  to  be  made  in  connection  with  the  tendon  of  the  flexor 
longus  hallucis.  The  intermuscular  septum  on  either  side  of  the  short  flexor 
is  to  be  noted,  and  twigs  from  the  internal  plantar  nerve  are  to  be  looked  for 
entering  the  muscle  on  its  deep  surface.  In  dissecting  the  abductor  minimi 
digiti,  twigs  from  the  external  plantar  nerve  are  to  be  looked  for  entering  the 
deep  surface  of  the  muscle  at  its  back  part. 

The  muscles  of  the  flrst  layer  are  to  be  divided  near  their  origins  and 
thrown  forwards.  The  tendons  of  the  flexor  longus  digitorum  and  flexor 
longus  hallucis  are  now  to  be  dissected,  the  former  passing  forwards  and 
outwards,  and  the  latter  forwards  and  inwards.  The  crossing  between 
these  two  tendons  should  be  noted,  that  of  the  flexor  longus  hallucis 
being  uppermost,  and  the  slip  which  this  tendon  furnishes  to  that  of 
the  long  flexor  of  the  toes  should  be  displayed.  The  tendon  of  the  flexor 
longus  hallucis  is  to  be  followed  out  to  its  insertion,  and  the  vincula  accessoria 
tendinum  shown  within  its  sheath  on  the  great  toe.  The  flexor  or  musculus 
accessorius  is  to  be  dissected  in  connection  with  the  tendon  of  the  long  flexor 
of  the  toes  previous  to  its  division.  In  dissecting  the  musculus  accessorius 
the  external  plantar  vessels  and  nerve  are  to  be  carefully  preserved  as  they 
cross  the  sole,  and  twigs  of  the  nerve  are  to  be  looked  for  entering  the  inferior 
surface  of  the  muscle  at  its  back  part.  The  four  lumbricales  muscles  are  to  be 
dissected  in  connection  with  the  four  tendons  of  the  long  flexor  of  the  toes. 
It  should  be  noted  that  the  innermost  lumbricalis  arises  only  from  one  tendon, 
whilst  the  other  three  arise  each  from  the  contiguous  sides  of  two  tendons. 
A  branch  from  the  second  digital  nerve  of  the  internal  plantar  should  be  shown 


THE  LOWER  LIMB  571 

entering  the  innermost  lumbricalis,  whilst  the  other  three  will  be  found  to 
receive  their  nerve-supply  from  the  deep  part  of  the  external  plantar  nerve. 

The  internal  plantar  nerve  is  now  to  be  dissected,  as  well  as  the  internal 
plantar  artery.  The  small  size  of  the  artery  and  the  large  size  of  the  nerve 
are  to  be  noted,  and  each  is  to  be  followed  out  to  its  distribution.  The 
external  plantar  artery  and  nerve  are  next  to  be  dissected  in  the  first  part 
of  their  course  as  they  cross  the  sole  from  within  outwards.  The  large  size 
of  the  artery  is  to  be  noted,  and  the  nerve  is  to  be  shown  supplying  the  mus- 
culus  accessorius  and  abductor  minimi  digiti,  besides  giving  off  articular  and 
cutaneous  branches.  The  superficial  terminal  branch  of  the  e.xternal  plantar 
nerve  is  also  to  be  followed  out,  showing  its  two  digital  nerves,  the  outer- 
most of  which  supplies  the  flexor  brevis  minimi  digiti,  and,  as  a  rule,  the 
interosseous  muscles  of  the  fourth  space.  The  tendons  of  the  flexor  longus 
hallucis  and  flexor  longus  digitorum  and  the  musculus  accessorius  are  now 
to  be  divided  near  the  ankle  and  turned  forwards,  but  the  plantar  vessels 
and  nerves  are  to  be  left  undisturbed. 

The  dissector  is  then  to  display  the  third  layer  of  muscles  in  the  following 
order  from  within  outwards  ;  flexor  brevis  hallucis,  adductor  obliquus  hallucis, 
and  flexor  brevis  minimi  digiti.  Lying  across  the  heads  of  the  four  outer 
metatarsal  bones  will  be  found  the  adductor  transversus  hallucis  (transver- 
salis  pedis).  In  dissecting  the  flexor  brevis  hallucis  its  single  origin  and  double 
insertion  are  to  be  noted,  and  a  sesamoid  bone  is  to  be  looked  for  in  each  head 
of  insertion.  Its  nerve  is  to  be  found  coming  from  the  first  or  most  internal 
digital  branch  of  the  internal  plantar.  The  nerve  of  the  adductor  obliquus 
hallucis  is  to  be  found  coming  from  the  deep  part  of  the  external  plantar  nerve. 
In  dissecting  the  flexor  brevis  minimi  digiti  care  must  be  taken  to  separate 
It  from  the  most  external  plantar  interosseous,  close  to  which  it  lies,  and  with 
which  it  is  apt  to  be  confounded.  Its  nerve  is  usually  to  be  found  coming 
from  the  outer  digital  branch  of  the  superficial  part  of  the  external  plantar. 
In  dissecting  the  adductor  transversus  hallucis  it  should  be  noted  that  the 
digital  nerves  on  their  way  to  the  toes  lie  superficial  to  the  muscle,  whilst 
the  digital  vessels  lie  on  its  deep  surface.  The  nerve-supply  of  this  muscle  is 
to  be  found  coming  from  the  deep  part  of  the  external  plantar.  The  dissector 
should  now  show  the  relation  of  muscles  which  take  insertion  into  the  base 
of  the  first  phalanx  of  the  great  toe,  as  follows:  inner  side — abductor  hallucis 
and  inner  head  of  flexor  brevis  hallucis  ;  outer  side — outer  head  of  flexor 
Ijrevis  hallucis,  adductor  oblicjuus  hallucis,  and  adductor  transversus  hallucis. 
The  plantar  triangle  and  its  contents  should  next  he  examined. 

The  further  stage  of  the  dissection  of  the  sole  consists  in  dividing  the 
flexor  brevis  hallucis  and  adductor  obliquus  hallucis,  in  order  to  expose 
(i)  the  deep  parts  of  the  external  plantar  artery  and  nerve,  (2)  the  plantar 
(and  dorsal)  interossei  muscles,  and  (3)  the  plantar  or  perforating  branch  of 
the  arteria  dorsalis  pedis.  In  the  case  of  the  deep  part  of  the  external  plantar 
nerve,  muscular,  articular,  and  perforating  branches  are  to  be  looked  for.  It 
is  to  be  noted  that  the  deep  part  of  the  external  plantar  nerve  gives  l)ranches 
to  the  outer  three  lum])ricales.  In  the  case  of  the  deep  part  of  the  external 
plantar  artery  the  plantar  arch  and  its  branches  are  to  be  dis.sected.  The 
plantar  or  perforating  branch  of  the  arteria  dorsalis  pedis  is  to  be  found 
appearing  at  the  proximal  part  of  the  first  interosseous  space,  and  the  following 
branches  are  to  be  dissected,  namely,  arteria  magna  or  princeps  hallucis,  and 
communicating  to  the  plantar  arch. 

The  external  plantar  artery  and  nerve  may  now  be  cut  to  enable  them  to 
be  laid  fully  aside,  and  the  ])lantar  intero.sseous  mu.scles  are  to  be  dissected. 
Care  must  ha  taken  not  to  confound  the  most  external  plantar  interosseous 
with  the  flexor  brevis  minimi  digiti.  At  this  stage  of  the  dissection  the  inser- 
tion of  the  lumbricales  is  to  be  studied.  The  innervation  of  the  interossei  will 
be  found  to  come  from  the  deej)  part  of  the  external  jjJantar  nerve,  except  in 
the  case  of  the  interossei  of  the  fourth  space,  which  usually  get  their  nerve- 
supply  from  the  outer  digital  branch  of  the  superficial  j)art  of  the  external 
plantar.  The  dissector  should  now  revise  the  insertion  of  ciU  the  tendons 
connected  with  the  foot,  and,  if  any  have  not  yet  been  followed  out  to  their 


572  A  MANUAL  OF  ANATOMY 

insertions,  this  should  now  be  done.  The  actions  of  the  muscles  to  which 
these  tendons  give  insertion  should  be  mastered,  with  special  reference  to  the 
different  varieties  of  club-foot,  and  an  articulated  foot  should  be  before  the 
dissector  to  enable  him  to  illustrate  these  varieties  and  the  actions  of  the 
muscles  involved  in  producing  them. 

Attention  is  now  to  be  directed  to  the  remaining  articulations,  namely, 
the  tibio-fibular  joints,  the  ankle-joint,  and  the  joints  of  the  foot.  Before 
removing  the  muscles  of  the  front  of  the  leg  and  the  deep  muscles  of  the 
back,  the  anterior  and  posterior  relations  of  the  interosseous  membrane 
should  be  studied,  and  the  rauscular  relations  of  the  ankle-joint  mastered. 
Thereafter  the  muscles  are  to  be  removed,  and  attention  is  to  be  directed 
first  to  the  superior  tibio-fibular  joint.  The  relation  of  the  tendon  of  insertion 
of  the  biceps  femoris  to  the  joint  is  to  be  noted,  as  well  as  the  relation  of  the 
tendon  of  the  popliteus.  More  especially,  the  relation  of  the  anterior  division 
of  the  biceps  tendon  to  the  anterior  hgament  of  the  joint  is  to  be  studied. 
Having  dissected  the  ligaments  (anterior  and  posterior),  the  joint  is  to  be 
opened  and  the  synovial  membrane  examined.  The  bony  articular  surfaces 
are  also  to  be  inspected,  and  the  movements  of  which  the  joint  is  capable  are  to 
be  studied.  The  interosseous  membrane  is  next  to  be  dissected.  The  large 
deficiency  left  at  its  upper  part  for  the  passage  of  the  anterior  tibial  vessels 
and  lymphatics  is  to  be  noted,  and  the  anterior  tibial  lymphatic  gland,  if  not 
previously  dissected,  is  now  to  be  shown.  In  the  lower  part  of  the  interosseous 
membrane  a  small  opening  is  to  be  displayed  for  the  passage  of  the  anterior 
peroneal  vessels.  The  inferior  tibio-fibular  joint  is  next  to  be  examined, 
pursuing  the  same  order  as  in  the  examination  of  the  superior.  The  ligaments 
to  be  dissected  are  anterior,  posterior,  inferior  interosseous,  and  transverse, 
special  attention  being  directed  to  the  inferior  interosseous  ligament.  The 
joint  having  been  opened,  the  synovial  membrane  (which  is  continuous  with 
that  of  the  ankle-joint)  is  to  be  examined.  Attention  should  next  be  directed 
to  the  bony  articular  surfaces  and  the  movements  of  which  the  joint  is  capable. 

The  ankle-joint  should  now  be  carefully  examined.  The  dissector  should 
first  revise  the  muscular  relations  of  the  joint,  and  thereafter  he  should 
dissect  the  following  ligaments  :  anterior,  posterior,  internal  lateral  or  del- 
toid, and  external  lateral  in  three  fasciculi,  anterior,  middle,  and  posterior. 
The  anterior  and  posterior  Ugaments  are  then  to  be  cut  and  the  synovial  mem- 
brane examined.  Its  continuity  with  the  synovial  membrane  of  the  inferior 
tibio-fibular  joint  is  to  be  noted,  and  collections  of  fat  covered  by  it  (Haversian 
glands)  are  to  be  shown  at  the  front  and  back  of  the  joint.  The  bony  articular 
surfaces  are  to  be  examined,  and  special  attention  is  to  be  given  to  the  move- 
ments of  which  the  joint  is  capable,  and  the  muscles  by  which  these  are  effected. 

The  longitudinal  and  transverse  arches  of  the  foot  should  now  receive  careful 
attention,  and  a  review  of  the  different  varieties  of  club-foot  and  the  tendons 
involved  will  prove  advantageous.  Thereafter  the  articulations  of  the  foot 
are  to  be  dissected,  and  in  doing  so  it  is  advisable  that  the  dissector  should 
have  before  him  an  articulated  foot  and  the  individual  bones,  all  belonging 
to  the  same  side  as  that  which  he  is  dissecting.  The  tarsal  articulations  are 
to  be  studied  first,  in  the  following  order:  (i)  astragalo  -  calcaneal ;  (2) 
astragalo-navicular  ;  (3)  calcaneo-cuboid  ;  (4)  naviculo-cuboid  ;  (5)  naviculo- 
cuneiform  ;  (6)  intercuneiform  ;  and  (7)  cubo-cuneiform.  Before  pursuing 
this  order  the  dissector  should  make  himself  familiar  with  the  transverse 
tarsal  articulation — that  is  to  say,  the  conjoined  astragalo-navicular  and 
calcaneo-cuboid  joints,  where  disarticulation  is  performed  in  Chopart's 
operatioii.  He  should  also  study  the  expansions  from  the  tendon  of  insertion 
of  the  tibialis  posticus,  and  he  should  at  this  stage  revise  the  tendon  of  the 
peroneus  longus  as  it  crosses  the  sole  of  the  foot.  In  connection  with  the 
astragalo-calcaneal  articulation  two  joints  are  to  be  recognised — posterior 
and  anterior.  The  following  ligaments  are  to  be  studied  in  connection  with 
the  posterior  joint  :  interosseous,  posterior,  internal,  and  external.  Only 
a  lateral  view  of  the  interosseous  ligament  will  be  obtained  at  this  stage, 
as  it  lies  in  the  sinus  pedis.  It  is  to  be  noted  that  this  joint  has  a  synovial 
membrane  peculiar  to  it.     The  anterior  astragalo-calcaneal  joint  is  next  to 


THE  LOWER  LIMB 


573 


be  dissected,  and  the  following  ligaments  studied  :  interosseous,  internal 
astragalo-calcaneal,  and  external  or  superior  calcaneo-navicular.  It  is  to 
be  noted  that  the  synovial  membrane  of  this  joint  is  continuous  with  that 
of  the  astragalo  -  navicular  articulation.  The  bony  articular  surfaces 
of  the  astragalo-calcaneal  joints  cannot  be  studied  until  the  astragalus  is 
removed,  which  should  presently  be  done.  Meanwhile,  by  removing  all  the 
Ugaments,  except  the  interosseous,  and  dividiirg  the  synovial  membranes,  the 
movements  between  the  astragalus  and  os  calcis  are  to  be  studied. 

The  astragalo-navicular  joint  should  now  be  examined.  Inasmuch  as  this 
is  one  of  the  most  important  joints  of  the  foot,  it  should  receive  careful  study. 
The  Ugaments  to  be  dissected  are  as  follows  :  astragalo-navicular,  dorsally 
placed  ;  external  or  superior  calcaneo  -  navicular  ;  and  internal  or  inferior 
calcaneo-navicular,  a  most  important  ligament,  commonly  spoken  of  as  the 
spring  ligament.  The  last-named  ligament  is  to  be  studied  from  two  points 
of  view,  namely,  from  below,  by  removing  the  tendon  of  the  tibialis  posticus, 
and  from  above,  by  removing  the  astragalus.  In  performing  the  latter  dissec- 
tion the  interosseous  astragalo-calcaneal  ligament  is  to  be  studied,  and  it  is 
to  be  obser\'ed  that,  whilst  it  is  the  anterior  ligament  of  the  posterior 
astragalo-calcaneal  joint,  it  is  the  posterior  ligament  of  the  anterior  astragalo- 
calcaneal  joint.  An  excellent  view  is  obtained  from  above  of  how  the  spring 
ligament  supports  and  forms  a  part  of  the  socket  for  the  under  aspect  of  the 
head  of  the  astragalus,  and  from  below  it  can  be  well  seen  how  the  tendon  of 
the  tibialis  posticus  serves  as  an  important  strengthening  adjunct  to  the 
ligament.  It  is  to  be  noted  that  the  synovial  membrane  of  the  astragalo- 
navicular  joint  is  continuous  behind  with  that  of  the  anterior  astragalo- 
calcaneal.  The  movements  at  the  astragalo-navicular  articulation  are  to  be 
carefully  studied,  and  the  manner  in  which  pes  planus  may  be  brought  about 
is  to  be  observed.  Attention  should  also  be  directed  to  the  support  wliich 
the  spring  ligament,  aided  by  the  tendon  of  the  tibialis  posticus,  gives  to  the 
inner  longitudinal  arch  of  the  foot.  The  bony  articular  surfaces  are  also 
to  receive  attention. 

The  calcaneo-cuboid  joint  is  next  to  be  studied.  The  ligaments  to  be  dis- 
sected are  dorsal,  internal  or  interosseous,  long  plantar,  and  short  plantar. 
On  opening  the  joint  the  synovial  membrane  will  be  found  to  be  peculiar  to 
it,  and  the  movements  of  which  the  articulation  is  capable  are  to  be  studied. 
Attention  is  also  to  be  given  to  the  bony  articular  surfaces.  The  naviculo- 
cuboid  joint  is  next  to  be  attended  to,  the  ligaments  being  dorsal,  plantar, 
and  interosseous.  The  remaining  tarsal  articulations  are  to  be  studied  in 
the  following  order  :  naviculo-cuneiform,  intercuneiform,  and  cubo-cuneiform, 
and  the  complicated  synovial  membrane  of  these  articulations  should  be 
examined.     The  bony  articular  surfaces  and  movements  are  also  to  be  studied. 

The  dissector  should  next  direct  his  attention  to  the  tarso-metatarsal 
articulations,  which  should  be  studied  in  the  following  order:  (i)  internal 
tarso-metatarsal,  (2)  middle  tarso-metatarsal,  and  (3)  external  tarso-meta- 
tarsal. Special  notice  should  Ije  taken  of  the  internal  interosseous  ligament 
of  the  middle  tarso-metatarsal  joint.  It  will  be  found  extending  between 
the  outer  surface  of  the  internal  cuneiform  and  the  inner  surface  of  the  base 
of  the  second  metatarsal  bone.  The  synovial  membranes,  bony  articular 
surfaces,  and  movements  of  these  articulations  are  to  be  attended  to,  and 
their  surgery  is  to  be  carefully  studied  in  connection  with  Lisfranc's  operation. 

The  intermetatarsal  articulations  are  to  be  studied  next,  attention  being 
directed  to  the  basal  intermetatarsal  joints,  and  the  union  between  the 
heads  of  the  metatarsal  bones.  The  tarsal  and  tarso-metatarsal  synovial 
membranes  should  be  reviewed  at  this  stage.  The  metatarso-phalangeal 
articulations  are  now  to  be  dissected,  the  ligaments  being  two  lateral  and  an 
inferior  or  plantar  fibrous  jjlate.  The  synovial  membranes,  bony  articular 
surfaces,  and  movements  are  to  be  studied.  Lastly,  the  interphalangeal 
articulations  are  to  be  dissected  in  a  similar  manner  and  to  a  like  extent. 


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QIVI  34  B85  1914-  C.I  v.  1 

Manual  m'  d-dtui-,  '.ys'f-""M'  i  .icd  nr.-ictic 


2002190125 


Buchanan 

T.j[Hmifl1    of    ftrifttnTny-T 


B85 
1914 
v.l 


9mM 


/I. 


